If you've ever washed uncooked rice, you've seen the pale, milky-white water that rinses away. Billions of people across the world eat rice every day. So should everybody who cooks rice wash it beforehand?

This question has been the subject of a number of scientific studies, which have looked at how washing rice affects its texture, nutrition and how well it removes unwanted substances, such as dust, arsenic and microplastics.

Rice is traditionally grown in shallowly flooded fields, as it requires constant irrigation to grow. When the grains are ready, they are harvested and milled to remove the inedible hulls, yielding brown rice, which can be further milled to remove the bran layer, producing white rice.

The act of milling can damage rice kernels, leaving a layer of starch (the substance that makes up much of rice, potatoes and wheat) on the outside. When rice is rinsed, some of this starch is washed away.

In a 2017 study, scientists had speculated that washing rice might change the texture of cooked rice by rinsing off starch that would make grains stick together.

However, subsequent research found that "washing rice makes no difference to the stickiness of the cooked rice," Evangeline Mantzioris, an accredited practicing dietitian at Adelaide University in Australia, told Live Science.

Specifically, a 2019 study showed that "the stickiness of rice is not from the surface starch, amylose, but from another starch within the grain called amylopectin," Mantzioris said. "This is what leaches out during cooking and impacts the stickiness."

The 2019 study found the amount of amylopectin that leaches out of rice during cooking does not depend on whether it is washed. "It is the variety of rice that is important," Mantzioris said. In tests with 10-gram (0.4 ounces) samples of three kinds of rice that were all washed the same amount of time with increasing amounts of water and cooked for 30 minutes, the scientists found that "if you want sticky rice for your dish, you are best using glutinous rice. Medium-grain and jasmine rice are less sticky."

Traditionally, rice was washed for health and safety reasons, "to rinse off dust, insects, little stones and small parts of the husk," Mantzioris said.

However, nowadays, "rice sold in supermarkets and reputable retailers is generally produced under strict quality standards," Bo Wang, a food scientist at Adelaide University, told Live Science. "It is typically cleaned [with machines, such as sifters and blowers], dried, dehusked, milled, graded and packaged before reaching consumers. The drying step particularly reduces moisture content, helping maintain quality and limiting microbial growth during storage. As a result, rice is already a relatively safe product, and washing is generally not required to make it safe for consumption."

Still, "one additional consideration is that some rice may contain naturally occurring inorganic arsenic absorbed from soil and water," Permal Deo, a food scientist with a background in molecular biology at Adelaide University, told Live Science. "Rinsing may help remove some arsenic on the grain surface."

Rinsing rice can also rinse off microplastics, Mantzioris said. A 2021 study found that washing rice before cooking it reduced the amount of plastic contaminating it by 20 to 40%. (It remains uncertain what effect microplastics have on our health, although evidence is growing that microplastics could be harmful.)

Mantzioris noted that washing rice does reduce levels of some important nutrients that naturally dissolve in water, such as copper, iron, zinc and vanadium. However, rice at best offers only a small percentage of one's daily intake of these nutrients. Washing rice, therefore, "is unlikely to affect you nutritionally," she said.

"Long story short, for most consumers, a gentle rinse once or twice before cooking is usually sufficient," Wang said.

This article is for informational purposes only and is not meant to offer medical advice.

Do you know where pumpkins and blueberries come from? Find out with our fruits and vegetables quiz!

Scientists have identified more than 3,000 species of bacteria living in the human gut. We know they play a role in digestion and immune function. But can they also influence the kinds of food we crave?

In a 2014 study in the journal BioEssays, researchers proposed that gut microbes might manipulate the eating behavior of their hosts by generating cravings for foods the bacteria thrive on, or even causing discomfort until the host eats what benefits them.

"We don't always see eye to eye with our microbes," Dr. Joe Alcock, co-author of the study and a professor in the Department of Emergency Medicine at the University of New Mexico, told Live Science.

Salmonella Typhimurium is one example. It hijacks the chemical signals between the gut and brain to keep its host eating through infection.

"Typically, when you have a GI [gastrointestinal] infection, you stop eating," Alcock said. "And Salmonella [Typhimurium] seems to actually impair that … so that animals continue to eat and continue to produce infectious particles in their poop that go on to infect other animals."

However, this was a theoretical paper — it proposed mechanisms by which microbes could manipulate cravings, but hadn't demonstrated that they do. The pathways it proposed — including things like altering taste receptors and hijacking the vagus nerve — were plausible, but unconfirmed, especially in the context of everyday food cravings.

How the microbiome may influence food choices

In 2022, researchers tested this hypothesis. In their study, Kevin Kohl, an associate professor of biology who focuses on how interactions with microbes impact the physiology, ecology and evolution of animal hosts at the University of Pittsburgh, and Brian Trevelline, a microbiologist and postdoctoral fellow at Cornell University, transplanted microbiomes from wild rodents with different diets — carnivore, herbivore and omnivore — into germ-free mice, and then measured what they ate.

"I perhaps naively thought that the carnivore-inoculated mice were going to eat the high-protein diet," Kohl told Live Science. "That's not what we saw."

Instead, the mice with herbivore microbiomes preferred protein, while the mice with carnivore microbiomes preferred carbs. But a key finding held: Different microbiomes led to significantly different food choices.

But how? Gut bacteria can produce many of the same neurotransmitters the brain uses to regulate appetite, including serotonin, which signals to the brain when you've had enough to eat. In fact, roughly 90% of the body's serotonin is produced in the gut, not in the brain, and research has shown that gut bacteria play a direct role in that production.

In the mouse study, the team found that the mice that received the herbivore microbiome had significantly more tryptophan — a building block of serotonin — in their blood. Previous research has shown that higher serotonin levels suppress carbohydrate cravings in particular, which may explain why those mice shifted toward a high-protein diet.

"That might be at least one potential avenue in which the microbiome is affecting diet, appetite and dietary preferences," Trevelline said.

The findings also raise the possibility that the relationship runs both ways. If your microbiome shapes your cravings, and your diet shapes your microbiome, small changes in what you eat could shift the cycle over time.

"I could totally see some feedback cycles where shifts in the microbiome either perpetuate behaviors or bring about different cravings," Kohl said.

However, Kohl and Trevelline's study was in mice. "Food choice is really tricky and totally different in humans," Kohl said. "It's influenced by culture, society, economics, learned behaviors, associations." In other words, a lot of other factors affect our dietary choices.

Still, one recent research paper has started to connect these findings to human health. In a 2025 study published in the journal Nature Microbiology, researchers found that a gut bacterium called Bacteroides vulgatus can suppress sugar cravings in mice by producing a metabolite that triggers the production of glucagon-like peptide-1 (GLP-1), the same hormone targeted by drugs like Ozempic. People with type 2 diabetes also had lower levels of this bacterium, the researchers found.

But Kohl cautioned against giving your microbes too much credit for your choices. "Free will still exists," he said. "The microbes are not driving our choices. But these cravings, low-grade feelings about food — those come from our internal nutritional state" — things like amino acids and other compounds circulating in the body — "which we know is influenced by the microbiome."

People with stronger muscles are more likely to harbor a particular species of bacteria in their guts, and when this bacterial species was fed to mice, they became stronger, a new study finds.

The study authors say the microbe has the potential to be part of a probiotic supplement, potentially boosting muscle strength. However, this would require the researchers to find a way to preserve it in a pill. What’s more, this microbe could serve as a drug to treat frailty in the elderly, assuming future clinical trials in humans reveal the microbe safely improves muscle strength, said study lead author Borja Martinez-Tellez, a sports scientist at Leiden University in the Netherlands.

Gut microbes are intimately linked to many aspects of overall health, and a greater diversity of gut residents has been linked to higher muscle mass and strength in previous studies. In addition, "there is pre-clinical evidence to suggest a link between specific gut bacteria and muscle frailty," Matt Cooke, a nutrition researcher at La Trobe University in Australia who was not involved with the work, told Live Science via email. However, it was unclear which species affect musculature.

In the new study, which was published March 10 in the journal Gut, researchers searched for gut bacteria correlated with muscle strength. They took fecal samples from 90 young participants, ages 18 to 25, and 33 older participants, ages 65 to 71, and asked them to perform strength-training exercises.

Both groups were told to squeeze a handheld device to test their handgrip strength. The researchers found that the participants from both age groups with firmer grips tended to have higher counts of the bacterium Roseburia inulinivorans in their feces. This species helps to digest fibers and typically colonizes the guts of people who consume a Mediterranean diet, which typically includes lots of fruits, vegetables, omega-3-rich fish and extra virgin olive oil.

The young participants were also asked to perform leg-press and bench-press exercises. Those who could lift heavier loads for 10 reps without failing had a greater abundance of gut-dwelling R inulinivorans in addition to another related bacterial species called Roseburia intestinalis, compared with the young participants who had lower strength scores.

However, the link between higher amounts of these microbes and higher load-bearing ability could be explained by other factors. For example, people who strength-train might have an overall healthier lifestyle that involves eating foods that influence their gut microbiome, thereby acquiring more of these bacteria. To determine if R. inulinivorans could actually improve muscle strength, the researchers used a feeding tube to administer various Roseburia species to mice.

Grip strength in mice was assessed using a miniature pull-up bar. Those given R. inulinivorans for four to eight weeks had 30% higher grip strength than other mice. Although this bacterial species enhanced strength, it didn't correlate with muscle growth. Mice given another related species called Roseburia faecis, on the other hand, developed more muscle muscle mass.

Next, the team aimed to figure out how these bacteria were linked to mightier mice. They found that R. inulinivorans caused muscle architecture to change: Muscles that were previously richer in type-I ("slow-twitch") fibers, which contribute to endurance exercises like scurrying in mice or long-distance running in humans, had remolded into type-II ("fast-twitch") fibers, which are pivotal to strength.

"We are able to demonstrate for the first time that there is a direct link between one bacterium and muscle strength," Martinez-Tellez said.

Although these findings are promising, Cooke noted that the mice's gut microbiomes were cleared out with antibiotics before they were given the Roseburia species, so it's not clear whether this depletion affected muscle strength.

The study researchers have filed a patent for using R. inulinivorans to boost muscle strength. They are hoping to develop a probiotic that could boost performance in the gym or, if encouraging clinical trial data on its safety and efficacy emerges, use it as a drug to prevent the onset of frailty in elderly people, Martinez-Tellez told Live Science. "This is not going to be a substitute for exercise training," he said. "It's more of a complement." More research is needed to confirm that such pill-form bacteria could remain in the human gut for long enough to sustain muscular improvements.

It will still be many years before this bacterium could be used by the public. "The problem that we have with this bacterium is that it is strictly anaerobic, which means that if they are exposed for five seconds to oxygen, they die," Martinez-Tellez said. He and his colleagues will need to develop an air-tight pill that preserves the shelf life of this species.

"More research is needed in humans to confirm these animal findings," Cooke said, adding that further studies should involve supplementing people with these bacteria and observing the effects on their muscles and how safe they are to take.

Down the line, Martinez-Tellez wants to explore whether other gut residents could have a similar effect on physical performance, broadening the possibilities of boosting brawn through the gut.

This article is for informational purposes only and is not meant to offer medical advice.

The patient: A 34-year-old man in Mexico

The symptoms: Within seconds of drinking a "smoky" alcoholic beverage at a bar, the man felt an intense pain in his stomach.

What happened next: The man was admitted to an emergency department. In addition to experiencing abdominal pain, he was sweating profusely and had become lethargic. His vital signs were a cause for concern. He had an abnormally fast heartbeat of 124 beats per minute, compared with a typical resting heart rate of 60 to 100 bpm. He was also breathing faster than normal and had low blood pressure, and his body temperature had dropped to 95.7 degrees Fahrenheit (35.4 degrees Celsius).

The patient reported feeling discomfort and tenderness when the doctors touched his abdomen in four places. This revealed that the pain was widespread rather than localized to one organ as is often the case with conditions like appendicitis.

The man told his doctors that the drink he'd consumed had been infused with liquid nitrogen, and the doctors suspected that the substance ruptured the man's stomach. When liquid nitrogen warms and converts to a gas, it expands in volume by roughly 700 times. Owing to the enormous difference in temperature between the liquid, at minus 351 F (minus 196 C), and the man's body, the substance could have rapidly swelled into a gas, the doctors wrote in a report of the man's case, and thus popped the stomach like an overinflated balloon.

To assess if there was a perforation in the man's stomach, the doctors listened for signs of air while tapping on his abdomen. Some areas of the abdomen, such as the stomach, normally contain air and produce a high-pitched, "tympanic" sound when tapped. By contrast, more solid or liquid-containing organs, like the liver sitting on top of the stomach, produce a low-pitched, "dull" sound. In this patient, however, the entire abdomen was tympanic, including the region above the stomach.

The diagnosis: Next, the doctors observed the patient's soft tissue using CT scans. From those scans, they discovered a layer of trapped nitrogen gas in the patient's abdomen, just above his stomach and below his lungs — a condition known as pneumoperitoneum. This confirmed that the gas had ruptured the man's stomach and collected above it.

The treatment: The doctors made a small, keyhole incision in the patient's abdomen that released the trapped nitrogen gas. They then inserted a laparoscope — a thin tube with a camera — through the key-hole and into the stomach to find and repair the perforation. Finally, they sutured and sealed the 1.2-inch-wide (3 centimeters) hole, using a piece of fatty tissue from elsewhere in the man's abdomen.

The patient made a quick recovery and was discharged three days later, after he demonstrated he could tolerate a liquid diet, the doctors noted in the report.

What makes the case unique: Besides bursting the stomach, liquid nitrogen that gets consumed before it completely evaporates from food and drink can cause permanent cold burns in the body, as the substance freezes water within human cells and damages tissue.

Luckily, the patient did not experience any cold burns in his mouth, esophagus or stomach. The doctors believed this was thanks to the "Leidenfrost effect," a physical phenomenon that describes how a liquid behaves when it meets a surface substantially warmer than its boiling point. The outermost layer of the liquid instantly vaporizes, temporarily shielding the warm surface (in this case, human tissue) from the remaining cold liquid. This insulating gas layer may explain why the liquid nitrogen didn't burn the man while passing through his gullet.

Liquid nitrogen is often used in food preparation. For instance, flash-freezing meat with this substance preserves its protein structure and locks in moisture more efficiently than other freezing methods do. It can also preserve fats in seafood and help it retain its flavor. However, by the time these food items hit the dinner table, they are safe to consume because the nitrogen has completely bubbled off.

Garnishing food and drink with liquid nitrogen for its smoky, theatrical appearance can be dangerous if impatient gourmands consume those items before the liquid has completely vaporized. As such, it's best to wait until the cloud dissipates. Often liquid nitrogen is used to create a smoke illusion near food, but not within it, minimizing the risk of injury.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical or food safety advice.

The U.S. federal government just released a new version of the food pyramid, along with a recommendation that Americans eat more protein than previously advised.

The previously recommended daily intake of protein was around 0.8 grams for each kilogram of body weight. That recommendation aimed at meeting the nutritional needs of an average, sedentary adult. Now, the new dietary guidelines suggest people should consume between 1.2 and 1.6 grams of protein per kg of body weight per day.

So, to meet the new recommendations, a person weighing 154 pounds (70 kg) would need to consume around 84 to 112 grams (3 to 4 ounces) of protein per day, as opposed to 56 grams (2 ounces) under the old recommendation.

"It is unclear why the [Dietary Guidelines for Americans] increased the recommendation by 50% to 100%," Alice Lichtenstein, an American Heart Association fellow and nutrition science professor at Tufts University, told Live Science in an email.

Notably, scientists previously estimated that the average U.S. adult's protein consumption generally exceeded the old guideline. A 2013 study estimated it at 1.2 to 1.4 grams per kg of body weight per day, while a 2021 dietary data brief noted men and women were consuming 97 grams and 69 grams on a given day, respectively.

Nonetheless, the shift in guidance raises some questions: Are there benefits to upping your protein intake? And is there an upper limit you shouldn't cross?

Experts told Live Science that there's no single, agreed-upon maximum amount of protein you can eat in a day. That said, if you're not particularly active, pushing your protein intake beyond what the old recommendation suggested is unlikely to be very beneficial, they said. Additionally, it would be harmful to boost your protein intake at the expense of eating other macronutrients, like fat and carbs.

Why is protein important?

Proteins are the body's building blocks, forming everything from muscles and hormones to digestive enzymes and the hemoglobin that carries oxygen in the blood.

Protein-rich foods include meat, fish and eggs, as well as tofu, beans and nuts. The proteins in these foods get broken down by our bodies into their component parts — amino acids — which cells can use to produce the proteins we need. While the body can produce some amino acids on its own, there are nine, called essential amino acids, that we can get only through our diet.

A given person's protein requirements vary depending on a number of factors, with one of the more crucial ones being how much they exercise. So generally, increases in protein intake should be accompanied by increases in activity levels, Lichtenstein told Live Science.

"Most of the studies that I am aware of have not demonstrated that increasing protein intake above current recommendations increases lean muscle mass," she said. "If it does, it needs to be coupled with certain types of physical activity, not a strong point for most people." Those types of activity might include strength and endurance training, for instance.

Historically, it's been recommended that people who regularly exercise get about 1.1 to 1.5 grams per kg per day, while people training for athletic events might eat up to 1.7 grams per kg per day.

Notably, active people still need to take in adequate energy from carbs and fats. If they don't, the body may resort to using amino acids as fuel, effectively increasing the amount of protein they need to make up for the loss of protein building blocks in the body.

Another factor that influences our protein requirements is age. As you get older, the body's ability to build new muscle proteins gets disrupted, leading to muscle loss and frailty. Studies suggest that eating more protein — about 1 to 1.2 grams per kg of body weight a day — could help mitigate these effects seen in middle-aged and older people.

Effects of high-protein diets

Research has tied high-protein diets, typically considered around 1.2 to 2 grams per kg of body weight per day, to both positive and negative health outcomes.

In one review of studies on the topic, researchers compared high- and low-protein diets and found that the former was tied to greater weight loss and thus lower BMI. However, another review tied high-protein consumption to a higher risk of bone-density loss and kidney stones.

An overconsumption of protein may increase levels of the amino acid leucine, which can then interfere with how immune cells clear plaque from blood vessels, one study of humans and lab mice found. This could boost the risk of heart attack or stroke. Based on this finding, the study authors suggested that getting more than 22% of your daily calories from protein — around 1.6 grams per kg of body weight — could do more harm than good.

Leucine is found in a variety of animal- and plant-based protein sources. Additionally, protein sources that are high in purine — such as red meat, organs like kidney, and certain types of seafood — can lead to gout and kidney stones if consumed in excess.

"It's important to note that there is no single, official upper limit," Bridget Cassady, a registered dietitian nutritionist (RDN) at Abbott, told Live Science in an email. "An amount that is considered 'excessive' will be different based on your needs varying with age, body weight, activity level, health status."

Broadly speaking, though, Cassady said that healthy individuals can safely consume "moderately high" amounts of protein — around 2 grams per kg per day — as long as it's part of a balanced diet. Protein consumption should not come at the expense of other nutrients; if it starts crowding out fiber-rich plants, healthy fats, or whole-food carbohydrates, that's when protein intake could start becoming a concern, she said.

At the extreme, a super high-protein diet could put strain on the kidneys, which can filter only so much urea — a protein waste product — from the blood at a given time. That's why people with existing kidney problems are advised to avoid high-protein diets, according to Cleveland Clinic. If your urine turns bubbly or foamy, that can mean there's a high level of protein in the urine, which could signal kidney damage.

This article is for informational purposes only and is not meant to offer medical or dietary advice.

The U.S. government has officially resurrected the food pyramid — and flipped it on its head.

The new food chart emphasizes meats, dairy and what it calls "healthy fats," as well as fruits and vegetables. It accompanies new nutrition guidance that upholds some well-established diet recommendations while breaking with others.

The Departments of Agriculture and Health and Human Services released the new dietary guidelines on Wednesday (Jan. 7), and in doing so, they retired MyPlate, a visual guide to healthy eating that replaced the food pyramid in 2011. The so-called New Pyramid is an inverted triangle with protein, dairy and "healthy fats" at the top, alongside vegetables and fruits. At the bottom of the flipped pyramid are whole grains.

The brief guidelines accompanying the New Pyramid place a heavy emphasis on avoiding highly processed foods, refined carbohydrates and added sugars, noting that the unrefined sugars found in foods like fruit and milk are not considered "added."

The guidelines also specify that healthy fats include those found in meats, poultry, eggs, omega-3–rich seafood, nuts, seeds, full-fat dairy, olives and avocados. Olive oil (mostly unsaturated fat) and butter and beef tallow (mostly saturated fat) are listed as good options for cooking oils. That said, the guidelines don't change the long-standing guidance about limiting one's consumption of saturated fats, stating that they should not exceed 10% of a person's total daily calories.

The guidelines significantly increase recommended protein intake, NBC reported. Established guidelines say that 0.8 grams of protein per 2.2 pounds (1 kilogram) of body weight would meet the daily nutrition requirements of the average, sedentary adult. Higher amounts are recommended for physically active adults (about 1.1 to 1.5 grams per kg) and older adults (about 1 to 1.2 grams per kg).

The new guidelines recommend a baseline daily protein intake of 1.2 to 1.6 grams per kilogram of body weight. So for a 150-pound (68 kg) person, that's a jump from 54.4 grams of protein a day to about 81.6 to 108.8 grams.

Health Secretary Robert F. Kennedy Jr. had delayed releasing new dietary guidelines for months after rejecting the work of a 20-person scientific advisory committee assembled under President Joe Biden, STAT reported. The committee was poised to recommend plant-forward diets, rather than meat-centric ones, and had concluded that the existing research on ultraprocessed foods was inadequate to develop clear recommendations.

(The definition of "ultraprocessed" can be difficult to pin down, and while many experts agree ultraprocessed foods are unhealthy to eat in excess, it's hard to know if every food under the ultraprocessed umbrella carries the same health risks.)

The new guidelines, meanwhile, put a notable emphasis on meat and dairy and say to avoid highly processed foods, without clearly defining what "highly processed" means. They do say to avoid packaged, prepared and ready-to-eat meals; foods that are salty or sweet; sugar-sweetened beverages; and foods containing artificial flavors, or preservatives, or low-calorie, non-nutritive sweeteners.

Some experts worry that the guidelines' emphasis on meat and dairy — including the notable inclusion of steak, ground beef and a carton of full-fat milk on the illustration of the inverted pyramid — may promote high intakes of red meat and dairy products. This "will not lead to optimally healthy diets or a healthy planet," Dr. Walter Willett, a professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health, told CNN in an email.

"These guidelines recommend heavily meat-based diets — protein is a euphemism for meat," Marion Nestle, a nutritionist and professor emeritus at New York University, told STAT via email.

MyPlate previously sorted foods into five categories — fruits, vegetables, grains, protein, and dairy and fortified soy alternatives — and provided general recommendations for how much food a person should eat from each category based on their age and sex. As a rule of thumb, fruit and vegetables made up half the plate, and proteins and grains comprised the other half, with a small amount of dairy featured on the side. Healthy oils were defined as vegetable oils and those found in seafood and nuts.

MyPlate also emphasized that additional factors beyond age and sex — such as height, weight, physical activity levels, and whether you are pregnant or breastfeeding — may affect daily nutrition needs. About 150 pages of guidelines detailed those nuances, and also set specific intake limits on added sugars, saturated fats, sodium and alcohol.

The new guidelines also acknowledge that a person's nutrition needs may vary depending on various factors, and they provide some brief guidance for specific populations, such as infants, pregnant and lactating women, and older adults.

They don't note a specific limit for daily alcohol intake, instead saying that people should generally "consume less" for better overall health. They also specified groups, such as pregnant women, who should avoid it altogether.

They added that those with a "family history of alcoholism [should be] be mindful of alcohol consumption and associated addictive behaviors." (While genetics do play a role in who is vulnerable to alcohol use disorder, genes are not the only factor at play, and people without a family history can also develop the addiction.)

These national dietary guidelines influence what's included in school lunches and military meals, as well as federal food assistance programs such as the Supplemental Nutrition Assistance Program (SNAP), NBC reported. A White House spokesperson said the new guidance will be phased into schools and federal food programs over the next two years.

This article is for informational purposes only and is not meant to offer medical or dietary advice.

The patient: A man in his 50s in Nottingham, England

The symptoms: The man suddenly developed numbness on his left side, as well as unsteadiness.

What happened next: Upon the man's admission to a hospital, his blood pressure was found to be 254/150 millimeters of mercury (mm Hg), according to a report of the case. That extremely high reading indicates a hypertensive crisis. A neurological exam confirmed that he had numbness across the entire left side of his body and that he had trouble coordinating movements with his left arm and leg.

A CT angiogram — a scan that details the blood vessels, including blockages and damage — showed signs that the man may have experienced a sudden spasming and narrowing of the cerebral arteries, an event known as reversible cerebral vasoconstriction syndrome (RCVS). Additionally, an MRI showed tissue death in the thalamus, which acts as a relay station for motor and sensory information; specifically, he had damage in the thalamus located on the right side of the brain.

There were no other notable findings on the patient's exam, and his medical history lacked any history of smoking, alcohol use or substance abuse. The report describes him as "normally fit and well."

The diagnosis: The man was diagnosed with a right thalamic lacunar stroke. A lacunar stroke happens when a blood vessel that carries blood to one of the brain's deep structures gets blocked. Right-sided strokes affect the sensation and movement on the left side of the body, and vice versa.

The treatment: The man was treated with a combination of physiotherapy and occupational therapy while at the hospital, and he began taking blood thinners to help prevent another stroke. He also began taking a cholesterol-lowering drug and blood-pressure-lowering medications.

The man had several follow-up appointments over the next three months. "He appeared to have made an excellent functional recovery, although the sensory symptoms [of numbness] were persistent and deteriorated throughout the day," his doctors noted. His blood pressure had also remained persistently high, so he began taking additional blood-pressure drugs.

At that point, the doctors asked the patient more questions about his lifestyle and learned that he consumed an average of eight cans of a "high-potency" energy drink each day. Each can contained 160 milligrams of caffeine per 16 fluid ounces, adding up to about 1.2 grams of caffeine a day. (Less than 400 milligrams is considered a safe daily dose of caffeine.)

The patient was advised to stop consuming energy drinks, and his blood pressure quickly fell to normal levels. He was able to stop taking all of his prescribed medications within three weeks of quitting the drinks.

"Further follow-up at 3 and 6 months showed complete resolution of hypertension and a complete recovery from the stroke with full return to work," his doctors reported. Eight years later, he had had no further strokes, though he still had lingering sensory issues on his left side from the first stroke.

What makes the case unique: Although he was otherwise healthy, the man's excessive consumption of energy drinks appeared to have driven his high blood pressure and subsequent stroke.

The case report authors noted that the high caffeine levels were likely a big culprit, but they hypothesized that other common ingredients in energy drinks may have contributed to the stroke risk. For instance, when combined with caffeine, taurine and guarana may amplify the stimulant's blood-pressure-boosting effects and its effects on blood-vessel constriction, they theorized. Taurine, an amino acid, is often added to energy drinks for its purported ability to increase exercise capacity, while guarana is a plant that is similarly perceived to have health benefits and whose seeds contain caffeine.

Additionally, the high sugar content of many energy drinks may further raise the risk by causing inflammation and dysfunction in the lining of blood vessels.

The authors cited a handful of published medical case reports in which the excessive consumption of energy drinks or of individual energy drink ingredients was tied to cardiovascular issues, including dangerously high blood pressure.

They concluded that "both acute and chronic intake" of energy drinks may increase the risk of cardiovascular disease and stroke.

"Healthcare professionals should consider specific questioning related to ED [energy drink] consumption in young patients presenting with stroke or unexplained hypertension," they concluded. Importantly, the risk seems to be reversible, they added, given that quitting energy drinks appears to resolve the related problems.

For the patient's part, he said, "I obviously wasn't aware of the dangers drinking energy drinks were causing to myself. [I] have been left with numbness [in my] left hand side hand and fingers, foot and toes even after 8 years."

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

The patient: A 64-year-old woman in Canada

The symptoms: Paramedics brought the patient to the emergency department after she developed sudden weakness, nausea, vomiting, diarrhea and lower abdominal pain.

What happened next: The woman told doctors she'd developed the symptoms minutes after consuming two cups of homemade juice made from pureed calabash (Lagenaria siceraria), also known as bottle gourd. She said she'd made and drunk juice from store-bought calabash every day for years, according to a report of the case. However, on this occasion, she noted that it tasted "abnormally bitter," rather than having its more typical mild squash flavor.

Tests revealed that the woman's heart rate and breathing rate were high, and her blood pressure was initially high and then fell concerningly low. Her extremities were also unusually cool to the touch, indicating she had poor circulation. Meanwhile, one of the chambers of her heart was pumping very forcefully, and an echocardiogram suggested she was having other heart issues.

The medical team restored the woman's blood pressure to normal levels by giving her intravenous fluids, but she still subsequently had several episodes of "profound" low pressure. She also continued to experience diarrhea and vomited blood several times.

She was then transferred to the intensive care unit (ICU), where doctors examined her gastrointestinal tract via gastroscopy, in which a thin tube with a camera in it is inserted into the mouth and guided into the throat and stomach. They found that her stomach lining was inflamed and bleeding as a result of tissue damage, which was likely caused by poor oxygen delivery to the tissue.

The diagnosis: The patient was diagnosed with shock, a life-threatening condition in which blood flow starkly declines and ultimately injures organs. In this case, the shock stemmed from toxins in the squash juice. This "bitter bottle gourd poisoning" is a type of "toxic squash syndrome," which is caused by eating toxic substances sometimes found in squashes and gourds.

Calabash is specifically a "cucurbit," meaning it belongs to the Cucurbitaceae family that includes cucumbers, pumpkins, watermelon and zucchini. Cucurbits produce bitter-tasting chemicals called cucurbitacins, which can have toxic effects if consumed in large enough quantities. Domesticated varieties of these plants have been bred to contain minimal quantities of cucurbitacins so that they're both palatable and safe for humans to eat. But in some cases, cucurbits may accumulate these chemicals as they ripen, posing a rare risk to people who consume them.

"If ingested, cucurbitacin is toxic to humans by various purported albeit uncertain mechanisms," the report authors noted. The toxin is thought to disrupt signaling in cells and make blood vessels more permeable, and it ultimately injures mucous membranes in the body, especially in the digestive tract.

"It is suspected that the gourd’s degree of bitterness correlates with its cucurbitacin concentration and thus toxicity; however, this is not definitively supported in the literature," the authors added.

The treatment: There is no specific antidote to bitter-gourd poisoning, so the medical team continued to monitor the patient's vital signs and stabilize them as needed. Her shock and associated symptoms went away after she'd spent five days in the ICU.

The patient was then discharged, and on a follow-up call, she reported sudden and progressive hair loss that set in about two weeks after she'd been admitted to the hospital. The doctors noted that this is another likely symptom of "bitter bottle gourd poisoning and further supported this diagnosis." Hair loss has been reported in other cases of the syndrome.

What makes the case unique: Toxic squash syndrome is considered very rare, and this was the first such case ever reported in Canada. Similar cases had previously been reported in other countries, such as India, where calabash juice is used in some forms of traditional medicine.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

When you open the refrigerator and find a wedge of cheese flecked with green mold, or a package of chicken that smells faintly sour, it can be tempting to gamble with your stomach rather than waste food.

But the line between harmless fermentation and dangerous spoilage is sharp. Consuming spoiled foods exposes the body to a range of microbial toxins and biochemical by-products, many of which can interfere with essential biological processes. The health effects can vary from mild gastrointestinal discomfort to severe conditions such as liver cancer.

I am a toxicologist and researcher specializing in how foreign chemicals such as those released during food spoilage affect the body. Many spoiled foods contain specific microorganisms that produce toxins. Because individual sensitivity to these chemicals varies, and the amount present in spoiled foods can also vary widely, there are no absolute guidelines on what is safe to eat. However, it's always a good idea to know your enemies so you can take steps to avoid them.

Nuts and grains

In plant-based foods such as grains and nuts, fungi are the main culprits behind spoilage, forming fuzzy patches of mold in shades of green, yellow, black or white that usually give off a musty smell. Colorful though they may be, many of these molds produce toxic chemicals called mycotoxins.

Two common fungi found on grains and nuts such as corn, sorghum, rice and peanuts are Aspergillus flavus and A. parasiticus. They can produce mycotoxins known as aflatoxins, which form molecules called epoxides that can trigger mutations when they bind to DNA. Repeated exposure to aflatoxins can damage the liver and has been linked to liver cancer, especially for people who already have other risk factors for it, such as hepatitis B infection.

Fusarium is another group of fungal pathogens that can grow as mold on grains such as wheat, barley and corn, especially at high humidity. Infected grains may appear discolored or have a pinkish or reddish hue, and they might emit a musty odor. Fusarium fungi produce mycotoxins called trichothecenes, which can damage cells and irritate the digestive tract. They also make another toxin, fumonisin B1, which disrupts how cells build and maintain their outer membranes. Over time, these effects can harm the liver and kidneys.

If grains or nuts look moldy, discolored or shriveled, or if they have an unusual smell, it's best to err on the side of caution and throw them out. Aflotoxins, especially, are known to be potent cancer-causing agents, so they have no safe level of exposure.

Fruits

Fruits can also harbor mycotoxins. When they become bruised or overripe, or are stored in damp conditions, mold can easily take hold and begin producing these harmful substances.

One biggie is a blue mold called Penicillium expansum, which is best known for infecting apples but also attacks pears, cherries, peaches and other fruit. This fungus produces patulin, a toxin that interferes with key enzymes in cells to hobble normal cell functions and generate unstable molecules called reactive oxygen species that can harm DNA, proteins and fats. In large amounts, patulin can injure major organs such as the kidneys, liver, digestive tract and immune system.

P. expansum's blue and green cousins, Penicillium italicum and Penicillium digitatum, are frequent flyers on oranges, lemons and other citrus fruits. It's not clear whether they produce dangerous toxins, but they taste awful.

It is tempting to just cut off the moldy parts of a fruit and eat the rest. However, molds can send out microscopic, rootlike structures called hyphae that penetrate deeply into food, potentially releasing toxins even in seemingly unaffected bits. Especially for soft fruits, where hyphae can grow more easily, it's safest to toss moldy specimens. Do it at your own risk, but for hard fruits I do sometimes just cut off the moldy bits.

Cheese

Cheese showcases the benefits of controlled microbial growth. In fact, mold is a crucial component in many of the cheeses you know and love. Blue cheeses such as Roquefort and Stilton get their distinctive, tangy flavor from chemicals produced by a fungus called Penicillium roqueforti. And the soft, white rind on cheeses such as Brie or Camembert contributes to their flavor and texture.

On the other hand, unwanted molds look fuzzy or powdery and may take on unusual colors. Greenish-black or reddish molds, sometimes caused by Aspergillus species, can be toxic and should be discarded. Also, species such as Penicillium commune produce cyclopiazonic acid, a mycotoxin that disrupts calcium flow across cell membranes, potentially impairing muscle and nerve function. At high enough levels, it may cause tremors or other nervous system symptoms. Fortunately, such cases are rare, and spoiled dairy products usually give themselves away by their sharp, sour, rank odor.

As a general rule, discard soft cheeses such as ricotta, cream cheese and cottage cheese at the first sign of mold. Because these cheeses contain more moisture, the mold's filaments can spread easily.

Hard cheeses, including cheddar, Parmesan and Swiss, are less porous. So cutting away at least one inch around the moldy spot is more of a safe bet — just take care not to touch the mold with your knife.

Meat

While molds are the primary concern for plant and dairy spoilage, bacteria are the main agents of meat decomposition. Telltale signs of meat spoilage include a slimy texture, discoloration that's often greenish or brownish and a sour or putrid odor.

Some harmful bacteria do not produce noticeable changes in smell, appearance or texture, making it difficult to assess the safety of meat based on sensory cues alone. That stink, though, is caused by chemicals such as cadaverine and putrescine that are formed as meat decomposes, and they can cause nausea, vomiting and abdominal cramps, as well as headaches, flushing or drops in blood pressure.

Spoiled meats are rife with bacterial dangers. Escherichia coli, a common contaminant of beef, produces shiga toxin, which chokes off some cells' ability to make proteins and can cause a dangerous kidney disease called hemolytic uremic syndrome. Poultry often carries the bacterium Campylobacter jejuni, which produces a toxin that invades gastrointestinal cells, often leading to diarrhea, abdominal cramps and fever. It can also provoke the body's immune system to attack its own nerves, potentially sparking a rare condition called Guillain-Barré syndrome, which can lead to temporary paralysis.

Salmonella, found in eggs and undercooked chicken, is one of the most common types of food poisoning, causing diarrhea, nausea and abdominal cramps. It releases toxins into the lining of the small and large intestines that drive extensive inflammation. Clostridium perfringens also attacks the gut, but its toxins work by damaging cell membranes. And Clostridium botulinum, which can lurk in improperly stored or canned meats, produces botulinum toxin, one of the most potent biological poisons — lethal even in tiny amounts.

It is impossible for meat to be totally free of bacteria, but the longer it sits in your refrigerator — or worse, on your counter or in your grocery bag — the more those bacteria multiply. And you can't cook the yuck away. Most bacteria die at meat-safe temperatures — between 145 and 165 degrees Fahrenheit (63-74 C) — but many bacterial toxins are heat stable and survive cooking.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Frozen shrimp imported to the U.S. from an Indonesia-based company may have been exposed to a radioactive substance, the U.S. Food and Drug Administration (FDA) warned this week.

And while the recall initially only affected products sold by Walmart, the agency has widened its recall to include products sold by another distributor.

The products were processed by PT. Bahari Makmur Sejati, also referred to as BMS Foods. The FDA launched an investigation after U.S. Customs officials detected cesium-137 (Cs-137) — a radioactive form of cesium — in shipping containers carrying the shrimp that were delivered to Los Angeles; Houston; Savannah, Georgia; and Miami.

Analyses of the containers' contents confirmed the presence of Cs-137 in one sample of breaded shrimp. The containers that tested positive were not allowed to enter the U.S., and no products that tested positive have entered the food supply.

However, as a precaution, the FDA has looked into other shrimp products that were imported from the same company but prior to the detection of Cs-137. Despite those previously imported products not testing positive for radioactive material at the time, the FDA has recommended people not consume them and that retailers recall them.

"To date, FDA has learned that Walmart has received implicated raw frozen shrimp, imported after the date of first detection of Cs-137 by CBP [Customs & Border Patrol], but from shipments that did not alert for Cs-137," the statement says. BMS Foods has clearly handled products under conditions that would open the door to Cs-137 contamination, the agency explained, so there's a possibility these other products could pose a safety concern, as well.

As such, the FDA recommended that Walmart recall the affected products, and it lists the specific lot numbers affected in its warning. Anyone who has recently bought frozen shrimp from Walmart that matches the descriptions released by the FDA should throw it away and not eat or serve it.

On Thursday (Aug. 19), the FDA announced that more frozen shrimp are potentially affected by the issue. They've issued a recall of bagged, frozen shrimp distributed by Southwind Foods, LLC of Carson, California between July 17 and Aug. 8. The recalled products were distributed or sold in Alabama, Arizona, California, Massachusetts, Minnesota, Pennsylvania, Utah, Virginia, and Washington.

Related: How radioactive is the human body?

According to the FDA, the nonradioactive form of cesium, called stable cesium, naturally occurs in the environment and is found in rocks, soil and dust. The element can also travel long distances through the air, before settling on the ground or in water. Cesium can become radioactive when it's exposed to decaying uranium, nuclear explosions or nuclear reactor accidents. Cesium-137 has a half-life of about 30 years, meaning it takes three decades for the isotope's radioactivity to decrease by half.

"Because it is widespread worldwide, trace amounts of Cs-137 can be found in the environment, including soil, food, and air," the FDA statement noted. The agency evaluates any detection of the isotope in food products to determine if follow-up action is warranted.

The FDA found Cs-137 in only one of the BMS shrimp products tested, but that does not necessarily mean other products aren't also contaminated, the agency noted. The amount of the isotope found in the breaded shrimp sample was not high enough to cause immediate harm to a consumer in the short term, the tests suggested.

However, the level detected could pose a risk if someone were to consume the product repeatedly over a longer period of time, especially when you combine that exposure with the baseline, low-level radiation that we're exposed to in the environment and through routine medical procedures, such as X-rays. Over the long term, repeated exposure to Cs-137 could raise the risk of cancer by damaging DNA.

The FDA's investigation into the situation is ongoing, but the agency has already confirmed that products from BMS Foods have violated the Federal Food, Drug, and Cosmetic Act. That's because the products appear to have been "prepared, packed, or held under insanitary conditions whereby it may have become contaminated with Cs-137 and may pose a safety concern," the statement explains.

The company has been added to a new import alert for chemical contamination, which effectively stops any of its shrimp products from entering the U.S. until the company corrects those underlying violations.

At this point, the root cause of the contamination is unknown, but the FDA is "working with Indonesian seafood regulatory authorities to investigate."

"FDA will continue working with industry to trace all implicated products processed by PT. Bahari Makmur Sejati through the supply chain to gather as much information about them as possible and take action as appropriate," FDA officials said in the statement.

Editor's Note: This story was updated on Friday, Aug. 22 at 4:45 p.m. EDT to note that the frozen shrimp recall has now been expanded to include products from an additional distributor.

This article is for informational purposes only and is not meant to offer medical advice.

A man consulted ChatGPT prior to changing his diet. Three months later, after consistently sticking with that dietary change, he ended up in the emergency department with concerning new psychiatric symptoms, including paranoia and hallucinations.

It turned out that the 60-year-old had bromism, a syndrome brought about by chronic overexposure to the chemical compound bromide or its close cousin bromine. In this case, the man had been consuming sodium bromide that he had purchased online.

A report of the man's case was published Tuesday (Aug. 5) in the journal Annals of Internal Medicine Clinical Cases.

Live Science contacted OpenAI, the developer of ChatGPT, about this case. A spokesperson directed the reporter to the company's service terms, which state that its services are not intended for use in the diagnosis or treatment of any health condition, and their terms of use, which state, "You should not rely on Output from our Services as a sole source of truth or factual information, or as a substitute for professional advice." The spokesperson added that OpenAI's safety teams aim to reduce the risk of using the company's services and to train the products to prompt users to seek professional advice.

"A personal experiment"

In the 19th and 20th centuries, bromide was widely used in prescription and over-the-counter (OTC) drugs, including sedatives, anticonvulsants and sleep aids. Over time, though, it became clear that chronic exposure, such as through the abuse of these medicines, caused bromism.

Related: What is brominated vegetable oil, and why did the FDA ban it in food?

This "toxidrome" — a syndrome triggered by an accumulation of toxins — can cause neuropsychiatric symptoms, including psychosis, agitation, mania and delusions, as well as issues with memory, thinking and muscle coordination. Bromide can trigger these symptoms because, with long-term exposure, it builds up in the body and impairs the function of neurons.

In the 1970s and 1980s, U.S. regulators removed several forms of bromide from OTC medicines, including sodium bromide. Bromism rates fell significantly thereafter, and the condition remains relatively rare today. However, occasional cases still occur, with some recent ones being tied to bromide-containing dietary supplements that people purchased online.

Prior to the man's recent case, he'd been reading about the negative health effects of consuming too much table salt, also called sodium chloride. "He was surprised that he could only find literature related to reducing sodium from one's diet," as opposed to reducing chloride, the report noted. "Inspired by his history of studying nutrition in college, he decided to conduct a personal experiment to eliminate chloride from his diet."

(Note that chloride is important for maintaining healthy blood volume and blood pressure, and health issues can emerge if chloride levels in the blood become too low or too high.)

The patient consulted ChatGPT — either ChatGPT 3.5 or 4.0, based on the timeline of the case. The report authors didn't get access to the patient's conversation log, so the exact wording that the large language model (LLM) generated is unknown. But the man reported that ChatGPT said chloride can be swapped for bromide, so he swapped all the sodium chloride in his diet with sodium bromide. The authors noted that this swap likely works in the context of using sodium bromide for cleaning, rather than dietary use.

In an attempt to simulate what might have happened with their patient, the man's doctors tried asking ChatGPT 3.5 what chloride can be replaced with, and they also got a response that included bromide. The LLM did note that "context matters," but it neither provided a specific health warning nor sought more context about why the question was being asked, "as we presume a medical professional would do," the authors wrote.

Recovering from bromism

After three months of consuming sodium bromide instead of table salt, the man reported to the emergency department with concerns that his neighbor was poisoning him. His labs at the time showed a buildup of carbon dioxide in his blood, as well as a rise in alkalinity (the opposite of acidity).

He also appeared to have elevated levels of chloride in his blood but normal sodium levels. Upon further investigation, this turned out to be a case of "pseudohyperchloremia," meaning the lab test for chloride gave a false result because other compounds in the blood — namely, large amounts of bromide — had interfered with the measurement. After consulting the medical literature and Poison Control, the man's doctors determined the most likely diagnosis was bromism.

Related: ChatGPT is truly awful at diagnosing medical conditions

After being admitted for electrolyte monitoring and repletion, the man said he was very thirsty but was paranoid about the water he was offered. After a full day in the hospital, his paranoia intensified and he began experiencing hallucinations. He then tried to escape the hospital, which resulted in an involuntary psychiatric hold, during which he started receiving an antipsychotic.

The man's vitals stabilized after he was given fluids and electrolytes, and as his mental state improved on the antipsychotic, he was able to inform the doctors about his use of ChatGPT. He also noted additional symptoms he'd noticed recently, such as facial acne and small red growths on his skin, which could be a hypersensitivity reaction to the bromide. He also noted insomnia, fatigue, muscle coordination issues and excessive thirst, "further suggesting bromism," his doctors wrote.

He was tapered off the antipsychotic medication over the course of three weeks and then discharged from the hospital. He remained stable at a check-in two weeks later.

"While it is a tool with much potential to provide a bridge between scientists and the nonacademic population, AI also carries the risk for promulgating decontextualized information," the report authors concluded. "It is highly unlikely that a medical expert would have mentioned sodium bromide when faced with a patient looking for a viable substitute for sodium chloride."

They emphasized that, "as the use of AI tools increases, providers will need to consider this when screening for where their patients are consuming health information."

Adding to the concerns raised by the case report, a different group of scientists recently tested six LLMs, including ChatGPT, by having the models interpret clinical notes written by doctors. They found that LLMs are "highly susceptible to adversarial hallucination attacks," meaning they often generate "false clinical details that pose risks when used without safeguards." Applying engineering fixes can reduce the rate of errors but does not eliminate them, the researchers found. This highlights another way in which LLMs could introduce risks into medical decision-making.

This article is for informational purposes only and is not meant to offer medical or dietary advice.

Anecdotal reports suggest that people who are taking weight loss drugs like Ozempic and Wegovy say they suddenly find it easier to turn down an extra drink on a night out. But does research align with these stories? Do these weight loss drugs cause people to reduce their alcohol consumption?

Although more research is needed, evidence is mounting that GLP-1 receptor agonists — a class of drugs that includes semaglutide (brand names Ozempic and Wegovy) and liraglutide (Saxenda) — do seem to reduce alcohol consumption, and researchers are hopeful that these drugs could help curb problematic drinking.

This research is still in its early phases, and scientists still don't understand how these drugs might act on the brain to reduce alcohol consumption. But more than a dozen clinical trials are underway to answer these questions.

"This is a field that's moved really quickly in the last couple of years and will probably move even more quickly in the next two years," said Christian Hendershot, director of clinical research at the University of Southern California Institute for Addiction Science.

How alcohol use changes the brain

Alcohol is addictive and contributes to 2.6 million deaths globally each year, in part by increasing the incidence of heart disease and cancer.

"In my opinion, there's no safe quantity for alcohol," Dr. Maurice O'Farrell, an obesity researcher and founder of the Medication Weight Loss Clinic in Dublin, told Live Science. "If you drink regularly, it's like smoking regularly."

And many people develop alcohol use disorder (AUD), a medical condition defined by continued drinking despite negative consequences.

When this occurs, alcohol's effects, such as feelings of pleasure or the numbing of bad feelings, spur the brain to release the chemical dopamine to the nucleus accumbens, the brain's reward center. This strengthens the motivation to drink. Over time, the decision changes from being a conscious choice, processed in the prefrontal cortex, to a habit governed by the basal ganglia, according to the National Institute on Alcohol Abuse and Alcoholism.

"If you superfeed that limbic system," the part of the brain that seeks instant gratification, "it becomes so strong, it essentially enslaves your frontal cortex," which controls higher-order cognitive functions like planning, decision-making and self-control, O'Farrell said.

GLP-1 receptor agonists work by mimicking the hormone GLP-1 (glucagon-like peptide-1), which acts in the brain to promote feelings of fullness after eating. So it's plausible that these drugs are also affecting the brain in ways that could influence alcohol consumption, experts told Live Science.

Weight loss drugs show promise

But only a handful of human trials have looked at the effects of these drugs on alcohol use. For example, research presented at the 32nd European Congress on Obesity in Spain in May showed that semaglutide cut weekly drinks in 179 people with overweight or obesity who consumed more than 10 units of alcohol a week, or the equivalent of five beers per week. Among regular drinkers, the study found, their drinking dropped from about 23 units to about eight units per week — an over 65% reduction.

But the study didn't randomly assign people to take a placebo or a weight loss drug, so factors other than the weight loss drugs may have caused the participants to drink less. In addition, the research relied on people's estimates of their own drinking, which can be unreliable, so more rigorous trials are needed.

In another study, published earlier this year in the journal JAMA Psychiatry, researchers reported the results of a randomized, placebo-controlled trial, which can do a better job of telling researchers whether the weight loss drugs are playing a role in how much alcohol people drink. In the trial, 48 adults with AUD who were not seeking treatment received weekly injections of semaglutide and were assessed in a laboratory setting.

In lab tests, people taking semaglutide drank less alcohol — and said they felt fewer cravings — than the people who were given a placebo. Although the medication didn't reduce how often people drank, it lowered the amount they said they drank in each sitting.

"It's interesting that we saw these reductions in people who are not trying to reduce their drinking," Hendershot said.

How does it work?

Although research on the topic in humans is still limited, "there's a fairly extensive history of animal research showing that GLP-1 receptor agonists can reduce alcohol intake," Hendershot said.

A 2023 study in rodents published in the journal eBioMedicine found that semaglutide blocked alcohol-induced dopamine release in the brain. This could mean that the drugs act by preventing alcohol from overwhelming the limbic system, and thus dampen the rewards the brain feels after drinking alcohol, the study suggests. And indeed, the animals drank less alcohol when given semaglutide. Alcohol also affects inhibitory brain cells, which help regulate impulse control. GLP-1 drugs may help counteract some of these effects, according to a 2023 study on rats published in the journal JCI Insight.

However, humans are much more complex than rodents. And while scientists are learning more about the underlying mechanisms of action for GLP-1 drugs, it may be some time before researchers fully understand how these drugs work, Dr. Michael Weaver, a professor of psychiatry and the medical director of the Center for Neurobehavioral Research on Addictions at UTHealth Houston, told Live Science.

If you are prescribed these drugs for approved conditions like diabetes, obesity or heart disease, reduced alcohol cravings may be a welcome perk, O'Farrell said, but it's still too early to recommend GLP-1 drugs solely for alcohol use disorder.

"We have medications [for AUD] that are available and known to work," Weaver said, referring to drugs like naltrexone, acamprosate and disulfiram. "Help is readily available. You don't have to wait for a miracle drug."

Editor's Note: This article was updated on Wednesday, May 28 to correct the spelling of Christian Hendershot's name in two instances.

This article is for informational purposes only and is not meant to offer medical advice.

For most of her life, Alyssa Fraser took comfort in cooking. Fraser, a former food reporter from Minnesota, used to relish the process of whipping up her favorite chicken and vegetable recipe or batches of pasta. But after she started taking the popular weight-loss medication Wegovy, her culinary interests seemed to disappear because she became disinterested in food — and certain types of food became particularly off-putting. Many savory meals lost their appeal, and some proteins began to taste too much like the "barnyard" the animal came from, she says. Even her favorite wine, which usually tasted crisp and citrusy, seemed weirdly "vegetal."

Similar to Fraser, other users of Wegovy (known in its generic form as semaglutide), along with those of Ozempic (a form of semaglutide used to treat type 2 diabetes), Zepbound (known generically as tirzepatide) and other medications broadly called glucagonlike peptide 1 (GLP-1) receptor agonists, have described peculiar changes in the way food tastes. GLP-1 drugs — initially designed to help treat type 2 diabetes by triggering insulin release — can cause weight loss by making people feel full faster. But some people report that in addition to an increase in satiety, they experience changes in their preferences for specific foods — they find meats suddenly repulsive, fried foods too heavy and savory snacks unappealing. On online forums and in scientific surveys, some people have expressed a general loss of interest in food overall — a few have even said that the drugs have redefined food as a necessity rather than a joy for them. These accounts may even be captured in grocery store data that suggest people on GLP-1 medications spend less on food, especially calorie-dense and processed items.

Some preliminary evidence suggests changes in food preferences might play a role in weight loss, but it's not clear how much such changes contribute to that result compared with the medications' effect on satiety. And research on the phenomenon has mostly involved animal models or small studies of humans. Experts, however, are starting to gain some clues as to how common these apparent shifts in food preference and taste really are among users and what might be behind them.

Related: Ozempic in a pill? New oral drug may work as well as Ozempic-style injectables

A recent study published in Food Quality and Preference found that people on GLP-1 medications reported reaching for processed foods, as well as refined grains and beef, less often. They also said they were drinking less soda and other sweetened drinks and increasing their intake of fruit, leafy greens and water. Further, they reported consuming about 700 fewer calories per day. These findings rely on self-reported data, however, which can sometimes be unreliable, says Brandon McFadden, a professor in food policy economics at the University of Arkansas and co-author of the study.

Additionally, although GLP-1 users reported eating fewer calorie-dense foods, most people didn't necessarily lose all desire for them. This is because liking a food is different from wanting it, says John Blundell, an emeritus professor in psychobiology at the University of Leeds in England, who was not involved in the recent paper. A person might not find a food particularly tasty (in other words, they might not enjoy the specific sensory experience of consuming it) but still have a strong behavioral drive to eat it. GLP-1 medications seem to involve the reverse: people still like certain foods but have less of an immediate urge to eat them.

These drugs mimic a hormone called GLP-1, which the gut naturally secretes in response to food and which binds to the hormone's receptors around the body — including in brain areas involved in appetite regulation and in reward pathways that reduce the pleasure response to food. Researchers have found that this is the primary way the drugs cause people to lose weight, and some think it might be involved in altered food preferences.

Desires for specific foods can change depending on whether a person is generally hungry or full. For example, when you're hungry, you're more likely to want meaty, high-protein or sometimes high-fat foods rather than sweet ones, Blundell explains. "When you become full, the reverse happens," he says: a big piece of meat or a high-fat food becomes aversive — but you might feel like you have a so-called second stomach for dessert. One plausible explanation for this, Blundell says, could be that GLP-1 drugs' satiating effect simply makes such end-of-meal preferences kick in. It's also possible that some aspects of the drugs' compounds could directly act on specific food preferences through some other biological mechanism. "But it hasn't been demonstrated," says Blundell, who is working with a food company to develop foods that are more palatable for people on GLP-1 medications.

Blundell led a small study, published in 2017, that found people taking semaglutide not only reduced their overall daily food intake but also preferred and consumed fewer high-fat and savory foods. Previous research that he published in 2007 showed that being full also diminishes similar cravings.

But satiety alone may not fully explain the shift in eating preferences. Emerging evidence and anecdotal user accounts suggest changes to the body's taste mechanisms could also play a role. Some users describe flavors becoming stronger or unpleasant while on the medications, though individual experiences seem to vary: Siobhan, a Los Angeles–based writer, who has been taking Wegovy since 2021 and withheld her last name for privacy, says she still finds fatty foods such as French fries appealing — but her favorite food, panang curry, has become too bitter. "I've been eating that curry for 20 years," Siobhan says. "It just didn't taste right anymore." Two-year Wegovy user Sarah Streby says she can no longer stomach eggs or broccoli, and her love for spicy food has waned — causing her to change how she cooks for her family. "Now everyone's complaining the food is too mild because [I] can't handle the spice," she says.

At press time, Novo Nordisk, the manufacturer of Wegovy and Ozempic, had not responded to a request for comment from Scientific American. A spokesperson for Eli Lilly, which makes the weight-loss drug Zepbound, told Scientific American in an e-mail, "We do not have data to share concerning changes in food taste or preference among individuals taking GLP-1 medications." The spokesperson added that known side effects are listed on the medication's labels and that anyone experiencing those side effects should contact their health care provider.

Scientists have found GLP-1 receptors in human taste buds, which hints at a possible explanation for alterations in taste, but findings remain mixed. Some past research has found that people with a higher body weight tend to perceive flavors less intensely, and some evidence suggests this may prompt people to eat more in an attempt to get a bigger sensory reward. In the case of sweet foods, people with a higher body weight also may be less able to perceive a high sugar content, though findings on this have been contradictory. A small study presented at the Endocrine Society's 2024 annual conference found that women taking semaglutide were more sensitive to taste compared with those on a placebo. Brain scans showed increased activity in a region involved in processing sensory rewards when participants tasted something sweet, suggesting that semaglutide may heighten taste perception and make certain foods less appealing.

But another study published in March in Physiology & Behavior seems to suggest the opposite. It found that 46 people taking these medications experienced a reduced sensitivity to all five basic tastes — sweet, sour, salty, bitter and brothy (or umami) — compared with people in a control group. Past studies in mice linked the activation of GLP-1 receptors to alterations in sweet taste perception, but researchers were surprised to see that the effect in humans was broader than anticipated, says Richard Doty, director of the Smell and Taste Center at the University of Pennsylvania and co-author of the March paper. Previous research that linked GLP-1 medications to alterations in taste has mostly looked at diabetic populations, Doty says, adding that "the focus has always been on sugar, and so people haven't looked at the other sensory systems any great detail." He suspects the GLP-1 receptors found in taste buds are behind the March findings, "but we really don't know; there needs to be more research on that."

For some, the drugs' effects on satiety and taste are welcome changes that make it easier to eat less. But for others, it's more complicated. "Not only am I not cooking or really taking an interest in food — if I want it, it's sweets," Fraser says. "And even then, if it's super sweet, I'll take a bite or two, and I'm like, I gotta put it down." She says savory foods have lost their appeal entirely.

Fraser is still considering the trade-offs for the improvements she's seen in her health as she navigates this shift and deals with the loss of a loved hobby. But "the mental load of weight loss has been greatly reduced," she says, "and that is worth it to me."

This article was first published at Scientific American. © ScientificAmerican.com. All rights reserved. Follow on TikTok and Instagram, X and Facebook.

The patient: A 54-year-old man in Rotterdam, Netherlands

The symptoms: The patient visited the emergency room after experiencing shortness of breath, as well as excessive sweating, urination and thirst, for eight days. His abdomen was swollen and distended.

What happened next: Two days before being admitted to the ER, the man had visited his regular doctor, who revealed that the patient had elevated blood sugar in a range hinting at new-onset diabetes, also called "diabetes de novo."

The doctor prescribed metformin, a medication for lowering blood sugar. However, the patient's symptoms did not improve, and his breathing difficulties and abdominal discomfort worsened. Later, at the ER, the man revealed that over the past two days, he had drunk nearly 6 gallons (22 liters) of whole milk per day "to quench his thirst," the doctors wrote in a report of the case.

When the ER physicians drew blood samples, they noticed that the man's blood was paler than normal and "seemed to be milky." His blood sugar levels were extremely high: 1,350 milligrams per deciliter. (Normal glucose levels are typically 70 to 99 milligrams per deciliter.) His triglycerides — a type of fat in the blood — were also dramatically elevated, at 16,713 milligrams per deciliter; normal triglyceride values are typically no higher than 175 milligrams per deciliter, according to the report.

The diagnosis: The doctors concluded that by drinking excessive amounts of full-fat milk, the patient had flooded his circulatory system with fats and sugar and sent his triglycerides skyrocketing, which, in turn, worsened his gut pain and affected his breathing. Extremely high triglycerides can lead to chylomicronemia syndrome, a condition associated with breathing trouble and abdominal pain. The syndrome can also cause memory loss, pancreatitis (inflammation of the pancreas) and discoloration of the retina.

The treatment: Because the man's glucose levels were so high, he was admitted to the intensive care unit and given saline and insulin, the hormone responsible for shuttling sugar into cells. His abnormally elevated triglycerides put him at risk for acute pancreatitis, so the doctors initiated a plasma exchange to clear out the extra fat. They performed two plasma exchanges over the next two days, which reduced the patient's triglycerides to an acceptable level.

The man continued to receive insulin and metformin, as well as a statin medication to prevent cardiovascular disease by lowering cholesterol. The doctors also proposed lifestyle changes for managing his sugar intake. At a follow-up visit six weeks later, the man's triglycerides were still slightly elevated — at 245 milligrams per deciliter — but otherwise, he was in good health.

What makes the case unique: Milk is rich in calcium, protein, magnesium and vitamins A and D, and moderate servings are thought to be beneficial, except for people who are lactose intolerant. That said, the U.S. Department of Agriculture's dietary guidelines recommend no more than 3 cups (0.7 liters) of dairy per day for adults (and some dietitians argue that even that amount is too much).

But the ER doctors estimated that, based on the nutritional value of whole milk, their patient had likely consumed 70 ounces (1,980 grams) of sugar and 53 ounces (1,496 grams) of fat during his two-day binge. To put that into perspective, the recommended daily allowance of sugar for adult men is 1.3 ounces (36 grams), and daily intake of saturated fats, such as those found in whole milk, should be limited to less than 0.8 ounces (22 grams).

As a result of his overindulgence, the astronomical elevation of the patient's triglycerides "is one of the highest ever reported," the doctors wrote.

This article is for informational purposes only and is not meant to offer medical advice.

Drinking alkaline water has become a popular trend, with many companies claiming it offers a variety of benefits, from improved hydration to chronic disease prevention.

But what is alkaline water, and does it actually have any benefits?

"The claims are not justifiable," Salome Kruger, a professor of nutrition at the Centre of Excellence for Nutrition at North-West University at Potchefstroom in South Africa, told Live Science.

Substances that are alkaline are basic, or the opposite of acidic — they have a high pH, while acids have a low pH. Lower pH levels reflect a higher quantity of positively charged particles. Alkaline water usually has a pH level between 8 and 9, higher than that of regular drinking water, which is typically "neutral" at around 7.

Water can become alkaline when it flows over rocks and picks up alkaline minerals, or it can be produced artificially through electrolysis — a process in which filtered water passes through a device that separates the water into alkaline and acidic streams. The alkaline stream contains minerals like calcium, magnesium and potassium.

Related: Why does drinking water feel so good when you're thirsty?

When consumed, it's unlikely alkaline water has any long-lived impacts on the body. That's because the moment it comes in contact with the stomach, its pH is neutralized by the acidity of the gastric juices — which has a pH of 1.5 to 3.5.

The bicarbonate in the water reacts with gastric acid to form water and carbon dioxide, which is then burped out. The minerals in the water are absorbed in the small intestine and enter the bloodstream, where pH is tightly maintained between 7.35 and 7.45 thanks to the lungs and kidneys. Excess minerals in the blood are filtered out by the kidneys and excreted.

Thus, drinking alkaline water is unlikely to significantly "alkalize" the body. What's more, scientific studies on possible health effects of alkaline water are limited and often inconclusive, Kruger said.

Test-tube studies suggest that alkaline water can inactivate human pepsin, a digestive enzyme. In acid reflux, pepsin reaches the throat and damages tissue, so in that context, inactivating pepsin might sound beneficial. But in the stomach, this could potentially disrupt digestion, which would be undesirable, Kruger explained.

Animal research has shown potential benefits, such as increased life span and weight loss, in animals that consumed alkaline water for long periods of time. But researchers could not explain the mechanisms behind these effects, so it's unclear if they're applicable to humans.

One observational study of over 300 women found that those who regularly drank alkaline water had lower body mass indexes (BMIs), blood sugar levels and blood pressure than those who drank normal water. But the former group also had higher incomes, better nutrition and more physical activity. "These lifestyle factors are known to have a much stronger impact on chronic disease risk than simply drinking alkaline water," Kruger said.

There is also no conclusive evidence that alkaline water hydrates better than regular water. In a 2016 study, researchers saw a reduction in blood viscosity — the thickness and stickiness of blood — in people consuming alkaline water and suggested this may reflect better hydration. However, other studies that tracked direct markers of hydration did not find any significant differences between alkaline and regular water.

Related: Boiling tap water can remove 90% of microplastics

Broadly, methodological issues in some of these human studies, such as small sample sizes and a lack of baseline measurements, make it difficult to draw firm conclusions, said Lize Havemann-Nel, an associate professor at the Centre of Excellence for Nutrition at North-West University at Potchefstroom in South Africa.

There is some emerging research that hints alkaline water may act as an antioxidant, reducing oxidative stress and muscle damage from high-intensity or long-duration exercise. But she cautioned that this work is still in the early stages. If alkaline water does have any benefits, these may be more related to its electrolyte content than its pH, Havemann-Nel suggested.

Taken together, the available evidence suggests alkaline water has few, if any, clear benefits over regular water — and drinking it can carry some risks, Kruger said.

For instance, drinking water with a pH above 9 might pose risks for people taking drugs that block stomach-acid production, such as proton pump inhibitors, because it can further raise the stomach's pH levels. Plus, excess minerals from alkaline water could disrupt mineral levels in the blood of people with kidney disease, who can't effectively filter the minerals out.

If an alkaline-water product contains sodium bicarbonate, as some do, it could also contribute to excessive sodium intake. "Many people already consume high sodium levels from table salt and processed foods, so additional sodium from alkaline water might exacerbate this issue," Kruger said.

This article is for informational purposes only and is not meant to offer medical advice.

Alcohol is responsible for about 100,000 cases of cancer and 20,000 cancer deaths per year in the United States, making it the third-leading preventable cause of cancer after tobacco and obesity. In 2025, the U.S. surgeon general issued an advisory on the link between alcohol and cancer risk, calling for a warning to be added to the labels of alcoholic beverages.

But exactly how does alcohol cause cancer?

Research suggests that alcohol drives cancer by at least five different mechanisms, with the risk of cancer increasing the more a person drinks. And the carcinogenic effects of alcohol may be more pronounced in people with a genetic predisposition to cancer.

Alcoholic drinks contain ethanol, also called ethyl alcohol, and this is central to the first mechanism by which alcohol causes cancer. Ethanol can disrupt DNA methylation, a process in which molecules latch on to DNA molecules and thus determine whether a gene is active. There are genes responsible for suppressing tumor growth, and research shows that methylation of such a gene effectively "turns it off," leading to tumor development.

Related: What counts as binge drinking?

Ethanol remains problematic even as the body begins to break it down. Initially, an enzyme turns it into a chemical called acetaldehyde.

"Both ethanol and acetaldehyde are carcinogenic and when they touch the lining of the mouth, throat or esophagus, that can cause cancer," Dr. Noelle LoConte, an associate professor of medicine at the University of Wisconsin School of Medicine and Public Health, told Live Science in an email. Like ethanol, acetaldehyde can also disrupt DNA methylation.

In addition, acetaldehyde directly damages DNA and hinders DNA synthesis and repair. Because DNA provides the instructions for cell growth, damaged DNA can cause cells to grow uncontrollably, leading to the formation of a tumor. Cells in the mouth and liver, where alcohol gets broken down into acetaldehyde, are at particular risk of this type of DNA damage.

A third mechanism involves harmful molecules called reactive oxygen species (ROS). These molecules are natural byproducts of cell metabolism, but if too many accumulate, that can cause oxidative stress that damages DNA.

Research has shown that heavy alcohol use increases levels of the enzyme CYP2E1 in the esophagus; normally, the enzyme is metabolizing drugs. High levels of CYP2E1 increase the production of DNA-damaging ROS, leading to gene mutations and tumors. ROS also disrupt cell behavior, causing cells to multiply and spread uncontrollably. In the liver, ROS trigger the production of inflammatory substances and the fibrous protein collagen, leading to scarring of the liver (cirrhosis). This then increases the risk of liver cancer, LoConte said.

A fourth mechanism linking alcohol to cancer involves alcohol's effect on levels of the hormone estrogen.

"Alcohol raises the blood levels of estrogen … which is 'fuel' for some types of breast cancer," LoConte explained. Scientists think that when tumor cells have a receptor that estrogen can plug into, estrogen latches on and can make the tumor cell more active, revving up its growth and spread. Research suggests that alcohol can trigger the formation of breast tumors and also exacerbate existing breast cancer.

A fifth mechanism linking alcohol to cancer suggests alcohol can act as a solvent for carcinogenic molecules from other sources, such as tobacco smoke. These harmful particles dissolve in alcohol, and this makes it easier for them to penetrate various tissues and cause DNA damage within them. This effect increases the risk of cancer in the mouth and throat, in particular.

Compared with cancers of the mouth, throat and liver, the link between alcohol and cancers of the colon and rectum "is less clear," LoConte noted. "But we think it may have something to do with folate metabolism."

Folate is an important nutrient that helps make blood cells and is also involved in DNA methylation. But drinking too much alcohol can reduce folate levels in the body. This alcohol-induced folate deficiency may lead to DNA damage and, consequently, cancer.

Interestingly, a study found that people who drank alcohol but also had high folate levels through diet and supplementation had a lower risk of developing liver cancer, compared with people who drank but had low folate. And several studies suggest that, in people who consume medium-to-high amounts of alcohol, high folate intake might help guard against colon cancer.

You might wonder if these mechanisms differ depending on the type of alcoholic drink you consume — but research suggests that the connection between alcohol and cancer risk exists for all types of alcoholic beverages.

That said, studies show that the more you drink, the higher the risk of cancer LoConte said. The American Society of Clinical Oncology and U.S. Surgeon General have also highlighted that the length of time you've been drinking over a lifetime is also an important factor.

"But notably, even at lower amounts of drinking, there is still some increased risk for breast, head and neck cancers," LoConte noted.

In other words, when it comes to alcohol and cancer, there's truly no safe dose. This doesn’t mean that everyone who drinks any amount is guaranteed to get cancer. Rather, a person's risk of developing cancer depends on many factors, like their family history of the disease, overall health status and their lifestyle habits, such as smoking or diet. On average, however, studies find that cutting back on alcohol consumption helps to lower the risk of cancer.

This article is for informational purposes only and is not meant to offer medical advice.

The U.S. Food and Drug Administration (FDA) will no longer allow red dye No. 3 to be used in food, drinks or ingested drugs, like cough syrup, the agency announced Wednesday (Jan. 15).

In its announcement, the FDA cited the Delaney Clause — part of the Federal Food, Drug and Cosmetic Act — as the reason for its decision. This clause requires that the FDA ban food and color additives that are found to cause cancer in humans or animals.

In this case, "or" is the operative word in that clause. In several studies, red dye No. 3 was linked to cancer in male lab rats, but these cancer-causing effects have not been seen in other animals or in humans, the FDA noted.

Nonetheless, those rat studies compelled the FDA to ban the additive from cosmetics and topical drugs back in 1990, The Washington Post reported at the time. That decision had followed a petition that asked the FDA to look into these specific uses for the dye. In the end, the agency also cited the Delaney Clause when removing the additive from cosmetics and topical drugs, and now, it has applied the same logic to foods and ingested drugs.

Related: What is brominated vegetable oil, and why did the FDA ban it in food?

One of the rat studies involved feeding 70 male rats very high doses of red dye No. 3, equivalent to 4% of their diets over a lifetime. Fifteen of the rats developed tumors of the thyroid, a gland in the throat, but most of the tumors were not cancerous. Tumors did not show up in male rats fed lower doses of the dye or in female rats fed any dose. And when scientists did the experiment in mice, rather than rats, they didn't see tumors in males or females.

Later studies suggested that the tumors stemmed from a specific hormonal change triggered by the accumulation of red dye in male rats. But that hormonal mechanism is only relevant to rats, the Post reported.

In short, "the way that FD&C Red No. 3 causes cancer in male rats does not occur in humans," the FDA emphasized in its announcement. What's more, "relevant exposure levels to FD&C Red No. 3 for humans are typically much lower than those that cause the effects shown in male rats." The available evidence therefore suggests that ingesting red No. 3 does not put humans at risk.

However, "it doesn't matter, because the FDA mandate under the Delaney Clause says that if it shows cancer in animals or humans, they're supposed to keep it from the food supply," Jennifer Pomeranz, an associate professor of public health policy and management at New York University's School of Global Public Health, told CNN.

As such, the FDA has banned the dye "as a matter of law," its statement says.

Red dye no. 3, also known as erythrosine, gives products a bright, cherry-red color. The FDA noted that the dye is found in some candies, cakes, cookies and frozen desserts, among other products, but that it's not as common as other food dyes.

Specific brands of fruit cocktails, lollipop rings, beef sticks and candy corn are among the foods that contain the dye, according to a database compiled by the Environmental Working Group (EWG), a consumer advocacy nonprofit.

The EWG, which has a sister lobbying organization called EWG Action Fund, was a vocal proponent of the red dye No. 3 ban. In 2022, it and other organizations petitioned the FDA to reevaluate the additive, asking the agency to specifically consider the Delaney Clause. (The EWG has historically drawn some criticism for exaggerating the dangers of various chemicals in food and the environment.)

Any U.S. food manufacturers who use red dye No. 3 will have until January 2027 to reformulate their products, while drug manufacturers will have until January 2028. Products imported into the country also must comply with the ban.

This article is for informational purposes only and is not meant to offer medical advice.

If a recipe asks you to add a bay leaf, would you listen? The leathery but delicate leaf, which is usually removed before a dish is served, has been a mainstay of Mediterranean cuisine for centuries — but recently some food enthusiasts and chefs have questioned if the herb adds any flavor at all.

Could they be right? The answer depends on a number of factors, including the variety of leaf, how fresh it is and even whether people are able to taste its unique flavors, as research suggests that not everyone can.

What do bay leaves taste like?

Bay leaves come from the bay laurel tree, an evergreen tree native to the Mediterranean region. When they're cooked in a meal such as a stew or soup for an extended period, bay leaves are supposed to impart a strong flavor: a mix of pine, clove, lavender and eucalyptus notes, Charles Spence, a professor of experimental psychology and a gastrophysicist at the University of Oxford, wrote in a 2023 paper on bay leaf taste and history.

Related: Why do people like spicy food?

But the subtle green and bitter flavors that leach from the leaf are difficult even for chefs to describe, and some say it has an indescribable mystique. "My brother, who is a chef, is of this opinion," Spence told Live Science. "He feels the dish misses something without the bay leaf even though he can't articulate exactly what the bay leaf does."

Someone unfamiliar with bay leaf's flavor profile may miss the herb's subtle influence and claim it's done nothing, said Ethan Frisch, co-founder and co-CEO of Burlap and Barrel, a single origin spice company.

On top of that, different varieties of bay leaves have different aromas. The European variety (Laurus nobilis L.) is most commonly available in grocery stores and called for in recipes, Frisch noted. But North America is also home to the native California bay leaf (Umbellularia californica). While the two leaves are similar in shape and aroma, the California bay leaf is "a little more piney and citrusy, compared to the Mediterranean species which has more menthol and eucalyptus," according to Frisch.

Perhaps that's why bay leaves are under more scrutiny in North America. Elsewhere, like in the bay leaf's native Mediterranean region, the herb is still a ubiquitous and unquestioned part of the culinary landscape, Spence said.

Frisch said the bay leaf's reputation has been skewed by a combination of poor quality and lack of familiarity. In the U.S., "most dry bay leafs don't have flavor because they're really old," Frisch told Live Science.

Many bay leaf products have unknown harvest conditions and years-long processing times, he said, adding that they can easily be stale before they're purchased.

Cooks may deem the bay leaf's subtle flavor enhancements a poor pay off compared to more pungent spices, like pepper or garlic. They opt to skip or replace it, perpetuating the idea that it doesn't do anything since their dish may still seem fine afterward.

The bay leaf controversy may also be driven by a genetic factor. The volatile compound 1,8-cineole is the most common essential oil in the bay leaf, giving it a medicinal aroma that is somewhat minty, like Vicks VapoRub. A 1981 study in 85 participants found that one-third were unable to taste the 1,8-cineole. It's unknown if the inability to taste bay leaf is genetic, as it likely is with people who think cilantro tastes like soap. This selective anosmia for bay leaves could also help explain why a cohort of people call the herb tasteless, Spence said.

How to use bay leaves correctly

Experts say there are some best practices to make sure you're maximizing the bay leaf effect. Frisch recommends starting with high-quality leaves. Look for brighter green leaves with obvious veins running from the stem through the leaf, and avoid leaves that are grey, brown or have withered stems, as these are signs that the herb has passed its prime.

Whole bay leaves work best for dishes with long cook times, such as soups, stews or braises. Be sure to add the leaf early in the process, allowing it time to release its essential oils. And since most of the volatile compounds in bay leaves aren't water soluble, you'll have the best luck cooking the bay leaf in an oil or fatty base like bechamel, Spence said.

However, for quicker meals, Frisch prefers ground bay leaf. The ground version has more surface area and releases the flavors faster, removing the need for long cook times. And there's no need to remember to take it out at the end of cooking, like cooks have to do with whole leaves. Plus, it can be easier to cook with the ground bay leaf because it's easier to smell the different flavor notes, he said.

But if you don't have quality bay leaves on hand, that's fine. There are some easy substitutes. Frisch recommends using rosemary, thyme or oregano, which have similar herbal notes.

During the festive season and other times of celebration, alcohol often flows freely. But how much is too much?

In short, what counts as "binge drinking," and what are the potential health effects?

Most people understand binge drinking as "drinking to get drunk," said Dr. Ryan Marino, a toxicologist and associate professor at Case Western Reserve University. But the National Institute on Alcohol Abuse and Alcoholism (NIAAA) offers a more precise definition.

Binge drinking refers to when a person consumes enough alcohol within about two hours to raise their blood-alcohol concentration (BAC) to 0.08% or higher. That's at least 0.08 grams of alcohol per deciliter of blood, and for average adults, it's about four or more drinks for women and five or more drinks for men. In the U.S., a standard drink contains 0.6 ounces (14 grams) of pure alcohol; that translates to about 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of distilled spirits.

The binge-drinking threshold is lower for women because their bodies generally have more fat and less water than men of the same weight. Because alcohol dissolves in water, not in fat, women therefore reach a higher BAC than men after drinking the same amount.

Related: What does alcohol do to the body?

Notably, there's a behavior that's even more extreme than binge drinking, known as high-intensity drinking. The NIAAA defines this as drinking at levels two or more times the thresholds for binge drinking — so 10 drinks or more for men, or eight or more for women, within about two hours.

What are the health risks of binge drinking?

In the short term, since alcohol slows brain activity, a person's reflexes after binge drinking are slower than normal, which can lead to accidents such as falls, drownings and car crashes. This suppressed brain activity also makes people more likely to engage in risky behaviors, such as unsafe sexual activity or violence, said Sarah Church, a psychologist and CEO of Wholeview Wellness, an addiction treatment center in New York City.

Drinking too much alcohol in a sitting impairs the hippocampus, a brain area critical for forming memories. This can result in blackouts, preventing a person from recalling what happened while they were intoxicated.

When alcohol levels in the bloodstream become excessively high, areas of the brain responsible for vital functions — such as breathing, heart rate and alertness — also begin to shut down. This is called alcohol poisoning, and it can lead to vomiting, seizures, coma or even death.

Health effects of repetitive binge drinking

A single episode of binge drinking can cause these immediate effects, and likely a hangover the next morning. Repeated binge drinking can have severe long-term effects on both physical and mental health.

It's the liver's job to break down alcohol, so if you drink more alcohol than the organ can process, it can become badly damaged, leading to liver disease. Frequent heavy drinking also affects the heart. Excess alcohol consumption is linked to high blood pressure, and over time, this strains the heart and can lead to cardiovascular disease, increasing the risk of heart attack and stroke.

Long-term heavy alcohol use also damages nerves, sometimes leading to "alcoholic neuropathy." Symptoms include numbness, painful sensations in the arms and legs, and difficulty walking.

There's also sufficient evidence to link heavy alcohol use to higher rates of various cancers. "The rate of cancer of the esophagus, stomach, pancreas, [and] liver is elevated in people who repeatedly drink large amounts of alcohol," said Linnea Axman, the associate dean at the University of Phoenix College of Nursing.

It also disrupts gut health. The gut is home to a large community of bacteria, the "gut microbiome," and "drinking excessive amounts of alcohol can lead to gut dysbiosis, an imbalance of the gut microbiome," said Trista Best, a registered dietitian. That means certain types of gut bacteria become too abundant, while others decline, with negative effects.

Alcohol can simultaneously weaken the gut lining, making it more permeable, which can allow harmful substances to enter your bloodstream, Best added. This can contribute to chronic gut inflammation.

Binge drinking increases the risk of developing an alcohol use disorder (AUD), a disease that causes craving for alcohol, loss of control when drinking and a negative emotional state when not drinking. Not everyone who binge drinks has an AUD, but their increased risk is significant.

High-intensity drinking amplifies all of these risks of binge drinking, said Dr. Rostislav Ignatov, a psychiatrist and chief medical officer at The Haven Detox, a group of addiction treatment centers. In the short term, severe alcohol poisoning or organ shutdown are more likely with high-intensity drinking than with binge drinking. Over the long term, the former accelerates the risk of developing organ damage and cancer typically tied to binge drinking, he said.

"Anyone who is concerned about their drinking should speak to a health care professional to see what treatment options are right for them," said Peter Vernig, a psychologist and vice president of mental health services at Recovery Centers of America.

Treatment options range from inpatient programs, in which you stay at a facility, to outpatient therapy groups and counseling. There are also prescription medications, such as naltrexone, that help to reduce alcohol cravings and dependence. "The most important thing to do is to reach out and start the conversation," Vernig emphasized.

This article is for informational purposes only and is not meant to offer medical or mental health advice.

The patient: A 54-year-old man in Boston

The symptoms: The man was at a restaurant when he suddenly gasped, started shaking uncontrollably and lost consciousness.

What happened next: An emergency medical team performed CPR and determined that the lower chambers of the man's heart were malfunctioning so they could not pump blood properly. The team gave the man drugs to normalize his heart rhythm and keep the heart pumping. The man briefly regained consciousness but passed out again before reaching the hospital.

The diagnosis: Hospital doctors confirmed that the man had experienced cardiac arrest, in which the heart suddenly stops beating.

The treatment: He received IV fluids to stabilize his vitals, as well as drugs to help restart his heart and relieve pain. A tube was inserted into his airway to support his breathing while a mechanical pump was placed to help his heart work. Lab tests revealed that he had too little potassium in his blood, so he was given the essential mineral via IV. Despite these and other treatments, though, the man's condition worsened to multiorgan failure. He died 32 hours after being admitted to the hospital.

What makes the case unique: The cause of this patient's fatal condition might seem harmless: licorice-flavored candy. The man's family informed his doctors that he had been eating one to two large packages of soft candy each day. Three weeks prior to the cardiac arrest, the patient had switched from fruit-flavored to licorice-flavored candy.

Candies flavored with real licorice contain a compound called glycyrrhizin. This compound blocks an enzyme in the kidneys, causing them to retain too much water and sodium and to expel too much potassium. Potassium is needed for the heart to pump properly, so losing too much of the mineral can lead to serious — and sometimes deadly — heart problems.

The Food and Drug Administration warns that "if you're 40 or older, eating 2 ounces (56 grams) of black licorice a day for at least two weeks could land you in the hospital with an irregular heart rhythm." Licorice can also interfere with certain medications, so if you eat this candy, it's best to do so in moderation.

This article is for informational purposes only and is not meant to offer medical advice.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Many people know the feeling that comes after a few too many drinks: a pounding headache, clammy skin, racing thoughts and an upset stomach. Often, these hangovers seem to get worse with age; older people find that the amount of alcohol they used to drink in their youth with no ill effects now leaves them feeling debilitated.

But do hangovers really get worse with age?

Anecdotally, there are plenty of people who would tell you "yes," from personal experience — but there's no hard scientific evidence that hangovers actually intensify with age. However, there are some plausible reasons why they might do so.

"It isn't clear whether hangovers get worse for everyone as they age or just for some people," Aaron White, leader of the National Institute on Alcohol Abuse and Alcoholism's Epidemiology and Biometry Branch, told Live Science in an email. "There simply hasn't been sufficient research on this topic." But nonetheless, there are some theories.

Related: What happens to your body when you stop drinking alcohol?

Hangovers are caused by myriad changes in the body that occur after overindulging. Alcohol is toxic to cells in that it can damage DNA and impede important cellular processes. As it's broken down, alcohol is briefly transformed into a different toxic substance, called acetaldehyde, before being turned into a less-toxic compound called acetate and, finally, into water and carbon dioxide.

As people age, though, the enzymes in the liver that metabolize alcohol and its toxic byproducts can become less efficient, so those toxic chemicals might stick around in the body longer than they used to. When acetaldehyde hangs around in the liver, it can also cause widespread inflammation in the body. Cytokines, the chemical messengers that prompt inflammation, have been tied to malaise, anxiety, irritability and fatigue — all common hangover symptoms.

Plus, compared with young people, older people are more likely to suffer from chronic pain and conditions that cause knock-on inflammation, such as diabetes and arthritis. Thus, drinking too much could result in a double whammy of inflammation on top of an already-high baseline. White said this could "worsen existing physical discomfort" and ultimately result in a more severe hangover.

Both drinking alcohol and experiencing normal aging can make it difficult to stay hydrated, so the combination of the two could be a recipe for a rough morning.

Alcohol is a diuretic, meaning it expels water from the body. Scientists are still debating exactly how much of a role dehydration plays in hangovers, White said, but it's well known that being dehydrated can cause headaches and fatigue, both common hangover symptoms. And after age 60, the overall amount of water in the body starts to decline due to tissue loss. This dehydration not only tees you up for a hangover but could also boost the concentration of alcohol in your blood after you drink, White said.

"It is possible that each drink packs more of a punch as we get older," he said, "which could mean more misery the next day."

Both alcohol and age disrupt sleep, too. Downing a few drinks can speed up the initial process of falling asleep, but it can also undermine sleep quality and cause people to wake up earlier, resulting in a worse night's sleep overall. White said sleep quality tends to decrease with age anyway, so "we might feel the impact of alcohol on next-day fatigue more than when we are younger."

Though there are many potential reasons alcohol could hit harder with age, bad hangovers aren't a guaranteed part of getting older. One survey of more than 50,000 people ages 18 to 94 found that older people actually reported a lower incidence of hangovers after binge drinking, compared with their younger counterparts. The researchers couldn't explain this pattern even when accounting for each age group's usual alcohol consumption or frequency of binge drinking.

These results were echoed in a smaller, self-reported survey that found hangover severity decreased with age. Although younger participants reported drinking more, when the researchers corrected their results for the amount of alcohol consumed, they found that older participants reported less severe and less frequent hangovers than younger people. The researchers theorized that this may be the case because older people become less sensitive to pain over their lives.

While there's still some debate on exactly how aging affects hangovers, White said one thing is clear: The only guaranteed way to avoid a hangover is to avoid drinking too much in the first place.

"Time is the only universal cure for hangover symptoms," White said. "And not overindulging is the best strategy for preventing them."

This article is for informational purposes only and is not meant to offer medical advice.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

It's well known that vegetarians and vegans need to work a little harder to get their protein. Even popular meat replacements often aren't as protein-dense as their animal-based counterparts; for example, tofu has about 8 grams of protein per 100 grams, whereas chicken breast has 31 grams.

But why, on a biological level, does meat generally contain so much more protein than plants do?

According to Christi Calhoun, scientific communication resource officer at the American Meat Science Association, the main reason is that plants and animals have different cellular needs, which result in different cellular compositions.

"Animals store more protein in their tissues because their bodies are designed to support active functions such as muscle movement, energy metabolism, and cellular repair," Calhoun told Live Science in an email. Key molecules in animals' bodies like enzymes and hormones are actually just specialized proteins, and other proteins like actin and myosin make up muscle fibers and enable active movement.

"Plants, on the other hand, rely more on carbohydrates and other molecules for structure and energy storage," Calhoun continued, "so their tissues naturally contain less protein."

While carbohydrates are an important energy source in both plants and animals, they can't complete the same diverse cellular functions that proteins can due to their simpler molecular structure.

But total protein levels don't tell the full story; it's also important to consider the kind of protein. To do that, it's necessary to understand protein on a molecular level.

"One can imagine proteins as "beaded necklaces", each bead made up of different amino acids," Kinga Balogh, a registered dietitian at JM Nutrition in Canada, told Live Science in an email. She said human bodies "string together a wide variety of 'necklaces' from various amino acid 'beads'" to fabricate different proteins for different functions.

There are 20 types of amino acids, and each plays a unique role in cellular processes such as tissue repair, nutrient transport and brain function. Nine of these are called essential amino acids, because the body cannot produce them on its own. Humans need to get essential amino acids through their diet.

Animal-derived proteins contain all nine of those essential amino acids, so they're classified as "complete" proteins. Proteins from plant sources, on the other hand, are often missing one or more of the nine essential amino acids, making them "incomplete" protein sources.

Related: What happens to meat as it's cooked?

What's more, the body processes proteins from animal and plant sources differently.

"Animal proteins, such as those in meat, have higher bioavailability," Calhoun said. That means that the human body can break down and absorb those proteins more easily. Because plant proteins can contain more indigestible materials, like fiber, the body needs to work harder to process that protein.

In 1993, the U.S. Food and Drug Administration and the World Health Organization developed a scale that quantifies different protein sources based on their amino acid composition and overall bioavailability. The scale, called the Protein Digestibility Corrected Amino Acid Score (PDCAAS), outputs a score between 0 and 1, with 1 indicating high protein quality and 0 indicating low.

According to a compilation of PDCAAS scores presented at the International Society of Sports Nutrition Symposium, beef and eggs have scores between 0.9 and 1, black beans get a 0.75 and peanuts are rated 0.52. However, soy — the basis of products such as tofu and tempeh — achieves a plant-based high score of 0.92.

These differences make it difficult to directly compare plants and animal products based only on total overall protein. "Only looking at total protein or 'crude' protein does not tell the full story of a food's impact on human health," Calhoun said.

Although meat tends to have higher overall protein content, more essential amino acids, and more bioavailability, it's still possible to leverage nutritional science to make plant-based proteins more efficient.

"When it comes to vegetarian or vegan diets, folks have the option of combining multiple plant-based foods that contain incomplete proteins," Balogh said. This strategy allows people to combine two or more incomplete proteins to check off all nine essential amino acids. Balogh said examples of these pairings include whole-wheat toast and nut butter, beans and rice, or lentil soup with a whole-grain roll.

Still, Balogh cautioned that "laser-focusing" on protein isn't always the best strategy.

"Our human body performs well when we consume a wide variety of foods in amounts that meet daily requirements consistently," she said. "Proteins function most effectively in the human body when we also consume adequate amounts of energy, carbohydrates and fat."

The old Latin adage "In vino veritas" — meaning "In wine, there is truth" — is just one of a litany of sayings perpetuating the idea that alcohol is a sort of truth serum. The phrase is attributed to Pliny the Elder, a Roman scientist, historian and soldier, though similar aphorisms can be traced back even further, to ancient Greece.

But does alcohol really make people more honest? The answer is both yes and no, experts told Live Science.

Alcohol "makes us more likely to say whatever's on our minds," said Aaron White, leader of the National Institute on Alcohol Abuse and Alcoholism's Epidemiology and Biometry Branch. "In some cases, that could be the truth. In some cases, it could be what you think is the truth in your intoxicated state."

So there's definitely a higher likelihood that someone will speak their mind after a few drinks. But there's also a chance that they will say something that feels real while drunk but that they wouldn't take seriously while sober. For example, a drunk friend might make bold promises they're going to move cities or quit their job only to take them back the next morning.

While an extensive online search didn't turn up any direct results for research on how alcohol influences honesty, studies about alcohol's impact on personality, emotion and cognition help support this idea.

For example, a 2017 study in the journal Clinical Psychological Science explored how participants' personalities changed after they'd consumed enough vodka lemonades to bring them to 0.09% blood alcohol concentration — just over the federal legal driving limit in the U.S. and England. Outside observers remarked that the biggest change in participants' personalities after drinking was that they became much more extroverted. Though the study didn't investigate whether alcohol was a truth serum, it makes sense that someone who feels more at ease in a social setting is also more likely to be candid.

Alcohol's ability to help people come out of their shell may help them say what's on their minds, but White says its effects on emotions can make those thoughts more mercurial.

Related: How a hangover affects your brain the next day

"We generally find that drinking alcohol tends to intensify our emotions," Michael Sayette, a professor of psychology at the University of Pittsburgh, told Live Science in an email. "We may find ourselves smiling more and speaking more loudly in pleasant interactions, but perhaps, as the researcher [professor emeritus at Stanford University] Claude Steele put it, we might also be more likely to cry in our beer in less-pleasant situations."

Those heightened emotions might lead people to say what's on their sober mind, but they can also put someone in a volatile state where they say something they don't really mean or deeply regret later. It's similar to how drinking makes some people more likely to become violent or to gamble — actions that may cross their sober minds, but they would have the wherewithal to avoid.

"Because alcohol can change our thoughts and feelings, it's unsurprising that behaviors can also change," Sayette said. "Alcohol can lead our behaviors to become more extreme."

These effects stem from alcohol's ability to cause disinhibition, which means a person is more likely to act on their impulses. This happens because alcohol dampens signals in the prefrontal cortex, a region of the brain that regulates behavior and controls impulses, White explained.

What's more, alcohol also suppresses the amygdala, a structure deep in the brain known for sparking feelings of fear and anxiety. While a person is sober, the amygdala generally sends out warning signals that can stop a person from saying or doing things that could lead to a social faux paus, but those signals quiet down after a few drinks.

So is there really "veritas in vino"?

Sure, people might be more likely to divulge secrets after a few glasses of wine — but they're also likely to blurt out something they don't really mean and will regret the next morning. The effects of alcohol on the mind are simply too complex to have a black-and-white effect on honesty.

"Alcohol is not a truth serum," White said. "That's for certain."

Researchers have made a breakthrough in the race to save the world's bananas from a devastating disease that could wipe them out, according to a new study.

The bananas we eat, called Cavendish bananas, are threatened by a plant-killing disease called fusarium wilt. This disease has already wiped out other banana varieties, and it devastated banana production in the 1950s.

But in the new study, researchers found that the disease strain threatening bananas today didn't evolve from the strain that caused so much damage in the 20th century and that there may be a way to control its spread.

The team's findings, published Friday (Aug. 16) in the journal Nature Microbiology, could help avert an impending "banana apocalypse," according to a statement from the University of Massachusetts Amherst.

"The kind of banana we eat today is not the same as the one your grandparents ate," study senior author Li-Jun Ma, a professor of biochemistry and molecular biology at the University of Massachusetts Amherst, said in the statement. "Those old ones, the Gros Michel bananas, are functionally extinct, victims of the first Fusarium outbreak in the 1950s."

Related: Why are bananas berries but strawberries aren't?

There are many species of wild banana and we farm numerous varieties. Today, the most common banana found in shops is the Cavendish banana from the species Musa acuminata. Almost all of the global banana exports come from this variety, according to the Royal Botanic Gardens, Kew in the U.K.

Cavendish bananas were bred to resist the strain of fusarium wilt that wiped out Gros Michel bananas. However, a second outbreak of fusarium wilt that did affect the Cavendish variety emerged in the 1990s, and the Cavendish has been under threat ever since. Like bananas, fusarium wilt has many varieties, and each affects a different plant host, according to the statement.

When researchers compared 36 Fusarium strains from around the world, they found that the one causing the current outbreak uses genes that produce fungal nitric oxide to attack hosts, according to the study. The team doesn't know how these genes lead the disease to infect Cavendish bananas. However, they found that the disease's virulence — its capacity to damage a host — was reduced when the genes were eliminated, so reducing the nitric oxide could be key to controlling the disease.

Although the new study could help save our favorite bananas, Ma noted that monocropping — growing the same crop every year — is the underlying problem facing bananas, and they will be vulnerable to disease as long as we continue to rely on a single variety.

"When there's no diversity in a huge commercial crop, it becomes an easy target for pathogens," Ma said. "Next time you're shopping for bananas, try some different varieties that might be available in your local specialty foods store."

Heart disease, cancer, diabetes — these and other concerning health effects have been tied to "ultraprocessed foods," which make up more than half of the calories consumed in the U.S. Eating large amounts of these foods, which are high in salt, sugars and additives, may even increase a person's risk of early death. 

There's growing awareness around the potential harms of these products, but which foods count as "ultraprocessed" is not always clear. 

So what, exactly, are ultraprocessed foods?

Related: What is brominated vegetable oil, and why did the FDA ban it in food?

Define 'ultraprocessed'

Almost all foods are processed in some way, but classification systems distinguish the types of processing they undergo. One commonly used system is the NOVA classification system, which categorizes food into four groups, Adrian Brown, a senior research fellow at University College London, told Live Science in an email. These include unprocessed and minimally processed foods, processed culinary ingredients, processed foods and ultraprocessed foods. 

Unprocessed foods include the edible parts of plants or parts from animals as they're found in nature — for example, fresh, whole heads of broccoli; unsalted seeds; mushrooms; and eggs. Minimally processed foods are slightly altered to make them more suitable or safe to consume, meaning they may be frozen, roasted or dried. Nothing is added to these foods, so they're free of salt, sugar or oil. Examples include frozen peas and roasted coffee beans. 

Next you have processed culinary ingredients, used to season and cook foods and obtained by slightly processing foods from the first group. For instance, vegetable oils can be derived from crushed seeds. 

Processed foods include smoked meats, canned vegetables, tofu and fresh breads. They contain multiple ingredients and increase a food's shelf life, generally by adding processed culinary ingredients, like salt. They're still considered versions of the original foods — for instance, packaged applesauce is made from whole apples.

Ultraprocessing, on the other hand, dramatically transforms ingredients through intensive, industrial methods.

NOVA defines ultraprocessed foods as "formulations of ingredients, mostly of exclusive industrial use, typically created by series of industrial techniques and processes." Examples of ingredients used only in industrial settings include specific sugars, such as dextrose,  and protein sources, such as casein.

Ultraprocessing involves breaking down foods into their component parts, such as starches and oils. These are then chemically modified — to break bonds between their molecules, for instance — and combined with techniques like extrusion, which forces soft substances together into a desired shape. Colors, flavors, emulsifiers and other additives are also used to enhance a food's taste and shelf life.

Ultraprocessed foods include soft drinks, candies, breakfast cereals, chicken nuggets, hot dogs and instant soup powders. They are meant to be convenient to prepare and tasty to consume.

Related: Risk of AFib tied to sugary and artificially sweetened drinks

Dangers of ultraprocessed foods

There are several reasons ultraprocessed foods are bad to eat in excess, Dr. Jennifer Hankenson, who practices physical medicine and rehabilitation at Yale Medicine, told Live Science in an email.

"One is because they have additives that are dangerous to our health and increase the risk of developing chronic health conditions such as diabetes, cancer, heart disease, and high blood pressure," Hankenson told Live Science. Ultraprocessed foods often have an excess of certain ingredients, such as sugar and salt, that make them highly palatable, making it harder for consumers to stop eating at suggested serving sizes, she said. 

The products are also low in fiber, so they're absorbed quickly in the gastrointestinal tract and don't adequately nourish the gut microbiome. In addition, evidence suggests they don't set off the same satiety signals as unprocessed foods do, leaving people feeling hungrier. 

Hankenson said eating small amounts of ultraprocessed foods likely isn't bad for you. However, she noted that no amount would be considered "healthy" or "recommended," per se, especially for people with chronic health conditions.

Erikka Loftfield, an investigator at the National Cancer Institute, said the organization recently conducted a study of more than 500,000 people that linked high ultraprocessed-food intake to a higher risk of all-cause mortality. The research, which has yet to be published, also found a link to death caused by either heart disease or diabetes.

Related: How long does it take to digest food?

Ultraprocessed meats and soft drinks were the products most strongly associated with mortality risk, Loftfield told Live Science in an email.

Importantly, though, "there are a wide range of foods and beverages classified as ultraprocessed foods according to the NOVA system, and it is unclear how each of these foods impacts human health," Loftfield noted.

Brown added that, although these classifications can be helpful, it may sometimes be tricky to tell if a food is ultraprocessed. Food labels, such as those that say "all natural," can be deceptive and are not regulated by the Food and Drug Administration.

If you're interested in getting professional help to better navigate food choices, a dietitian or nutritionist may be able to guide you toward the healthiest choices for you.

This article is for informational purposes only and is not meant to offer medical advice.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Recent headlines denounced plant-based fake meat — such as vegetarian sausages and textured vegetable protein — as unhealthy and claimed that their consumption is linked to an increased risk of cardiovascular disease and death. But a closer look at the study underpinning these claims suggests a more nuanced story.

The real culprits are in fact "plant-based" ultraprocessed foods as a whole, not meat substitutes in particular, according to the paper that kickstarted the headlines. But there's an important caveat: "plant-based" foods include ones you might not expect — such as chocolate-covered biscuits, frozen pizza and sodas. The study, published earlier this month in the Lancet Regional Health–Europe, linked plant-based ultraprocessed foods to an increased risk of cardiovascular-related illnesses and death.

Plant-based meat represented a very small slice of study participants' overall food consumption, however, and the study was not designed to pinpoint exactly which foods had the strongest links to poor health outcomes. Nevertheless, the muddled interpretations show just how complex nutrition research can be, critics say, because food definitions used by scientists don't always reflect what other people might interpret as a plant-based diet.

Foods are described as ultraprocessed when they undergo an industrial transformation that significantly alters the original ingredients. These foods have a long journey before reaching your plate. Pantry staples such as instant noodles and store-bought cookies typically undergo several stages of processing that unravel the internal architecture of their raw ingredients. They are then reassembled in a form that prioritizes convenience and taste — often with a mix of additives designed to enhance appearance and shelf life. A rule of thumb is to "think of a food you wouldn't be able to prepare in your own kitchen," either because of its chemical constituents or the industrial machinery needed to prepare it, says Evangeline Mantzioris, a researcher and dietician at the University of South Australia, who was not involved with the study.

RELATED: Why some plant-based diets are healthier than others

In nutrition research, including in this widely discussed paper, a framework known as the NOVA classification system is used as a benchmark to group foods along a spectrum from unprocessed to ultraprocessed based on the level of alteration from their natural state. Most foods can be categorized intuitively. Broccoli or beans are not considered ultraprocessed, whereas breakfast cereals and canned soups are. Others might not be obvious at first glance, however. For example, the new Lancet Regional Health–Europe study included beer and wine as examples of non-ultraprocessed beverages, but spirits such as vodka were considered ultraprocessed.

The idea behind using this framework in food research is that processing food might fundamentally change how it interacts with the body to influence health, says Fernanda Rauber, lead author of the new study and a nutritional epidemiologist at the University of São Paulo in Brazil. The health effects of food aren't "just from the sum of its nutrient functions," she says. "The way foods are combined, prepared and consumed as meals also plays a crucial role in their health impacts."

In the study, Rauber and her colleagues linked what people ate in a day to their hospital and mortality records related to cardiovascular diseases. The researchers did this using data from more than 100,000 adults in the U.K. BioBank — a large database that tracks the health, lifestyle and genetic information of volunteers between the ages of 40 and 69 in the U.K.

The plant-based category in the study was something of a catchall, says Gunter Kuhnle, a nutritional epidemiologist at the University of Reading in England, who was not involved in the study. When he first read the paper's title, Kuhnle assumed it referred to plant-based meat alternatives, plant-based drinks or plant-based milks — in other words, only the replacements for animal-derived products. "Reading the paper, it became pretty obvious that it was not that," he says. The press release also emphasized that interpretation, specifically stating in the first paragraph that products "intended to replace animal-based foods" — such as plant-based sausages, nuggets and burgers — were linked to the higher risk for cardiovascular illness.

But there's more to the story: meat alternatives were evaluated alongside ultraprocessed foods that were less intuitively "plant-based," including bread, cakes, sugary sodas, potato chips and ketchup — foods that don't immediately come to mind when people think of a plant-based diet, Kuhnle says. Such a broad categorization was "not wrong," he says. "It was just easy to misunderstand."

The study found that the more ultraprocessed foods people consumed, the more likely they were to have or die from heart disease — results that "weren't really that surprising," Kuhnle says, given the inclusion of "plant-based" foods that many dietary guidelines recommend eating in moderation — such as sugary foods or drinks.

As a percentage of total energy intake, for every 10% increase in consumption of plant-sourced ultraprocessed foods — which included foods such as cookies and chocolate bars but also tofu and tempeh — the risk of cardiovascular disease went up by 5%, and the likelihood of dying from the disease rose by 12%. The reverse was also true — for every 10% increase in consumption of foods that were not ultraprocessed but still plant-based — such as pasta, beans and potatoes — the risk of heart disease fell by 7%, and mortality did so by 13%.

The problem is that this type of analysis isn't able to show whether one specific food is worse than another because they're evaluated as a group. Additionally, the tofu, tempeh and textured vegetable protein products categorized as plant-derived, ultraprocessed foods only accounted for a fraction of the total calories that people consumed — about 0.2% in total — whereas other foods such as packaged breads made up 10%. "We cannot draw specific conclusions related to this particular type of food," Rauber says in response to the way the paper has been portrayed in some media coverage.

Nevertheless, the findings add to a growing body of evidence linking ultraprocessed foods to negative health outcomes. A recent review of multiple studies that included data from a total of almost 10 million people found that eating more ultraprocessed food was associated with a range of health risks, including cardiovascular diseases. The health effects of imitation meat products are less clear cut. One recent study showed that vegetarians and vegans consume more ultraprocessed foods compared with meat eaters and that they preferred unhealthy plant-based foods over healthier alternatives, but it did not examine the long-term health effects of such dietary patterns. On the other hand, ultraprocessed meats themselves, such as sausages and salami, have been linked to higher all-cause mortality and to colon cancer in particular.

Exactly how ultraprocessed foods might cause such health harms is still unclear. Some research points to the high saturations of salt, sugar and fat in these foods as the culprits, but other studies suggest that the act of processing a food — breaking down its natural structures and forming them into something new — could be affecting the body in ways we don’t yet understand. Chemical additives, such as the common flavor enhancer monosodium glutamate (MSG) and contaminants that might appear from frying, baking or fermenting ultraprocessed foods, such as acrolein, might also affect appetite and health; acrolein specifically has previously been associated with higher cardiovascular disease risk.

Rauber cautions that the study could not parse cause and effect. In reality, people's eating habits are messy and don't typically adhere to a strict regimen over a long period of time — making it a challenge to design studies that can draw conclusions about whether certain diets cause disease. But given the number of observational studies available, "there are huge amounts of evidence ... to tell us that ultraprocessed foods are probably not doing the best thing for our health," Mantzioris says. Rauber's study accounted for other variables, such as the effect that family history, physical activity and ethnicity might have on an individual's risk of developing heart disease.

Kuhnle says an ultraprocessed food isn't necessarily a "good" or "bad" choice but should be viewed in the broader context of a person's diet, keeping in mind that the health effects of ultraprocessed food won't develop overnight.

This article was first published at Scientific American. © ScientificAmerican.com. All rights reserved. Follow on TikTok and Instagram, X and Facebook.

Paul Saladino is stripped to the waist, biceps bulging as he works a butcher's saw back and forth across a cow femur. When he finally severs the bone, a crowd of onlookers erupts in cheers. Flashing a smile, he checks to make sure he's being filmed, then scoops a spoonful of marrow from the center of one piece of bone. He then deposits it in the mouth of an eager young woman like a priest giving communion.

Saladino, a medical doctor, is a popular proponent of an animal-based diet that exalts meat and organs and demonizes vegetables. Through videos like this one on TikTok, as well as the podcast he hosts, he preaches the value of eating beef and liver, marrow and testicles to millions of followers on social media. He is the author of the 2020 book "The Carnivore Code" and a companion cookbook. He founded the company Heart and Soil, which sells organ-based supplements, and co-founded Lineage Provisions, which sells protein powder and meat sticks. Saladino contends that the traditional food pyramid, with its broad base of plant foods that narrows into animal foods, is upside down and that the medical establishment's view that high cholesterol causes heart disease is wrong. He says that meat and organs are the key to health, strength and vitality.

Saladino is not alone in his carnivorous pursuits. TikTok, Instagram and YouTube are teeming with influencers peddling meat-centric menus. Like the so-called paleo or caveman diets before them, these diets shun ultraprocessed foods such as potato chips, breakfast cereals, packaged breads, sodas and hot dogs. But they are significantly more restrictive than the paleo diet where plant foods are concerned. Some advocates, Saladino and celebrity adventurer Bear Grylls among them, allow for a limited amount of fruit but discourage vegetables, which they contend are loaded with defensive chemicals that are toxic to humans. Others, such as Canadian psychologist Jordan Peterson and his podcast host daughter, Mikhaila, champion a diet of beef, salt and water alone. Many, like social media personality Brian Johnson, aka Liver King, recommend consuming animal products — including dairy and eggs— raw.

Meatfluencers, as they are known, often charac­terize their regimens as "ancestral," made up of the foods our ancient predecessors ate. If this is what our ancestors ate, they argue, then this is what the human body is supposed to consume. "If you align your diet and lifestyle with millions of years of human and hominid evolution," Saladino says in another TikTok appearance, "that is how humans thrive."

Studies of the remains of our forebears, as well as observations of living primates and modern-day hunter-gatherers, refute the idea that humans evolved to subsist primarily on animals. Meat did play a significant role in our evolution. Yet that doesn't mean we're meant to eat like lions. Real ancestral human diets are difficult to reconstruct precisely, but they were vastly more varied than the mostly meat diets of carnivores, a finding that has important implications for what people today should eat to be healthy.

To be fair to the promoters of flesh-forward diets, scientists have traditionally paid a lot of attention to meat eating in human evolution, as have journalists who write about our origins (including me). Several factors have contributed to this trend. For one thing, we humans are unique among primates in regularly hunting animals that are as large as or larger than ourselves, and scientists are particularly interested in understanding traits that set us apart from other creatures. For another, stone tools and butchered animal bones are more readily preserved in the archaeological record than fragile plant remains. And then there's the fact that the hunting of animals — particularly large, dangerous mammals such as elephants — is inherently more exciting than the quiet business of gathering berries, nuts and tubers. In any case, it doesn't take a lot of googling to turn up a heap of scientific papers and popular articles touting the idea that hunting and eating meat made us human.

Interest in the role of meat and hunting in human origins has deep roots. Charles Darwin even speculated about its importance in his 1871 treatise, The Descent of Man, and Selection in Relation to Sex. Ideas about how carnivory shaped human evolution have shifted over the years, but the prevailing wisdom is this: around two million years ago Homo erectus, an early member of our genus, began evolving modern human body proportions, with longer legs, shorter arms, a smaller gut and a larger brain. The earliest stone tools and animal bones bearing cut marks date to before that period. The timing suggests that the invention of sharp-edged stone tools allowed early humans to butcher large animals and have access to a rich new source of calories. This nutritious food required less processing in the gastrointestinal tract, which allowed our energetically expensive gut tissue to shrink. Calorie-dense meat also provided fuel that allowed our energetically expensive brains to expand. A feedback loop took hold: as brains ballooned, our increasingly clever ancestors dreamed up ever more effective tools for procuring energy-rich animal foods, fueling more brain growth in Homo.

If that were all we knew about human evolution, it'd be tempting to conclude that we evolved to eat a meat-based diet. But that's only a piece of what anthropologists and archaeologists have learned about food and human origins, and even that chapter of our story has undergone revision over the past 15 years in light of new evidence. Fresh fossil discoveries and novel DNA analyses are revealing what our ancestors ate in unprecedented detail. For a clearer understanding of the evolution of humans and our diet, we need to take a closer look at what happened before and after that two-million-year mark.

Let's start at the beginning. Humans, monkeys and apes make up a subset of primates known as the higher primates, which evolved to eat fruit. The hominin lineage (Homo sapiens and its extinct relatives, including Ardipithecus, Aus­tralopithecus, and others) dates to roughly six million to seven million years ago. Fossils of the earliest known hominins indicate that they walked upright on two legs but still spent a lot of time in trees. They don't appear to have made stone tools and probably subsisted on a diet similar to that of chimpanzees and bonobos, our closest living relatives — which is to say mostly fruits, nuts, seeds, roots, flowers and leaves, along with insects and the occasional small mammal.

For the entire first half of our known history, hominins seem to have maintained this plant-based diet — they left no material trace of meat eating. It's not until nearly three million years after our lineage got its start that there's any evidence that they exploited large animals for food.

The oldest possible evidence of meat eating by hominins comes from Dikika, Ethiopia. There researchers found fragments of bone from goat- and cow-size mammals bearing marks suggestive of butchery that occurred at least 3.39 million years ago. The butcher, in this case, was probably Australopithecus afarensis, the small-brained, small-bodied hominin species to which the famous Lucy fossil belongs—the only hominin species known from this time and place. Although no tools were discovered, based on the pattern of damage to the bones, the researchers concluded that A. afarensis used sharp-edged stones to strip flesh from the bones and struck the bones with blunt stones to access the marrow inside.

The oldest stone tools come from the site of Lomekwi in northwest Kenya. Like the cut-marked bones from Dikika, these 3.3-million-year-old implements significantly predate the origin of our genus, Homo, and seem instead to be the handiwork of the small-brained australopiths. Both occurrences also appear to be isolated in time, a flash in the evolutionary pan, separated by the next oldest evidence for stone tools and butchery by hundreds of thousands of years.

It's only after two million years ago that hominins started to incorporate large game into their diet more routinely, according to Briana Pobiner, a paleo­anthropologist at the Smithsonian National Museum of Natural History, who studies the evolution of meat eating in humans. The site of Kanjera South in south­western Kenya, which records hominin activities from around two million years ago, is one of the earliest sites to preserve evidence of what researchers call persistent carnivory. There early members of Homo transported choice rocks from as many as 10 kilometers away to make their stone tools. They used these tools to extract meat and marrow from a variety of mammals that lived in the surrounding grasslands, from small antelopes to bovids the size of wildebeests. Some of the antelopes appear to have been acquired intact, presumably through hunting. The larger animals may have been scavenged. However they procured the carcasses, the Kanjera hominins butchered animals at this site repeatedly, over generations, the bones spanning a sediment layer three meters thick.

The hominins at Kanjera went back to this place again and again to butcher animals, but their pattern of persistent carnivory was not widespread elsewhere. Nor was it followed by a steady increase in meat eating over time, as would be expected in the feedback-loop scenario. W. Andrew Barr of George Washington University and his colleagues, including Pobiner, analyzed the evidence for hominin meat consumption in the zooarchaeological record of eastern Africa from between 2.6 million and 1.2 million years ago. Although the evidence for meat eating increases shortly after two million years ago with the debut of H. erectus, the first hominin to attain modern body proportions, the study found that this pattern is the result of a sampling bias: researchers have simply collected more archaeological material from this time period than from earlier intervals. Their findings, Barr, Pobiner and their co-authors concluded, did not support the hypothesis that meat made us human.

"When I think about changes in diet over time, I don't think the change was linear," Pobiner says. In many ways, the changes have been more about broadening the diet rather than progressing from vegetarian to meat eater, she explains. "Humans are omnivores," she says. "We've always been omnivores."

Even at Kanjera, with its impressive accumulation of butchered bones, meat wasn't the only food on offer. Analyses of the cutting edges of a sample of stone tools from the site revealed that most of the implements exhibit wear patterns characteristic of tools that have been used in experiments to chop herbaceous plants and their underground storage organs — those tubers, bulbs, roots and rhizomes that plants produce to store carbohydrates. A smaller proportion showed signs of animal-tissue processing.

As much as the evolution of meat eating is a focus of her work, Pobiner says, "that doesn't mean that I think that it was ever the most significant component of early human diets."

It's possible that early humans were target­­ing fat rather than meat when they first started butchering animals. Jessica Thompson of Yale University and her colleagues argue that before hominins invented stone tools suitable for hunting large animals, they may have used simpler implements to scavenge abandoned carcasses for their nutritious marrow and brains. Lean meat such as that from wild animals is energetically expensive to metabolize, and in the absence of fat in the diet, it can cause protein poisoning and other ills. Smashing scavenged bones to get to the marrow could have produced the extra nutrients needed to fuel brain growth before our ancestors developed the more complex technology needed for hunting.

The fat and meat of terrestrial mammals weren't the only pos­sible source of extra calories for hungry hominins. Fish, shellfish, and other aquatic animals and plants sustained our forebears who lived near rivers, lakes and oceans. As early as 1.95 million years ago, Homo was exploiting fish and turtles, among other aquatic foods, in Kenya's Turkana Basin.

Our ancestors may have also wrung more calories from plant and animal foods by cooking them. Richard Wrangham of Harvard University has proposed that cooking, which makes food easier to chew and digest, may have provided Homo with the extra fuel needed to power a bigger brain. In 2022 researchers announced that they had found remains of fish that may have been cooked with controlled heat 780,000 years ago at the site of Gesher Benot Ya'aqov in Israel.

There is another place where scientists can look for clues to what early humans ate: their teeth. When researchers analyzed the tartar preserved in the stained teeth of two Australopithecus sediba individuals from South Africa, they found microscopic bits of silica from plants these hominins ate nearly two million years ago, including bark, leaves, sedges and grasses.

Even the Neandertals, our burly cousins who ruled Eurasia for hundreds of thousands of years and are known for having been skilled big-game hunters, consumed plants. Amanda Henry of Leiden University in the Netherlands and her colleagues found traces of legumes, dates and wild barley in the tartar on their fossilized teeth. And researchers led by Karen Hardy of the University of Glasgow discovered roasted starch granules in Neandertal teeth, in­dicating that they ate cooked vegetables. Some Neandertals might have even forgone animal flesh entirely: in a study co-led by Laura Weyrich of Pennsylvania State University, analyses of DNA preserved in the tartar of Neandertals found in El Sidrón cave in Spain turned up traces of pine nuts, moss and mushrooms — and no meat whatsoever.

Researchers have developed other techniques for studying what hominins put in their mouths and chewed, such as measuring the chemical isotopes in teeth, but these methods have important limitations: they can't determine the proportion of animal versus plant foods in the diet. To that end, another tartar study offers an inkling. James Fellows Yates of the Max Planck Institute for the Science of Human History and his colleagues analyzed DNA from bacteria preserved in Neandertal tartar and compared it with bacterial DNA from the teeth of modern chimps, gorillas, howler monkeys and modern humans. The team found that the Neandertals and modern humans in their sample had a group of Streptococcus bacteria in their mouths that the nonhuman primates didn't have. These strep bacteria eat sugars from starchy foods, such as roots, seeds and tubers. Their presence in the mouths of the Neandertals and modern humans — but not the nonhuman primates, which eat mostly nonstarchy plant parts — indicates that Homo had adapted to eating an abundance of starchy plant foods by the time Neandertals and modern humans split from their last common ancestor around 600,000 years ago. This timing hints that a high-carb diet helped to power brain expansion in Homo.

Other features of teeth suggest additional leads in the quest to understand what our ancestors ate. If you look at hominin tooth morphology over time, says paleoanthropologist and evolutionary biologist Peter Ungar of the University of Arkansas, you see that australopiths had big, flat teeth with thick enamel — traits that indicate they were specialized for crushing hard foods such as seeds. Homo, for its part, evolved smaller teeth with crests that were better suited to eating tough foods, including meat. Yet we obviously lack the long, sharp canine teeth that carnivores have for stabbing and tearing at prey and the sharp-edged carnassial teeth for shearing flesh.

"We're not pure carnivores, we never were," Ungar says. "Our teeth are not designed for meat eating." That doesn't mean we can't survive on animal tissue, he notes — cutting and cooking both make meat easier for us to consume — but "anybody who's chewed on beef jerky long enough knows that our teeth really aren't designed for that. Or, for that matter, raw steak."

The microscopic pits and scratches that foods leave on the teeth reinforce this message. Whereas Aus­tralopithecus microwear patterns reflect a narrow range of food types, early Homo shows a somewhat wider range. Later members of our genus show microwear texture patterns that indicate they ate even more kinds of foods. Although these lines of evidence are limited, Ungar says, they suggest Homo became a more versatile eater, capable of consuming a wider variety of foods than its predecessors. This versatility would have served our ancestors well as they spread into new environments with a greater diversity of food types on offer.

Proponents of animal-based diets are fond of pointing to the Hadza, a group of foragers in northern Tanzania, to make their case for going hard on meat. Saladino and Liver King name-check them regularly in their social media videos. "I can tell you very clearly that the Hadza don't give a shit about vegetables. They don't really eat vegetables," says Saladino, who once visited the Hadza on an excursion set up for tourists.

Anthropologists who have lived with the Hadza and studied their diet for years would disagree. Herman Pontzer of Duke University notes that for decades researchers have observed that plant foods make up at least 50% of the Hadza diet. The Hadza are not unique in this regard. Hunter-gatherers around the world get roughly half their calories from plant foods and half from animal foods on average. But that average obscures the real value of the hunting-and-gathering strategy, which is that it allows people to subsist on a wide variety of diets depending on what's available in their environment at a given time of year. Long-term studies of the Hadza show that some months they may get most of their calories from honey; other months they may eat mostly plant foods, including root vegetables. There are times they hardly eat any meat at all.

What made humans so triumphant wasn't that we swapped out plants for animals but that we added hunting to our repertoire. Hunting and gathering re­liably produces more calories a day than any other primate strategy, Pontzer says. The reason it works is that it's a mixed portfolio. "You have some people going after high-value, hard-to-get animals with a lot of pro­tein and fat, which is great," he says. "And you have peo­ple who are going after more dependable plant foods. It's the balance of those things that makes it so successful."

Hunting and gathering produces so many calories, in fact, that people can afford to share them with other group members, including children, whose brains take longer to develop than in other species and who need more time to learn how to fend for themselves. A strict plant eater can't do that, because although the number of calories one can get every day eating plants is very dependable, it might not be high enough to produce a surfeit of calories. A strict meat eater, on the other hand, will have long periods of famine between feasts that do not, on average, generate extra calories. But when we put those two things together, Pontzer observes, we generate a surplus. And that surplus, he surmises, is the variable that's made energetically expensive human things such as large brains and extended childhood possible.

What the fossil, archaeological and ethnographic evidence indicates, then, is that there is no one diet that nature prescribed for us. What our ancestors ate varied dramatically over time and space, driven in no small part by what was available to them as seasons changed, climate shifted, and populations spread into new ecosystems. Forged in that crucible of uncertainty, we evolved the ability to survive and thrive on an impressive diversity of foods. Hunter-gatherers around the world eat diets with wildly different proportions of plant and animal foods, and all of them appear to be healthy, protected from heart disease, diabetes, and other maladies that are common in industrial populations.

So what is a person looking to eat healthily supposed to do? "I think what it says is you should feel liberated to try a bunch of different diets and find one that works for you," Pontzer says. But "when somebody tells you that there's only one way to eat, they are wrong, and you can stop ­listening."

This article was first published at Scientific American. © ScientificAmerican.com. All rights reserved. Follow on TikTok and Instagram, X and Facebook.

On Tuesday (July 2), the Food and Drug Administration (FDA) announced that it will no longer allow brominated vegetable oil (BVO) in food or beverages due to safety concerns. 

But what is BVO, and what is it found in?

BVO is vegetable oil modified with bromine, a naturally occurring chemical element that's dark-reddish-brown and liquid at room temperature. Bromine is denser than water and sinks when added to it, and when combined with a vegetable oil, the element makes that oil denser than water. This effect makes BVO useful for emulsifying certain ingredients in water, ensuring that they're evenly distributed throughout the liquid and don't separate from it.

In the past 50 years, BVO has primarily been used to help stabilize citrus flavorings within sodas, sports drinks and energy drinks. That said, many U.S. beverage makers have already replaced the BVO in their products, and "today, few beverages in the U.S. contain BVO," according to the FDA. 

Related: PFAS 'forever chemicals' to officially be removed from food packaging, FDA says

Manufacturers started using BVO in food in the 1920s, prior to the FDA's establishment. The agency initially added the modified oil to its list of foods that are "generally recognized as safe" (GRAS). However, in the 1960s and 1970s, the oil's safety came into question as animal studies suggested that consuming the product might harm the heart. 

These early studies, however, fed the animals doses far beyond what humans would be exposed to, and later studies overturned the idea that BVO hurts the heart. But nonetheless, at the time, the FDA moved to limit the use of BVO. In the late 1960s, the oil lost its place on the GRAS list and was restricted to being used as an additive in very small amounts — 15 parts per million. 

In recent years, technologies improved and enabled the FDA to undertake better studies of the concentration of BVO in drinks and of the effects of the oil on lab animals. The animals were fed amounts of BVO that mimicked the real-life exposure a human might realistically experience.

A study published in 2022 showed that rats fed BVO accumulated high amounts of bromine in their blood and tissues, and breakdown products of the oil accumulated in various organs and in fat. The particularly concerning finding was that high doses led to enlargement of cells in the thyroid, a hormone-making gland in the throat. These effects on the thyroid can lead to conditions such as goiter, which is sometimes accompanied by the thyroid making too much or too little hormone. 

Following studies such as this, the FDA proposed that BVO should no longer be allowed in food. "Animal and human data, including new information from recent FDA-led studies on BVO, no longer provide a basis to conclude the use of BVO in food is safe," the agency stated.

The newly finalized rule will take effect Aug. 2, after which companies will have one year to reformulate, relabel and deplete their inventory of BVO-containing products. Many companies have already phased out BVO in their products, and some — such as Keurig Dr Pepper, the maker of Sun Drop soda — told news outlets last year that they were moving to drop the additive.   

"The removal of the only authorized use of BVO from the food supply was based on a thorough review of current science and research findings that raised safety concerns," Jim Jones, the FDA's deputy commissioner for human foods, said in a statement. 

"We will continue to monitor emerging evidence on the chemicals we have targeted for reassessment," he said, "and in cases such as this, where the science no longer supports continued authorized use, we will take action to protect public health."

When used in products, BVO must be listed as an ingredient on the label, either as "brominated vegetable oil" or as the specific oil that has been brominated, such as "brominated soybean oil."

You might hear bromine poisoning mentioned in relation to BVO. However, this type of poisoning most often happens when people inhale too much bromine — for example, when they're working in an environment with a lot of the element. Bromism, another bromine-related condition, is caused by chronic exposure to the element. This condition was more common when people used bromine as a sedative. There is only one known case in which a person seemingly got bromism from excessive soda consumption, so this is an extremely slim risk.

This article is for informational purposes only and is not meant to offer medical advice.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website! 

Americans seem to have quite a positive view of dietary supplements. According to a 2023 survey, 74% of U.S. adults take vitamins, prebiotics and the like.

The business of supplements is booming, and with all the hype around them, it's easy to forget what they actually are: substances that can powerfully affect the body and your health, yet aren't regulated like drugs are. They're regulated more like food.

Thanks in large part to a 1994 law, the Food and Drug Administration is essentially toothless when it comes to supplements. As the agency acknowledges: “FDA does not have the authority to approve dietary supplements before they are marketed. Companies can sell supplements without going through any sort of approval process, or even having to share safety evidence.”

As a research faculty member in graduate medical education, I'm responsible for teaching resident physicians how to understand and critically engage with health research. I also write about health, wellness and supplements for a broader audience. As a result, I spend a lot of time thinking about supplements.

It's important to consider why so many people believe supplements can help them lead a healthier life. While there are many reasons, how supplements are marketed is undeniably an important one. In my years following the industry, I've found that three mistaken assumptions appear over and over in supplement marketing.

1. The appeal to nature fallacy

The appeal to nature fallacy occurs when you assume that because something is "natural" it must be good. The word natural is used a lot in the marketing of supplements. In the context of health, it often feels right to want natural medicine, remedies, prevention techniques and so forth.

For example, if I say "vitamin C," what do you immediately think of? Probably oranges or citrus in general and flu prevention. But if I say "the flu shot," what immediately comes to mind? Probably doctor's offices, a little bit of pain and pharmaceutical companies. One of these is clinically proven to prevent flu infections and lessen the severity of illness. The other has been marketed as though it does those same things, but there's no clinical evidence to support this.

The supplement industry is awash with brand names that incorporate the word "nature," invoking the appeal to nature fallacy. Also, look at websites and advertisements that urge customers to forgo "artificial" products in favor of "pure" and "natural nutrition." Using the word artificial to describe other products and natural to describe a specific supplement is intended to make you feel like that product will be superior to the competition and that you need it to be healthy.

To be clear, "natural" does not equate to "better," but that's what the marketing wants you to think.

2. The belief that more of a good thing is always better

There's another assumption that piggybacks on the appeal to nature fallacy: If something is natural, it must be good, and more of it must also always be better. If a little vitamin C is good for us, then a lot of it must be great!

The truth is that our bodies tightly regulate levels of the vitamins and minerals we consume. If you don't have a deficiency, consuming more of a particular vitamin or mineral through a supplement won't necessarily lead to health benefits. That's why supplement skeptics sometimes say, "You're just paying for expensive pee" — since your body will excrete the excess.

For an example of the more-is-better myth, look at basically any vitamin C supplement. The packaging often prominently displays dosages that can reach 750 or 1,000 milligrams. But adults need only about 75 to 120 milligrams of vitamin C per day. Similarly, look at vitamin D supplements that can come in dosages of 5,000 IU, or international units — a fact also often prominently displayed on packaging. But adults should have no more than 4,000 IU daily. Again, it's easy to exceed what we need.

3. The action bias

Finally, the supplement industry likes to capitalize on the idea that doing something is better than doing nothing. This is the action bias. Taking action makes people feel like they have more control of a situation, which is especially powerful when it comes to health. "Even if I don't need the extra vitamin C," they might think, "I'll take it just to be sure. What’s the harm?"

The examples in the last section show that supplements often contain many times the recommended daily intake of a particular vitamin or mineral. This assumes that taking that much of any of those particular substances is safe.

It is possible to have too much of a good thing. Too much vitamin C can lead to diarrhea, nausea, stomach cramps and more. Too much vitamin D can lead to conditions including nausea, vomiting and kidney stones. Supplements can also interact with prescribed medications. For example, St. John's wort is famous for interacting with contraceptives, immunosuppressive drugs, statins and chemotherapy by exacerbating or dulling their effects. When it comes to supplements, taking them isn't necessarily better than not.

Be on the lookout for these marketing messages — they aren't necessarily correct or good for your health. And talk with your doctor before taking any supplements.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Intermittent fasting — a dieting strategy that limits when someone can eat each day — has been linked to a 91% higher risk of heart-related death in a large study. This risk was tied to eating in an eight-hour or shorter window in the 24-hour day, compared with a more typical 12- to 16-hour window.

The new, preliminary research was presented March 18 at the American Heart Association (AHA) EPI Lifestyle Scientific Sessions 2024. It looked at deaths from cardiovascular diseases in more than 20,000 U.S. adults, who were followed for an average of eight years.

Experts told Live Science that the study highlights a need to exercise caution around the use of intermittent fasting. However, one noted that, until all the data from the study is published, it's difficult to say whether the time window or types of food consumed are more relevant to a person's risk of death.

"It's quite possible to eat a really low-quality diet while time-restricted eating," Christopher Gardner, professor of medicine at Stanford University, told Live Science. It may also be that some participants with restricted eating windows were facing food insecurity and not eating well or enough, he added. "We don't know everything yet. I'll wait for more," he said of the new research.

Related: 9 heart disease risk factors, according to experts

'There is so much that isn't known'

Intermittent fasting involves eating only during a specific window of time each day, often between four and 12 hours out of 24. Previous research suggests that intermittent fasting improves metrics tied to cardiovascular health in the short term, over a few months, including measures of insulin resistance.

Of the 20,000 people in the new study, 414 reported eating in time windows of eight hours or less each day. Participants were not assigned diets to follow, but rather, their typical diets were assessed through two surveys, in which participants recalled everything they'd eaten in two 24-hour time frames.

The study uncovered a link between eight-hour eating windows and cardiovascular death, but due to its design, it cannot say whether this eating schedule caused the deaths — it shows only a correlation.

"We were surprised to find that compared to people whose eating duration was 12-16 hours … those who restricted their eating time within 8 hours per day had higher risk of cardiovascular death and did not live longer," lead study author Victor Wenze Zhong, professor of epidemiology and biostatistics at the Shanghai Jiao Tong University School of Medicine, told Live Science in an email.

Restricting eating to this short time window was tied to a higher cardiovascular death risk in the overall group and in people with either cancer or heart disease, who were singled out in separate analyses. In addition, participants with existing cardiovascular disease who ate during an eight- to 10-hour window also had a 66% higher risk of dying from heart disease or stroke, compared to those with longer eating windows.

Dr. Wendy Bennett, an associate professor of medicine at Johns Hopkins University School of Medicine, noted that this study suggests a need to scrutinize the "fad diet push that people should be doing time-restricted eating." Bennett and others published research in January 2023 that also raised doubts about the purported benefits of intermittent fasting, suggesting that it's not a successful weight-loss strategy in a six-year time window.

Zhong agreed that the new study calls for more caution regarding intermittent fasting, particularly for people with heart conditions or cancer. Overall, though, "it's too early to give a specific recommendation on [time-restricted eating] based on our study alone." He highlighted the need to explore exactly how eight-hour intermittent fasting might affect heart health and to assess additional populations around the world.

The study does have several limitations. For instance, participants provided dietary data through self-reporting, and some may have incorrectly recalled what they'd eaten. Only two diet surveys were used, so it's unknown whether these accurately represented people's long-term eating habits. The study also didn't consider the nutrient quality of participants' diets or reasons they practiced intermittent fasting.

"It looks tantalizing, but there is so much that isn't known," Gardner said, adding that there is a lot of interest in the study's full results.

Setting the new research aside, intermittent fasting can have other negative consequences, Cynthia Bulik, a psychiatry professor who studies eating disorders at the University of North Carolina School of Medicine, told Live Science in an email. For example, despite it being "hailed as the next great strategy for weight control," intermittent fasting can affect a person's familial and social relationships when their eating schedule doesn't align with that of their loved ones, she noted.

"In addition, for individuals who are genetically predisposed to some eating disorders, prolonged fasting periods could theoretically flip them into negative energy balance (expending more energy than they are consuming)," she said, "and trigger the onset of an eating disorder."

This article is for informational purposes only and is not meant to offer medical advice.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Manufacturers will no longer use harmful "forever chemicals" in food packaging products in the U.S., according to the U.S. Food and Drug Administration (FDA).

In a statement released Feb. 28, the agency declared that grease-proofing materials that contain per- and polyfluoroalkyl substances (PFAS) will not be used in new food packaging sold in the U.S. These include PFAS used in fast-food wrappers, microwave popcorn bags, takeout boxes and pet food bags. The FDA's announcement marks the completion of a voluntary phase-out of the materials by U.S. food packaging manufacturers. 

This action will eliminate the "major source of dietary exposure to PFAS," Jim Jones, deputy commissioner for human foods at the FDA, said in an associated statement. Companies told the FDA that it could take up to 18 months to completely exhaust the market supply of these products following their final date of sale. However, most of the affected manufacturers phased out the products faster than they initially predicted, the agency noted. 

"This FDA-led effort represents a positive step forward as we continue to reevaluate chemicals authorized for use with, and in, food," Jones said. "It underscores an important milestone in the protection of U.S. consumers from potentially harmful food-contact chemicals."

Related: Scientists find a simple way to destroy 'forever chemicals' — by beheading them

PFAS are a diverse group of synthetic chemicals that resist water, oil, heat and stains, which is why they've historically been used in a wide variety of products, including food packaging, household cleaners and nonstick cookware. PFAS are super durable chemicals that can take years to break down, hence why they're often called "forever chemicals." 

Once discarded, PFAS can leak into the environment as they slowly break down, accumulating in soil, rivers and lakes, for instance. The chemicals can also enter the body when people consume water or food that's been exposed to the chemicals during production or packaging, or when they breathe in dust tainted with PFAS. They can accumulate in a person's blood and in breast milk. 

Numerous studies have demonstrated the potential health effects of being exposed to different PFAS. For example, the chemincals have linked to disruptions in the immune system, weight gain and decreased fertility in a mixture of animal and human studies, as well as cell-based research. 

The FDA's February announcement is several years in the making. As an initial step in 2020, the agency announced that it was working with manufacturers to voluntarily phase out the use of certain PFAS in food packaging, such as grease-proofing agents on paper and paperboard products. The goal was to phase out these products within three years. 

The FDA's new announcement marks a "huge win for the public," Graham Peaslee, a professor of physics at the University of Notre Dame who studies PFAS, told The Washington Post.   

"Nobody reads the wrapper of their hamburger to see if it has PFAS or not," Peaslee told the news outlet. "It's going to be a huge win that we don't have to worry about where it ends up," he said. 

Removing PFAS from food packaging is a "great step in the right direction," Dr. Sheela Sathyanarayana, a professor of pediatrics at the University of Washington School of Medicine in Seattle, told CBS News. 

However, although food packaging is the main way people are exposed to PFAS through their diets, there are also "many sources of PFAS in our environment," Sathyanarayana noted. These include drinking water and meat and dairy products, she said, since livestock and poultry can be exposed to PFAS in a variety of ways during production. 

Again, it could take 18 months for leftover stocks of PFAS-containing food packaging to be removed from the market. In the meantime, "the FDA will continue to conduct research and update our evaluations using the most up-to-date science to ensure that our risk determinations continue to be accurate," Jones said. 

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website! 

Drinking lots of artificially sweetened beverages, such as diet sodas, comes with a 20% higher risk of an irregular heartbeat, a new study finds. 

The research also revealed that consuming similar amounts of sugar-sweetened drinks was linked to a 10% bump in risk. Adults who reported drinking at least 2 liters, or roughly 67 ounces, of sweetened drinks a week saw these jumps in risk, compared to people who drank none. 

However, the study found only an association between these beverages and irregular heartbeats — it can't say that sugar or artificial sweeteners actually cause the heart condition.

Related: Is Diet Coke bad for you? 

In the study, published Tuesday (March 5) in the journal Circulation: Arrhythmia and Electrophysiology, researchers reviewed self-reported diet data from about 202,000 people in the U.K. Biobank, a repository of genetic and health data from half a million U.K.-based participants. 

Over an average of nearly 10 years for each participant, the researchers checked to see who developed atrial fibrillation, or AFib for short. 

This type of arrhythmia occurs when the upper chambers of the heart beat irregularly. AFib can cause blood clots and heart failure, and it's the leading cause of stroke, CNN reported.  

People who consumed the equivalent of one 12-ounce artificially sweetened drink a day saw the greatest risk of AFib, compared to those who drank no sweetened beverages. These drinks were sweetened with ingredients such as sucralose, aspartame, saccharin and acesulfame.

However, adults who drank 1 liter (34 ounces) or less of pure juice with no added sugars, such as 100% orange or vegetable juice, had an 8% lower risk of the condition than those who drank artificially sweetened beverages, according to an American Heart Association (AHA) statement.    

"This is the first study to report an association between no- and low-calorie sweeteners and also sugar-sweetened beverages and increased risk of atrial fibrillation," Penny Kris-Etherton, a member of the AHA's nutrition committee who was not involved in the study, said in the statement. 

"While there is robust evidence about the adverse effects of sugar-sweetened beverages and cardiovascular disease risk, there is less evidence about adverse health consequences of artificial sweeteners," she said.

Some evidence has linked beverages made with sugar substitutes to an increased risk of heart attack and stroke. 

In addition, in 2023, an arm of the World Health Organization (WHO) declared aspartame a "possible carcinogen," although the organization's process of identifying possible cancer-causing agents is fraught with problems. But the U.S. Food and Drug Administration (FDA) disagrees with the WHO's stance, stating that it hasn't found any link between aspartame and cancer. 

Because the new study only observed people's beverage consumption habits, it could not demonstrate that artificial sweeteners or sugar actually cause AFib. For instance, it's possible that some underlying factors predispose people to both drink more diet soda and have the heart condition.

"Although the mechanisms linking sweetened beverages and atrial fibrillation risk are still unclear, there are several possible explanations, including insulin resistance and the body's response to different sweeteners," lead study author Dr. Ningjian Wang, a researcher at the Shanghai Ninth People's Hospital and Shanghai Jiao Tong University School of Medicine in China, said in the AHA statement.

"We still need more research on these beverages to confirm these findings and to fully understand all the health consequences on heart disease and other health conditions," Kris-Etherton added. "In the meantime, water is the best choice, and, based on this study, no- and low-calorie sweetened beverages should be limited or avoided."

This article is for informational purposes only and is not meant to offer medical advice.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Antioxidants are nature's weapon against harmful molecules called "free radicals," which are continuously created by the body as cells do their jobs. These unstable molecules can damage our cells and cause diseases such as cancer as we age.

Some antioxidants are made by the body, while others — like beta-carotene from carrots, lycopene from tomatoes and polyphenols from grapes — come from a person's diet. All are thought to prevent and limit the cell damage, or "oxidative stress," caused by free radicals.

But given all their benefits, is it possible to have too many antioxidants?

Research shows that people whose diets are full of antioxidant-rich fruits, vegetables and legumes tend to have a lower risk of cardiovascular disease, cancer and early death from any cause. So it's easy to think that upping your antioxidant intake — by taking supplements, for instance — would be beneficial. But compared with food, supplements make it easier to exceed the recommended doses of antioxidants, which can actually be harmful.

Related: Does vitamin C help with colds?

Side effects of high antioxidant doses range from mild to very serious. On the milder end, high amounts of beta-carotene are known to turn the skin yellow or orange, which is visually striking but not harmful, per se. Excessive vitamin C intake can lead to digestive issues, like diarrhea, nausea and abdominal cramps.

More seriously, high doses of beta-carotene may increase the risk of lung cancer and cardiovascular disease in individuals already at high risk for these diseases, such as current and former smokers and people who have been exposed to asbestos. There's also evidence from studies of animals and human tissue suggesting that antioxidants can encourage the growth and spread of some cancers.

In addition, high-dose vitamin E supplements have been shown to interact with certain medicines, such as aspirin, warfarin, tamoxifen and cyclosporine A. They've also been tied to an increased risk of early death in people with chronic disease.

These studies suggest that, yes, having excessive amounts of antioxidants can be bad for you — but why? One reason is that low amounts of free radicals can actually be helpful. 

"There is lots of evidence indicating that free radicals have beneficial roles in physiological processes," Ismail Laher, a professor of pharmacology at the University of British Columbia, told Live Science in an email. At low concentrations, free radicals help cells grow and are part of the body's defense mechanism against disease. They are also involved in the metabolism, or breakdown, of drugs and participate in cell-to-cell communication.

However, "If too many antioxidants are consumed, these normal and essential processes can be disrupted, resulting in undesirable effects," James Kehrer, a professor emeritus and dean at the University of Alberta Faculty of Pharmacy and Pharmaceutical Sciences and an adjunct professor at the University of New Mexico College of Pharmacy, said in an email to Live Science.

How can we make sure not to overdose on antioxidants? Skip the supplements, and stick to a healthy diet, Kehrer recommends.

"When someone eats a balanced diet that includes sufficient fruits and vegetables, the right amount of antioxidants will be consumed," Kehrer said. "Dietary supplements are rarely, if ever, needed, except in the long-term absence of an appropriate diet, or in some types of diseases." For instance, you may be recommended supplements if you have ataxia with isolated vitamin E deficiency (AVED), a rare inherited neurodegenerative disorder.

Exercise is also important, Laher noted. The body is capable of generating its own antioxidants, and exercise increases this built-in antioxidant production in the muscles, heart and liver.

If you are considering an antioxidant supplement, discuss it with a health care professional. It's essential to be aware of the supplement's doses and how they align with your daily dietary intake, because overconsumption may lead to toxicity. It's also important to know if a supplement could interact with a medication you take.

When it comes to antioxidants, it's important to consider a concept called "hormesis," which is when a low dose of a substance has a beneficial effect but a high dose has a toxic effect. Or, as Kehrer put it, "If a little is good, more is NOT better."

This article is for informational purposes only and is not meant to offer medical advice.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Maintaining a balanced diet can be hard enough on Earth, but it's even more difficult in space — especially when you're talking about long-haul missions. Although space-based agriculture has made strides in recent years, growing fresh crops in space is no easy feat, and each bit of food or water stored in a spacecraft adds mass, thus weighing down the vessel during its journey out of orbit.

Scientists recently studied possible nutrient-dense meals fit for long-term space travel, such as potential Mars missions, that both satisfy astronauts' nutritional needs and taste better than existing alternatives. They tested 10 dishes to see which would be the optimal meal for male astronauts; they plan to specifically study meals for female astronauts in the future. The best meal would help space travelers get the calories and variety of nutrients they need during their odysseys and use crops that could be grown in space with minimal water.

Ultimately, the best space meal turned out to be a hearty kale salad, according to their study, published Dec. 13 in the journal ACS Food Science & Technology.

"These assessments are essential steps toward feasibility in long-term human space missions, for example, to Mars," the authors wrote.

Space travelers have different nutritional requirements than people on Earth do. That's because astronauts face unique stressors, including the vibration, noise, weightlessness, cosmic radiation and drastic temperature changes inherent to spaceflight. Research suggests that a male astronaut needs to consume around 2.6 pounds (1.2 kilograms) of food per day to maintain their body weight and energy levels. That diet should include more than double the carbohydrates and proteins than a typical person on Earth would require.

Related: NASA reveals first image of 'space tomatoes' that went missing on the ISS for 8 months, and they're gross

With this in mind, the team assessed a variety of nutrient-dense ingredients using a statistical model, which also measured the foods' capability of being grown in space or stored for a long time in a spacecraft. This model yielded 10 "space dishes"; four were vegetarian, and six were made with plants and meat.

Compared with plants, meat options typically provide a higher concentration of certain key nutrients, such as protein and vitamin B12. However, the storage of animal products "requires a large space for long-term space missions," making them tough ingredients to regularly include in an astronaut's diet, the study's authors wrote. (In addition, there aren't yet efficient methods for growing lab-grown meat, although the field is advancing.)

The team couldn't include baked goods like bread, because crumbs can float around in microgravity and damage equipment in the spacecraft.

Crops, on the other hand, could be grown during space travel. Considering all of these factors, the researchers' models determined that the optimal dish to meet astronauts' nutritional needs while being feasible for space travel is a vegetarian salad made with soybeans, poppy seeds, barley, kale, peanuts, sweet potato and sunflower seeds — but notably, no salad dressing.

"I think their choice was very well done," Kathleen Carter, a nutritional researcher at Central State University in Ohio who was not involved in the study, told Live Science. "I think that as we start extending our time in space, we're going to have to go to more plant-based. We're going to have to be able to grow our own resources."

Beyond nutritional value, the researchers studied another factor in the ideal astronaut meal: taste. They fed four volunteers the optimized space salad and recorded their feedback on its palatability. Overall, the results were positive, with one volunteer saying they "enjoyed the sweet taste of the potatoes and freshness crunch."

However, the researchers flagged some key limitations with this meal option.

While some plants, including Chinese cabbage and tomatoes, have been cultivated in space in recent decades, there still isn't a reliable and efficient cultivation system to maximize output in this environment, they noted in the study. Additionally, the optimized salad is still missing some of the vitamins and minerals an astronaut would need each day, though these could be provided through supplements, the authors wrote.

Future studies should also consider the cultural and individual dietary requirements of each astronaut, Carter said. Their space menu would need to accomodate any allergies, personal preferences or dietary restrictions, she added.

"Different cultures are going to want different types of foods," Carter said. "Making sure that food looks good, that it tastes good [and] that it's something that they really want to eat, in addition to being very nutrient dense, is going to be very important."

The researchers plan to use their models to design meals for female astronauts and to incorporate more crops into its algorithm, according to a statement.

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A violent bout of "drunk hiccups" isn't the worst thing that can happen to you after having one too many beers, but it can certainly be irritating.

Drunk hiccups are common enough that, in classic cartoons, a character hiccuping after downing a swig of alcohol is understood as meaning they're intoxicated — but can drinking alcohol really cause hiccups? Or are there other factors at play?

In truth, we know surprisingly little about drunk hiccups. Clinical case reports have indeed suggested a connection between alcohol consumption and hiccups. But Dr. George Koob, director of the National Institute on Alcohol Abuse and Alcoholism, told Live Science he's not aware of any studies that specifically investigate the mechanism behind this phenomenon.

However, there are several theories as to how alcohol might trigger hiccups. One explanation is that ethanol — the type of alcohol in beverages such as beer, wine and spirits — may cause hiccups by disrupting the normal flow of nerve signals in the body.

Related: What does alcohol do to the body?

The characteristic "hic" sound is caused by the sudden closing of the vocal cords due to repeated spasms of the diaphragm, the dome-shaped muscle that contracts and relaxes to pull air into the lungs and then push it back out. As with any other muscle, the diaphragm moves in response to electrical impulses generated by the nervous system.

"Existing papers on the effects of alcohol on the respiratory system support the hypothesis that alcohol impairs the normal functioning of muscles in the upper airway and diaphragm by affecting the communications between nerve cells and muscle fibers, and this can lead to hiccups," Koob told Live Science in an email.

"For example, in one study, the researchers looked at how alcohol affects muscles in the rat diaphragm, and found that ethanol interferes with the transmission of signals between nerves and muscles in rat nerve-diaphragm tissue samples," Koob noted.

In addition, drunk hiccups may be linked to gastroesophageal reflux disease (GERD), a condition in which stomach contents flood into the esophagus. Alcohol relaxes the ring-shaped muscle that separates the esophagus from the stomach, known as the lower esophageal sphincter, and the dysfunction of this valve is a key feature in GERD.

"And while we are not sure whether there is a direct link between alcohol per se and hiccups, we do know that hiccups are more frequent in people with this disorder," Koob said.

Studies suggest that up to 10% of patients with GERD have recurring bouts of hiccups, according to the medical resource StatPearls. Moreover, the risk of developing the condition rises proportionally to alcohol consumption, according to a 2019 meta-analysis published in the journal Alcohol and Alcoholism. However, more research is needed to understand the link between hiccups, alcohol use and GERD.

"It is also important to note, that in addition to GERD, hiccups are more frequent in people with neuropathies [nerve damage], liver diseases, and pancreatic diseases," Koob said. "And alcohol is a leading cause of all of these conditions. So it's possible that improvement of medical conditions caused by problematic alcohol use may also help in resolving the hiccups."

However, in people who don't typically drink much alcohol, an occasional bout of drunk hiccups is likely nothing to be worried about, although the spasms can be a pain to get rid of.

This article is for informational purposes only and is not meant to offer medical advice.

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You're at a dinner party and have just locked eyes with the cheese board. As the first tantalizing bite of Gorgonzola passes your lips, a question might cross your mind: Why is it okay to eat this moldy food, when a lot of mold makes us sick?

Molds are thread-like fungi that grow on plants and animal products. There are millions of species of mold: some are dangerous to humans, but most are harmless. That's the case for the mold in cheeses.

There are two main varieties of moldy cheese: the blue-mold cheeses, such as Stilton, Roquefort and Gorgonzola, and the white-mold cheeses, including brie or Camembert. 

Blue cheeses contain a species of mold called Penicillium roqueforti. During production, the mold is mixed in with the clumps of coagulated milk, called curds, that are used to make cheese. The mold then develops inside the cheese and turns blue, providing blue cheese its characteristic, sharp, strong flavor profile, Heather Hallen-Adams, a food microbiologist at the University of Nebraska-Lincoln, told Live Science. 

Related: Scientists identify the microbes that make buffalo mozzarella so yummy 

White-mold cheeses, on the other hand, contain a different species of mold called Penicillium camemberti. In this case, the cheese is made and then the mold is introduced on the outside of the final product, which is what you notice as the hard outer layer or rind of Camembert, for instance. 

"Both molds are doing what all fungi do," Hallen-Adams said. When we eat food, our guts secrete enzymes that allow us to digest the food, and fungi do something similar. 

"Fungi secrete digestive enzymes into their environment, break things down into simple fatty acids, amino acids [the building blocks of proteins] and carbohydrates and then absorb them," Hallen-Adams said. 

In the fungi in cheese, these enzymes are usually proteases, which break down proteins, and lipases, which digest fats. A wheel of Camembert, for example, has a thin, flat, large surface area, which allows these digestive enzymes to get all the way into the middle of the cheese, giving it its creamy texture, Hallen-Adams said. 

"With the blue cheeses where the fungus is throughout the cheese, that doesn't matter as much and due to differences in the fungus, it's more of a crumbly texture than a creamy texture," Hallen-Adams said. 

Humans figured out that it was safe to eat these Penicillium molds largely through trial and error, Hallen-Adams said. Legend has it that blue cheeses were discovered hundreds of years ago when a shepherd forgot about some cheese that he'd left in a cave for a few months. When he came back, he noticed that it contained mold that had been growing in the cave — what we now know to be P. roqueforti.

The discovery of the white-mold cheese Camembert was a little bit more deliberate, but still involved a sense of figuring out that, "okay, we can eat this," she said.  

What about mold on other types of cheese? 

"I always tell people, 'Roquefort is meant to be a blue cheese, cheddar generally isn't,'" Hallen-Adams said. "If you have blue mold on your cheddar, and that will happen sometimes, that's probably a Penicillium and you probably don't want to eat that as it could well be a different species," which could make you sick, she said. 

Other species of mold, such as Aspergillus flavus, can also grow on cheeses and produce toxins that are harmful to humans. Pathogenic species of bacteria — for example, Staphylococcus aureus or Escherichia coli — can also grow on cheese alongside mold. 

However, you can safely remove suspect mold without having to throw the whole lump of cheese in the trash. "Generally, you're safe cutting back maybe half a centimeter [0.2 inches] or a centimeter [0.4 inches] behind the growing front of the mold and the rest of your cheese is safe and fine," Hallen-Adams said.

It should be noted, however, that harmless bacteria and yeast also play a role in the cheese production process.

"Cheese is actually a pretty complex ecosystem. You've got the molds that you put in, some molds you don't, some yeasts [such as Debaryomyces hansenii or Geotrichum candidum], and almost any cheese has lactic acid bacteria that are the main culture organisms to make the cheese to begin with," Hallens-Adam said. 

"It's a whole microbial party there," she said. 

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If you enjoy a shiraz or Chianti from time to time, you may be familiar with the dreaded "red wine headache." That pain may stem from a compound called quercetin, which disrupts the body's ability to break down alcohol, scientists have discovered. 

Quercetin is an antioxidant found in fruit and vegetables, including grape skins, and some people take it as a supplement for its purported health benefits. However, at least in the lab, scientists discovered that it inhibits an enzyme called aldehyde dehydrogenase (ALDH) that's key for metabolizing alcohol in the liver. 

Alcohol in the body first gets intercepted by alcohol dehydrogenase (ADH), which breaks it down into a toxic compound called acetaldehyde. ALDH then quickly diffuses that toxin, transforming it into something that can be broken down into water and carbon dioxide. But if what happens in lab dishes also occurs in the body, quercetin may cause acetaldehyde to accumulate. High levels of the toxin in the body can cause flushing, headaches and nausea. 

The findings, published Monday (Nov. 20) in the journal Scientific Reports, have yet to be confirmed in humans. But as red wine contains much more quercetin than other alcoholic drinks, the authors say the compound is likely to be the cause of the headaches. 

Related: What happens to your body when you stop drinking alcohol?

"We think we are finally on the right track toward explaining this millennia-old mystery," co-senior study author Dr. Morris Levin, a professor of neurology at the University of California, San Francisco, said in a statement. 

Scientists have previously proposed many theories to explain the headache that often arrives half an hour after that first sip of merlot, such as preservatives in wine called sulphites being responsible or the inflammatory chemical histamine. But other studies have refuted these ideas. For instance, different levels of histamine in pinot noir had no effect on people's wine tolerance in one study, The New York Times reported. 

Now, the authors of the new study think they may have found the answer. "When it [quercetin] gets in your bloodstream, your body converts it to a different form called quercetin glucuronide," study co-author Andrew Waterhouse, a wine chemist at the University of California, Davis, said in the statement. "In that form, it blocks the metabolism of alcohol," he said. 

The authors ran specific chemical tests in the lab using samples of quercetin and related compounds, as well as a purified ALDH enzyme. After discovering that quercetin glucuronide inhibits ALDH, the authors estimated that one standard glass of red wine — around 5 ounces (147 milliliters) — would theoretically result in levels of quercetin glucuronide in the blood that could inhibit ALDH by up to 40%. These rough estimates are based on previous studies that examined quercetin levels in people's blood after drinking wine which were factored into the current study's predictions of ALDH inhibition.

The authors plan to test their hypothesis in a small human study where they'll compare people's reactions to red wines with different amounts of quercetin, to see if people are more or less likely to develop headaches. 

If proven in humans, the findings could provide opportunities to give customers more choice in the amount of quercetin that ends up in their glass. 

Quercetin is produced when grapes are exposed to sunlight, so varieties that are grown in different regions will contain different amounts of the compound. How much the wine touches grape skins during fermentation, as well as how it is clarified and aged, can also influence quercetin levels. To make red wine, wine makers leave the grape skins in during fermentation, whereas they remove the skins when making white wine; that's why red wine contains more quercetin than white.  

"It will be potentially very helpful for people who drink red wine to be able to choose wines less likely to cause headaches," Levin told The Guardian. "Also, winemakers may use our findings to reduce quercetin in their wines," he said. 

This article is for informational purposes only and is not meant to offer medical advice.

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Humans have been around for about 2.5 million years. For at least 2.4 million years, people have been eating animals. This fact is evidenced by cut traces on fossil animal bones, surviving stone tools and analyses of our ancestors' teeth. While Homo habilisand Homo rudolfensis probably only ate a lizard here and there or the meaty remains left behind by other predators, Homo erectus was a hunter. Today, by some counts, the average American eats around 7,000 animals in a lifetime — including 4,500 fish, 2,400 chickens, 80 turkeys, 30 sheep, 27 pigs and 11 cows. This number not only sounds absurdly high; it raises a question: Is this really necessary?

According to one well-known theory meat consumption made us human. As early as the mid-1950s, paleoanthropologist Raymond Dart coined the idea that our early ancestors hunted animals to survive on the barren African savannah. Finally, in the 1990s, Leslie Aiello and Peter Wheeler posed the expensive-tissue hypothesis, according to which other tissues had to regress as the human brain evolved. They wanted to answer the question of where early hominins got the energy for their ever-growing organ of thought. While the brain volume of Homo rudolfensis was still about 750 cubic centimeters, Homo erectus already had up to 1,250 cubic centimeters. Today, Homo sapiens even has a brain volume of 1,100 to 1,800 cubic centimeters.

The human brain is an enormously expensive organ. Although it accounts for only a few percent of total body mass, it consumes a good fifth of total energy. Compared to roots, leaves and many other plant parts, meat (especially offal such as liver, heart or tongue) has a fairly high nutrient density with many proteins and, above all, fats. If it is also chopped up, it saves a lot of chewing, which means that the energy-rich food can be ingested with little energy consumption. Any surplus can then go to the development and operation of the brain — or so the argument goes.

Many people today justify their excessive meat consumption to themselves and others with these arguments. Modern man is a born meat eater, they reason, as a glance at human history shows. What's more, the mastery of fire, the development of language, the origin of the division of labor, the beginning of social hierarchies and even the emergence of culture could be related to hunting and eating meat. Accordingly, the consumption of meat is a natural need of humankind whereas vegetarianism is unnatural and possibly even harmful to health. But experts from such diverse fields as paleoanthropology and nutrition are questioning these ideas.

We are constantly evolving

Human evolution is not locked but instead constantly developing. What was true for our ancestors is not necessarily still true today. For example, food's availability, composition and preparation have changed enormously since early humans acquired a taste for meat. We no longer have to spend half a day stalking an animal. Modern breeding methods have significantly increased the nutrient content in plant foods. And over time, we have learned to cook our food so that it is easier to digest and nutrients are more accessible.

Today, meat is no longer a luxury product. On the contrary, a cutlet is sometimes cheaper than a sack of potatoes. However, its production consumes many times more resources. Some 77% of the world's arable land is used for meat and milk production, even though animal products provide only about 18% of the world's calorie needs. Even if there were an evolutionary link between meat consumption and becoming human, we should be able to emancipate ourselves from it today.

Moreover, numerous paleoanthropological studies cast doubt on, or refute, the "meat made us human" theory. For example, a team led by Ana Navarrete of the University of Zurich found no further evidence in the animal kingdom for the expensive-tissue hypothesis in extensive analyses. To be sure, "this highly intuitive idea has gained wide acceptance in paleoanthropology and many other fields, and is fueling public discussions about the optimal human diet," the group wrote in the journal Nature in 2011. However: "Contrary to the predictions of the expensive-tissue hypothesis, we found no negative correlations between the relative size of the brain and the digestive tract, other expensive organs or their combined sum among mammals or within [nonhuman] primates." It would be most surprising if the principle applied solely to human evolution.

In a 2022 study, a research group led by paleoanthropologists W. Andrew Barr of George Washington University and Briana Pobiner of the Smithsonian National Museum of Natural History took another systematic look at the purported archaeological evidence for the "meat made us human" theory. The scientists compiled data from 59 sites from nine major research areas in East Africa, ranging in age from 2.6 to 1.2 million years old. Then the team put all previous bone finds into chronological perspective. Archaeological evidence of meat consumption does increase sharply when looking at specimens linked to the emergence of the Homo erectusspecies, the researchers reported in the journal PNAS. However, they found, this trend reflects the scientific focus on that period of evolutionary development; that is, there is simply more material collected from sites linked to early Homo erectus. As a result, the picture is distorted and the connection between eating meat and the evolution of the genus Homo is falsely underscored, they said. "Our study undermines the idea that eating large quantities of meat drove evolutionary changes in our early ancestors," Barr said in a press release.

Harvard primatologist Richard Wrangham goes even further. He argues that the greatest revolution in human nutrition occurred not when we started eating meat, but when we learned to cook. By pounding and heating foods, he says, they are "predigested" so that our bodies have to expend less energy breaking them down. Cooked food would thus allow humans to absorb more energy than raw food, ultimately providing more fuel for the brain in less time.

Wrangham tested his theory by offering raw and cooked food to rats and mice. The result: mice raised on cooked food gained 15% to 40%t more weight than mice fed only raw food. Whether cooked food was really the key driver behind human evolution, however, is difficult to prove in detail. Fireplaces leave much more perishable traces than stone tools and bones. They are therefore more difficult to trace and date. It is possible that humans began cooking their food until it was soft much earlier than we think.

Victims of our own success

The flip side of Wrangham's hypothesis is that we now have become so good at processing food that — for the first time in human evolution — many people eat more calories than they can burn in a day. "After millennia of food scarcity, we've been living in food abundance for almost 70 years. Our bodies can't handle that," says Hans Hauner, professor of nutritional medicine at the Technical University of Munich. "We see today that high meat consumption shortens the lives of many people and can contribute to numerous diseases such as diabetes, cancer and cardiovascular ailments." It would therefore do us good to significantly reduce our meat consumption.

In the course of human history, meat never displaced other dietary components; it supplemented them. It's a bit like equipping a city with a subway system: it doesn't replace anything; it just increases efficiency. "In the course of their evolution, humans have always consumed what was available to them," Hauner explains. Thus, it is not meat consumption that makes us human, but rather our enormous metabolic adaptability. "Humans, unlike many other animals, are able to extract from different food sources in their environment what ensures their survival." Our muscles can burn carbohydrates, but likewise metabolize fatty acids. In the same way, our brains can also switch from a sugar-based diet, at least in part, to a ketogenic diet.

Lutz Kindler of the Leibniz Center for Archaeology agrees from a paleoanthropological perspective. "Animals, unlike plants, are independent of the season and available even in the most inhospitable regions of this earth," he says. "So when humans started moving northward from Africa, there were many advantages to accessing additional, non-plant food sources." There were also the social aspects of hunting and eating meat. "People had to organize themselves to be able to kill and cut up large animals despite their physical inferiority." That probably brought them together. Meat and its exploitation, he said, therefore had an influence on our behavioral evolution more than anything else. "From my point of view, however, meat was and is not necessarily nutritionally relevant. Proteins alone do not have a particularly high calorific value," Kindler adds.

The question remains whether we still need animal proteins and the micronutrients contained in meat today. As nutritionist Hauner points out, "Today there are quite competitive sportsmen who nourish themselves through a purely vegetarian or vegan diet. So you can also optimally supply your muscles and brain with vegetable proteins."

While studies worldwide have shown the value of a balanced, healthy diet with some amount of meat, dairy and other animal products, he says, "the only one that is really challenging is a vegan lifestyle. And even there, in this day and age, there are numerous ways to replace the missing substances."

Paleoanthropologist Kindler, meanwhile, believes that tastes and food sources are "handed down and more of a social issue than one of physiological evolution or instinct." So if people were to return more to the diet of their ancestors, eat more local fruits and vegetables, and eat significantly less meat, it would be good news for their health — and for our planet. After all, humans' enormous adaptability and insatiable appetite for meat today is one thing above all: an ecological disaster.

This article originally appeared in Spektrum der Wissenschaft and was reproduced with permission.

This article was first published at Scientific American. © ScientificAmerican.com. All rights reserved. Follow on TikTok and Instagram, X and Facebook.

After you eat beets, you may get a shock when visiting the restroom: Your poop looks slightly pink, or sometimes dark, berry red.

This rather unnerving experience may make you wonder, "why do beets turn your poop red?"

The answer lies in betanin, the reddish-purple pigment that gives red and purple beets their vibrant color, Whitney Linsenmeyer, an assistant professor of nutrition and dietetics at Saint Louis University in Missouri and a spokesperson for the Academy of Nutrition and Dietetics, told Live Science by email. The same pigment is not found in golden beets, which instead contain yellowish pigments called betaxanthins.

Betanin is not only a pigment but also a strong antioxidant, meaning it can neutralize reactive molecules called "free radicals" in the body. By stabilizing free radicals, "it may help prevent damage to DNA and other cells and is also considered to have anti-inflammatory properties," Linsenmeyer said.

Related: Nine benefits of antioxidants: From disease prevention to healthy aging

However, betanin has a low bioavailability, meaning little metabolized betanin enters the bloodstream, so the body can't make full use of the compound. The pigment is highly resistant to digestive processes, and only a fraction of the betanin we consume can get absorbed by the cells in the gut, Linsenmeyer said. Lab-dish and animal studies suggest that roughly half of the ingested betanin gets broken down, mainly in the intestines, according to a 2021 review published in the journal Molecules.

Betanin that is not broken down by the body passes through the digestive tract largely intact. That means it may end up excreted with poop, turning it red or pink as a result. "This is a normal reaction observed in about 1 in 10 people," Linsenmeyer said.

This widely cited statistic likely comes from a 1963 study, which suggested that 10% to 14% of people experience "beeturia," a phenomenon where beets turn your urine red or pink. Beeturia happens when unmetabolized betanin passes through the kidneys and into urine, but it's often accompanied by betanin turning a person's poop reddish, as well. So the two phenomena are closely linked.

"It is considered a benign condition that may persist for a few hours after the meal," Linsenmeyer said of beeturia.

Some studies initially suggested that a person's likelihood of experiencing beeturia might be linked to genetic factors or to iron deficiency, but more recent studies have concluded that the effect is more likely caused by the body's limited ability to metabolize betanin, according to the 2021 review.

"If you notice discolored urine several days later, however, this is not likely caused by eating beets and warrants a call to your doctor," Linsenmeyer said. Urine with a persistent red or pink color can indicate presence of blood, and according to Penn Medicine, bloody urine is a common sign of structural abnormalities or diseases within the urinary tract.

The exact time it takes for beets to turn your poop red can depend on how long it typically takes you to digest food. If you're concerned about your stool turning a reddish color, doctors can test a sample to rule out the presence of blood, and along with that exam, they'll likely ask if you've recently eaten something that might have turned your poop pink, according to the National Library of Medicine's MedlinePlus.

This article is for informational purposes only and is not meant to offer medical advice.

When you're tucking into one of your favorite foods — perhaps a steaming bowl of ramen or spectacularly cheesy slice of pizza — you're probably not thinking about the journey each morsel is about to take through your digestive system.

Of course, what started out as a delectable meal will eventually end up at the bottom of a toilet bowl. But how long does it take to digest food, exactly?

The answer to this question is more complicated than you might think. Different types of foods are broken down and absorbed by the body at different rates, meaning some parts of the meal may be entering the large intestine when other parts are still in the stomach. It's also common for healthy people to digest food at slightly different rates, according to Colorado State University.

Scientists have conducted studies assessing "gut transit time," or how long it takes a substance to move through the whole digestive tract, using ingestible capsules that can be tracked throughout their journey. These studies suggest that it can take anywhere from 0.4 to 15.3 hours for food to leave the stomach, and from 3.3 to 7 hours for it to pass through the entire small intestine. The leftover, indigestible parts of food then enter the large intestine, where they may remain for approximately 15.9 to 28.9 hours, according to a review published in the Journal of Clinical Medicine in 2023.

Related: Why can't humans digest corn?

Foods rich in dietary fiber, protein, complex carbohydrates and fats tend to take longer to digest than foods low in these nutrients, Dr. Nina Nandy, a gastroenterologist based in Texas and American Gastroenterological Association spokesperson, told Live Science by email.

"Fiber adds bulk to the diet, which slows down the movement of food through the digestive tract," she said. "Heavily processed foods tend to be digested more quickly as they lack this nutrient." Meanwhile, while they can process less-nutrient-dense foods fairly quickly, the stomach and small intestine take more time to break down foods rich in proteins and fats into nutrients that can be used by the body.

Similarly, complex carbohydrates — like those found in whole grains, legumes and starchy vegetables — take longer to digest than simple sugars. That's because complex carbs are made of long, complex chains of three or more types of sugar molecules, while simple sugars contain only one or two sugars. 

"The body has to break [complex carbs] down into simple sugars before absorption can happen," Nandy said. (Fiber is a complex carb that can't be broken down at all.)

Lifestyle factors also affect gut transit time. Chewing thoroughly and staying hydrated can help speed up the digestive process by increasing the food's surface area for digestive enzymes and helping to soften the food particles, respectively, Nandy said. In addition, "exercise helps increase gut motility and promotes peristalsis, which is the rhythmic contraction of digestive muscles," Nandy said. Conversely, peristalsis can slow down during periods of inactivity.

A person's age and stress levels can also affect digestion. With age, adults tend to produce less stomach acid and digestive enzymes, while their guts become less motile, she said. "Stress and anxiety can also increase gut transit time by altering gut motility and reducing gastrointestinal blood flow," she added. Having a "nervous stomach" reflects an activation of the fight-or-flight system, which generally suppresses digestion in the stomach and small intestine while stimulating the large intestine.

And finally, certain medical conditions and medications can either speed or slow digestion. For example, diabetes is the most common cause of gastroparesis, or "delayed stomach emptying," which makes food linger in the stomach for a long time. Certain medications, including opiates and anticholinergic drugs, which suppress nerve signals responsible for involuntary muscle movements, can slow gut transit and cause constipation, Nandy said.

This article is for informational purposes only and is not meant to offer medical advice. 

Nothing clears a room like a smelly fart. Even though this gas, known scientifically as flatus, is a part of our daily lives, we still know surprisingly little about what goes into it. So which foods make us the gassiest, and which ones make for the stinkiest farts?

A smelly fart usually starts with carbohydrates, especially insoluble ones that make it through the stomach and upper intestinal tract without being absorbed, Dr. Ali Rezaie, a gastroenterologist at Cedars Sinai in Los Angeles, told Live Science. Bacteria populating the colon thrive on these unabsorbed sugars, which are "like high-octane fuel for them," Rezaie said.

Although these carbs like fiber and starch weren't absorbed higher in the gut because our bodies lack the enzymes to break them down, bacteria, like those in the phylum Firmicutes in the colon, digest them easily. In feasting on these carbs, the bacteria produce gas, which can turn into farts.

However, not all of the gas that bacteria produce from food become smelly farts. A person produces about 30 to 91 cubic inches (500 to 1,500 milliliters) of flatus every day regardless of their diet, and over 99% of those gases are odorless, Rezaie said. Unscented gases — like methane, carbon dioxide and hydrogen — all contribute to farts, but gassiness doesn't necessarily correlate with stench.

Related: If the brain doesn't feel pain, why do headaches hurt?

Offensive gases include hydrogen sulfide, known for its rotten-egg smell; indoles; and skatoles, "which, as the name implies, smells like poo," Dr. Eric Goldstein, a gastroenterologist at Mount Sinai Medical Center in New York City, told Live Science. But, when it comes to converting food into gas, it's not a one-to-one conversion rate in the gut.

"You can eat a ton of sulfur-containing compounds and have bacteria present that are making hydrogen sulfide," but "your flatulence will not smell like hydrogen sulfide," Goldstein said. Instead, the hydrogen-sulfide-producing bacteria may be counterbalanced by other bacteria feasting on that very compound. Sulfur-rich foods include legumes (such as lentils, beans and peas) and brassicas (such as broccoli and cabbage). These fibrous veggies also contain insoluble carbs that bacteria in the colon may convert into stinky gas.

Goldstein and Rezaie emphasized that many factors affect the volume and smell of flatulence. While we can assess common compounds in both foods and farts, some people have unique food sensitivities based on their gut microbiome. Insoluble sugars generally provide the basis for noxious gas, but there are no universal foods that become a polluting toot from every rear end.

"The gas production of bacteria in our gut is not just dependent on what you eat," Rezaie said. "It's all dependent on what other gas-producing bacteria in the gut that are feeding them other gases." Other factors — like gut motility, changes in bacterial composition, and how long it takes food to move through the gut — also influence how a fart might stew. What's more, farts also comprise swallowed air and gases diffused from the bloodstream, which are also odorless. These factors mean that a fart is more likely to be heard than smelled.

Disorders and intolerances also affect how bacteria produce gas. For example, in people who are lactose intolerant, the carbohydrate lactose makes it all the way to bacteria in the colon, which may leave someone farting up a storm that may or may not be smelly. Goldstein pointed to the FODMAP diet, a temporary elimination diet, as one way to reduce extreme cases of flatulence in those who are prone to it.

Still, Goldstein underscored that "there's really no clear one size fits all" when it comes to diet and farts, as myriad factors in each person's body interfere with all flatus. The measure of whether to seek help depends on how much  flatulence disrupts someone's everyday life. On the other hand, farts — even stinky ones — are inevitable, and we can learn to forgive others and ourselves.

Cilantro is one divisive herb: People either love it or hate it. Julia Child disavowed the stuff, claiming it had a soapy taste in 1955 — and the comparison stuck. Between 3% and 21% of people, depending on their location in the world, dislike cilantro for its soapiness. But how can people have such vastly different sensations from the same herb?

Genetics plays a major role, it turns out.

It's no surprise that people have different reactions to the same food, but usually, they're responding to the same taste experience. Chilis are a classic example: Everyone experiences the burning sensation, and only some people like it.

Cilantro is different, said John Hayes, a sensory expert and professor of food science at Penn State. People describe a fundamentally different experience or sense when they consume the herb. "Nobody knows exactly which genes are involved in cilantro preference," Hayes said. But in a large observational study a specific olfactory receptor gene, OR6A2, has been implicated.

The study was done by 23andMe. The consumer DNA testing company looked at a "crude measure of sensory phenotype but over a very large population," Hayes explained.

Related: Why do lobsters turn red when they're cooked?

A 23andMe team surveyed thousands of respondents about their cilantro preference and identified a single nucleotide polymorphism (SNP) associated with cilantro aversion. The SNP lies in a cluster of genes that code for olfactory receptors, researchers at the company reported in the journal Flavour in 2012.

One of those genes encodes for the receptor OR6A2, which happens to specifically bind to aldehydes that give cilantro its specific odor, according to 23andMe.

"People aren't quite sure exactly which of the many volatile aromatics cause the off-note, the soapy note [in cilantro]," Charles Spence, a professor of experimental psychology and gastrophysicist at the University of Oxford told Live Science. But the culprit seems to be some of these cilantro-specific aldehydes, organic compounds that can pack a pungent odor.

The 23and Me study also found that cilantro preference is likely heritable and varies by ethnicity, according to 23andMe's findings. Of the Southern and Northern European respondents, about 13% said cilantro tastes like soap. But only 8% of East Asian respondents and 4% of South Asian respondents were anti-cilantro. Since cilantro is a featured herb in South and East Asia, "it may be that cultures that experienced less soapiness would be more likely to adopt it," Hayes said.

Interestingly, there are records of people complaining about cilantro way back in the 1500s and 1600s, Spence said. But "how they describe it has completely changed." Before the off-taste was deemed as soapy, cilantro haters said the herb smelled like bedbugs, he said.

This change may be because our predecessors were more familiar with bedbugs than we are today. And around the time of Child's remark, soap had become more synthetic; new detergents would have contained different aldehydes than traditional soaps, maybe more similar to those in cilantro, Spence said.

Aversion to other foods, too, is influenced by genetics. A genetic variation in the receptor OR7D4, for instance, makes some people more sensitive to the smell of boar taint, an unpleasant odor in male pigs caused by the hormone androstenone. If androstenone is in pork, which happens if the male pig isn't castrated, those who are sensitive to boar taint will find the pork very unappetizing, Spence said.

On the taste side, scientists know that of the 25 genes that encode bitter taste receptors in humans, four or five contain functional polymorphisms, Hayes said, meaning there are several mutations that change the way some people experience bitter food. The gene TAS2R38 determines if you like bitter greens, like kale and Brussels sprouts, or a hoppy beer, And TAS2R31 influences preference for grapefruit juice and quinine in tonic water. "It also predicts whether you are going to like saccharin," the sweetener in Sweet'N Low, Hayes said.

Even though cilantro preference is innate, it's not concrete. Just like other food preferences, you can grow accustomed to cilantro with repeated exposure. "Biology is not destiny," Hayes said. So, even if you hate cilantro now, it's never too late to change.

If you deal with constant breakouts of pimples, you might be tempted to eliminate sugar from your diet. After all, that's the advice offered by various online sources, and numerous studies seem to back it up. But the bittersweet truth is that cutting out sugar likely won't be enough to solve your pimple problem.

This raises a question: Does eating sugar actually cause acne? Because of the interplay between many factors involved in acne, pointing to sweet treats as the sole culprit may be an oversimplified explanation, experts told Live Science.

Acne results from complex interactions among hormone levels, oil glands, clumping skin cells and the skin microbiome, the community of microorganisms on the skin, combined with lifestyle factors like stress and diet, said Dr. Anjali Mahto, a consultant dermatologist and spokesperson for the British Association of Dermatologists.

Due to this ensemble of factors, "dietary changes alone are generally not recommended as the only treatment for patients with acne," Dr. Tanya Greywal, a dermatologist and instructor at the University of Washington, told Live Science in an email. "Many times topical or oral medications are also necessary."

Related: Does dairy cause acne?

Nutritional studies have found a link between sugar intake and acne. Studies from China, France and Turkey tracked participants' diets and spotted correlations between the two. However, those observational studies don't prove that sugar causes acne; other shared factors may underlie the results.

In a randomized, controlled trial in South Korea, participants with acne who were placed on a reduced-carb, low-glycemic diet experienced slight improvements in their acne compared with participants on carb-heavy diets.

However, it's hard to draw definitive conclusions because many acne studies have experimental design flaws that make their results difficult to interpret. For example, participants self-diagnosed with acne may have visually similar, yet distinct skin conditions, like folliculitis. Therefore, studies may include people who don't actually have acne.

In observational studies that explore correlations between diet and acne, participants typically complete surveys about their meals. However, people are "not very good at recording exactly what they've had or the amounts," Mahto told Live Science. Surveys also tend to be taken at a few points in time and, therefore, largely ignore how dietary patterns vary over long periods. To complicate things, sugary foods also often contain other ingredients that possibly influence acne, such as dairy or cocoa.

These limitations raise doubts about the link between sugar and acne. Nevertheless, dieting is a common strategy for managing the condition because "people like to try and control the things that they can," Mahto noted.

Other acne triggers are often unaccounted for in nutritional studies and less easily controlled. For example, a buildup of the stress hormone cortisol can worsen acne, or people may have underlying conditions that provoke acne, such as polycystic ovary syndrome (PCOS), a condition involving insulin resistance and excessive synthesis of male hormones by the ovaries.

Surges in male hormones, like testosterone and its byproduct dihydrotestosterone are the primary triggers for acne in both sexes. High male hormone levels in the skin cause oil-producing glands to churn out more of a moisturizing substance called sebum. Pimples appear when hair follicle pores become clogged with an excess of this oily amalgam. Under these conditions, skin cells become sticky and clump together, adding to the clog. This creates a supportive environment for bacteria, mainly Cutibacterium acnes, some strains of which provoke inflammation, giving zits their signature red, swollen appearance.

Foods that trigger a sudden uptick in blood sugar levels could theoretically boost the production of these acne-causing hormones. High-glycemic foods, like white bread, contain little fiber and release sugar into the blood rapidly, triggering an insulin response. This fuels a spike in insulin growth factor-1, a hormone that promotes male hormone production. Meanwhile, high-fiber foods, like most fruits, are considered low on the glycemic index and release sugar into the bloodstream gradually without triggering an insulin response.

Related: Which fruits are good for diabetics?

Following this theory, sugar may be less likely to trigger acne if it's consumed with fiber. However, although insulin surges can set off acne-triggering hormonal changes, the confounding factors that creep into studies muddy our understanding of how strongly sugar drives breakouts. Overindulging on sugary treats probably does contribute to acne, but it's difficult to weigh its effect against other triggers.

In an effort to treat their acne, people often self-manage their diet in lieu of consulting a dermatologist, and by cutting out sugar and other foods alleged to provoke acne, they could develop worryingly restrictive eating behaviors. And although "eating well for your skin is the same as eating well for every other organ of your body," Mahto said, obsessing over what you eat probably won't cure your acne.

This article is for informational purposes only and is not meant to offer medical advice.

Mocktails and so-called zero-proof beverages are growing commonplace on menus as more people opt to follow a "sober curious" or strictly teetotal lifestyle.

Many are familiar with the "Dry January" challenge to stop drinking alcohol for a whole month, but recently, the trend of saying goodbye to the dreaded hangover hasn't stopped with New Year's resolutions, especially amongst young people. Over the past two decades, the number of American undergraduate students who report abstinence from alcohol has risen by 8%, and in the U.K. in 2019, adults aged 16 to 24 were most likely to be teetotal, with 26% saying they never drink. 

People quit alcohol for many reasons: for some it's the calories, others, the risk of liver damage, increased blood pressure and potentially cancer. But what happens to the body when the average drinker calls it quits? 

Related: What does alcohol do to the body?

Given how many variables there are, it is hard to define an "average" drinker. The Centers for Disease Control and Prevention (CDC) describes "drinking in moderation" as having no more than one drink a day if you're a woman or two drinks a day if you're a man, on the days that you drink alcohol. Two-thirds of adult drinkers, however, say they exceed these levels at least once a month, a 2014 study found. 

The agency defines "binge drinking" as consuming at least four drinks in a 2 to 3 hour sitting, for women, and at least five drinks in the same time for men; "heavy drinking" is having at least eight or 15 drinks a week for women and men, respectively. A standard drink roughly translates to 12 ounces (0.35 liters) of beer at 5% alcohol by volume (ABV), or 5 ounces (0.14 L) of wine at 12% ABV. 

One way to represent the average drinker may be to focus on people who don't have a history of alcohol dependence. This is exactly what one study, published in the British Medical Journal, did in 2018.

Scientists recruited 94 volunteers who were on average 45 years old and asked them to stop drinking for a month. Before the challenge, participants were defined as "moderate to heavy drinkers" who drank around 258 grams of alcohol a week, roughly equivalent to about 18 standard drinks. No participants had a history of known liver disease or alcohol dependence. 

After a month, those who refrained from drinking experienced a range of positive health benefits not seen in a similar group of people who continued to drink. On average, the abstainers' blood pressure decreased by 6%, they lost around 3.3 pounds (1.5 kilograms) and their insulin resistance, which reflects a person's risk of developing diabetes, fell by 25%. 

"We didn't note this in the report but they also felt better, their concentration improved and they were able to sleep better," Dr. Kevin Moore, study author and professor of hepatology at University College London, told Live Science. The team saw these results after adjusting for changes in diet, exercise and smoking, so the changes could be linked to people's alcohol use. 

They also noticed that levels of proteins in the blood that promote cancer growth, namely epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) decreased by around 73% and 41%, respectively. Moore hypothesized that instead of causing cancer to develop in the first place, these findings may suggest that alcohol instead promotes cancer's growth once it gets a footing in the body. To confirm this speculation, however, the team would need to conduct a long-term study of moderate drinkers, the authors noted in their report. 

It is still unknown whether these positive effects of abstinence persist beyond a month, but Moore speculated it could be possible. "It's quite clear that alcohol has a physiological effect on the body, so I'd be surprised if all those effects just wore off," he said. 

So, does this mean people should stop drinking altogether?

"If you have cancer and you're worried about it growing then you should stop," he explained. This is common guidance given to cancer patients. For the wider population, he emphasized that when you stop drinking, you not only feel better but you also sleep better and your physical health improves. One downside of quitting for some though, he said, could be the social side of drinking and not wanting to feel left out. 

One important caveat is that Moore's study looked only at drinkers without a history of alcohol dependence. However, other research suggests that brain regions damaged by long-term alcohol abuse can start to repair themselves after people stop drinking.

In a 2023 study published in the journal Alcohol, scientists discovered that the outer layer of the brains of people with alcohol use disorder, which can thin as a result of alcohol abuse, regained its thickness after approximately seven months of abstaining from alcohol. Before abstaining, the study participants were drinking around 13 drinks a day over 12 months, Vice reported. 

The beneficial effects of abstaining cropped up even earlier, however. 

"Our team and other researchers have observed rapid recovery over two to four weeks of abstinence, for brain volume in multiple regions across the brain, in those with an alcohol use disorder," Timothy Durazzo, lead study author and professor of psychiatry and behavioral sciences at Stanford University, told Vice. 

Nevertheless, people who have AUD should take extra care before suddenly quitting or significantly decreasing their intake as they can experience symptoms of alcohol withdrawal. This is where the central nervous system becomes so reliant on the depressive effects of alcohol that, when a patient stops drinking, their brain stays in a "hyperactive" state. This can lead to symptoms including anxiety, insomnia and irritability, and in more serious cases, hallucinations, seizures and potentially death. 

"If an individual experiences shakiness and discomfort the morning after drinking, or drinks alcohol throughout the day, then going cold turkey could be dangerous," Katie Witkiewitz, a professor of psychology at The University of New Mexico, told Live Science in an email. 

In these cases, she said that talking with a healthcare provider about taking specific withdrawal medication could be helpful. Talk therapy, either as an individual or as part of a group, can also offer support through the process of quitting. 

This article is for informational purposes only and is not meant to offer medical advice.

Editor's note: This article was updated on Jan. 1, 2024 with information from a study published in 2023. The story was first published on Aug. 16, 2023.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

If you miss your morning cup of joe, your temples may start throbbing. If you drink more than normal, that could cause a headache, too. And somehow, a strong cup of coffee can also stop some migraines in their tracks. 

So is caffeine the culprit or the cure for headaches? Is the problem too much or not enough? The answer: all of the above. 

The key to understanding caffeine is to remember that it's no ordinary ingredient. Caffeine is a psychoactive substance, said Dr. Richard Lipton, a professor of neurology at Albert Einstein College of Medicine in New York City. It has stimulating and vasoconstricting properties, meaning it speeds up brain activity and causes veins in the head to narrow, which help explain caffeine's roles in headaches — both as instigator and reliever. 

Related: Does coffee really give you an 'energy boost'? 

Caffeine as headache treatment 

Caffeine's ability to relieve a withdrawal headache or halt a migraine is well established; it's a key ingredient in multiple over-the-counter and prescription drugs, including headache-specific medicines like Excedrin. 

"It's not a pain reliever in its own right, but when combined with pain relievers, it makes them more effective," Lipton told Live Science. While caffeine's synergy with pain relievers is not fully understood, it could be related to caffeines activity in the brain.

The caffeine molecule binds to adenosine receptors in the brain and spinal cord. Normally, adenosine, a building block in DNA's molecular cousin RNA and in the main chemical fuel used by the body's cells, binds to these receptors, but it's blocked by ingested caffeine.  

By taking up the seats adenosine would normally occupy, caffeine blocks the molecules' effects. While adenosine slows nerve activity, caffeine increases it. Adenosine increases blood flow and causes blood vessels to widen, while caffeine constricts them; as some headaches partly stem from vasodilation in the head, caffeine's role as a vasoconstrictor may partly explain its effects. 

However, adenosine also plays a complex role in pain transmission, sometimes quelling pain signals and sometimes promoting them, so caffeine may also relieve headaches by messing with this signaling. Studies also show that, when taken with caffeine, pain relievers like acetaminophen are absorbed faster and their effects may last longer. In a study in which providers and patients didn't know whether they received an active pill or a placebo, caffeine with ibuprofen provided better and faster pain relief than ibuprofen alone.

However, caffeine's pain-killing abilities vary widely depending on how much people normally consume, according to Stanford Health Care. People develop a tolerance with frequent caffeine use and can then become dependent on caffeine's effects. This minimizes its headache-relieving effects. 

Related: What are the different types of headaches? 

Not enough or too much

On the flip side, caffeine can also cause headaches — both when people consume less than they normally would and when they consume too much. 

In the former case, headaches can occur because, with daily use, caffeine starts to change the brain's structure. "When your receptors are chronically exposed [to caffeine]," Lipton said, "then your brain doesn't function normally unless the caffeine is around."

Studies suggest that regular caffeine consumption increases the number of adenosine receptors in a person's brain, making a person more sensitive to adenosine's effects. Withdrawal headaches occur because the body becomes used to the vasoconstriction that comes with daily caffeine, and without it, those blood vessels suddenly swell, which can cause headaches. 

The good news is that once you catch up on your caffeine, these headaches usually go away — or after a period free from caffeine, the brain's number of adenosine receptors falls, as do the symptoms of withdrawal. 

Excess caffeine can also trigger headaches. Headache is one of the many side effects of caffeine overdose, and for some migraine patients, caffeine can actually trigger an attack. However, while there's rigorous evidence behind caffeine withdrawal headaches and caffeine's benefits in combination with painkillers, the reason excessive caffeine causes headaches is less established, Lipton said. But it's a phenomenon neurologists like Lipton have observed in the clinic, he said. 

To be safe, the Food and Drug Administration says healthy adults should limit their caffeine intake to 400 milligrams — the equivalent to four or five cups of coffee — per day.  But it's important to note that individuals' sensitivity to caffeine can vary. 

"Caffeine is definitely this two-edged sword," Lipton said. It can be mood-boosting and productivity-enhancing, and sometimes pain-stopping, but overuse and overdependence are fast paths to a throbbing headache. 

This article is for informational purposes only and is not meant to offer medical advice.

You're at a restaurant and just devoured a hearty meal. With an uncomfortably full stomach and seemingly tighter pants, you can't fathom eating another bite — that is, until the dessert tray passes by and your hunger returns. But why does the sight of sweet treats open up a mysterious empty compartment in your tummy? 

The secret is variety, according to Len Epstein, a SUNY distinguished professor of pediatrics and chief of the Division of Behavioral Medicine at Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo in New York. 

"Part of the reason why people stop eating a meal is that they're tired of the food; they've eaten it [and] there's no more stimulation," Epstein said. "They know exactly what it tastes like. But if you introduce a new flavor, smell or even texture into the mix, "it's easy to overcome that feeling of 'Oh, I'm full,'" Epstein told Live Science. 

Related: Why do our stomachs growl?

This phenomenon is called sensory-specific satiety, which a person can experience when their interest in a certain food declines because they have eaten it repeatedly, while a novel food item may become more appealing. For example, in a 2011 experiment led by Epstein, 32 women were assigned to receive a macaroni-and-cheese meal either five times in one week, or once a week over five weeks. The researchers found that women who were presented with mac and cheese daily ate less of it than women who were given it once a week. 

In a separate study published in 2013, however, Epstein split 31 children into three groups: one that received the same mac and cheese for five days, another group that was given different brands of mac and cheese, and a final group that was provided with a variety of energy-dense foods, such as chicken nuggets and cheeseburgers. The children with the variety of options consumed much more than the kids who were offered only mac and cheese. This pattern is the same when people are exposed to sweet desserts after a salty meal, according to Epstein, or if you were eating a buffet with a wide variety of dishes. 

"You can keep presenting new foods and have people keep eating until the point where they just can't eat anymore," he said. "But that is one of the reasons for why people eat more than they need to." 

Some experts believe this desire for variety is an evolutionary adaptation that people acquired to get essential nutrients, such as vitamins and proteins, from different food groups. 

"In the long run, we need a good mix of nutrients," Barbara Rolls, director of Penn State's Laboratory for the Study of Human Ingestive Behavior, told Live Science. "Now, where it backfires on us is with the big variety of large portions of calorie-dense foods available to us. The variety does stimulate overconsumption, and so it's potentially contributing to obesity."

When a person consumes a sugary dessert, they also get a hit of dopamine, a chemical in the brain that is associated with feelings of reward and pleasure. If eating dessert is a regular part of your daily routine, "the release of dopamine shifts from after you eat the food to the anticipation of eating the food," Epstein said. This is what constitutes a craving, and it may make you more likely to reach for a slice of pie at the end of a big meal. 

If you are trying to cut back on your post-dinner junk-food fixes, there are a few ways to use sensory-specific satiety to your advantage, according to Rolls. For example, you can keep other sweet foods around, such as fruits, so you are still introducing variety into your diet but in a healthier way. 

"What you need to do … is keep a good variety of healthy, low-calorie [dense], nutrient-rich foods readily available that you enjoy so that when you get the munchies, you have a good variety to choose from," Rolls said.

No, the artificial sweetener aspartame is not a possible carcinogen to humans, the U.S. Food and Drug Administration (FDA) said Friday (July 14). 

The regulator's statement came on the heels of a ruling issued by an arm of the World Health Organization (WHO), which classified the ubiquitous sweetener as possibly cancer-causing.

The WHO agency, called the International Agency for Research on Cancer (IARC), made its call based on a handful of studies in humans, mice and rats, as well as cell-based studies, which the agency says link aspartame to cancer. Each line of evidence was "limited," meaning the IARC couldn't confidently rule out the possibility that the results were skewed by "chance, bias, or confounding." Having also reviewed the data, the FDA flagged "significant shortcomings" in the studies on which the IARC relied, according to its statement.  

"Aspartame is one of the most studied food additives in the human food supply," the FDA statement continues. "FDA scientists do not have safety concerns when aspartame is used under the approved conditions," meaning when people adhere to the established safe consumption limit of no more than 40 milligrams of aspartame per 2.2 pounds (1 kilogram) of body weight per day. (To exceed that daily limit, a 150-pound (68 kilograms) person would need to down more than a dozen cans of diet soda.) 

So what gives? What prompted the IARC to make this contentious call?

Related: Is Diet Coke bad for you? 

In an exclusive published two weeks ago, Reuters reported that the IARC was planning to add aspartame to its list of possible carcinogens. Now, with the publication of a new report in the journal The Lancet Oncology, the IARC has made its declaration official, and aspartame is now listed among hundreds of other possible carcinogens — which include aloe vera leaf extract, "traditional Asian" pickled vegetables and the radio-frequency electromagnetic fields associated with cellphones.

The IARC's controversial carcinogen ranking system has long been criticized as misleading and confusing. In the case of aspartame, the IARC placed the sweetener in group 2B, the "possible" carcinogens, largely based on three observational human studies that explored potential links between cancer and drinking artificially sweetened beverages, which served as a proxy for aspartame exposure. 

One study conducted in Europe linked artificially sweetened soft drinks to a heightened risk of hepatocellular carcinoma, a type of liver cancer. Two U.S. studies found a similar increase in liver cancer risk linked to artificially sweetened beverages, although one of the two only observed this effect in people with diabetes. 

The IARC combined this human data with rodent studies that linked aspartame to both malignant and benign tumors in mice and rats, but they noted weaknesses in the design of the animal studies. They also noted limited evidence from lab dish studies that suggest aspartame "exhibits key characteristics of carcinogens."

Taken altogether, the evidence of carcinogenicity isn't very strong.

This is the first time the IARC has evaluated aspartame, but another arm of the WHO — the Joint WHO and Food and Agriculture Organization's Expert Committee on Food Additives, or JECFA — has evaluated the sweetener several times and set an acceptable daily intake level. JECFA reviewed the data on aspartame at the same time as the IARC and has maintained that the established intake level is safe. 

Crucially, "JECFA also considered the evidence on cancer risk, in animal and human studies, and concluded that the evidence of an association between aspartame consumption and cancer in humans is not convincing," Dr. Moez Sanaa, the WHO's head of the Standards and Scientific Advice on Food and Nutrition Unit, said in a statement. 

In fact, JECFA "concluded that there was no convincing evidence from experimental animal or human data that aspartame has adverse effects after ingestion." That's partly because, during digestion, aspartame breaks down into metabolites that the body readily absorbs from other common foods, and thus no aspartame enters systemic circulation, the committee reported. The team also concluded that, based on various experimental studies, the sweetener doesn't damage DNA and there isn't evidence of another mechanism whereby eating aspartame could cause cancer. 

In its evaluation, JECFA considered how much aspartame people actually consume in a day and "noted that even the high estimates of consumption levels in children and adults are considerably below" the established, safe threshold, according to a commentary published alongside the IARC's report.

Along with the JECFA and the FDA, food safety regulators such as Health Canada and the European Food Safety Authority have also thoroughly evaluated aspartame in the past and maintain that the established daily intake levels are safe. 

When you haven't eaten in a while, your body has ways of reminding you that it needs fuel. Often, the stomach nudges you toward your next meal by making loud gurgling noises. But why, exactly, do our stomachs growl?

"Stomach growling is due to peristalsis," Tiffany Weir, professor of food science and human nutrition at Colorado State University, told Live Science. 

Peristalsis is a series of wavelike muscular contractions that propel gas, food and liquids along the hollow tube of the digestive tract. The human digestive tract, which includes the mouth, esophagus, stomach, intestines and rectum, is essentially a long, muscular pipe. To get food from one end to the other, the muscles built into the lining of this tube contract in a sequence, one set of muscles after another, which pushes digestive contents along. 

Stomach growling, or borborygmi, is the sound caused by these muscle contractions, and they don't just happen when you are hungry. 

"Your stomach can growl when it's hungry or when it's full because we have hormones that regulate our appetite and trigger peristalsis," Weir said. Immediately after a meal, there is a lot of peristalsis going on. There are an average of three waves per minute in the stomach and 12 along the small intestine. As food is pushed through the digestive tract, it is mixed and churned for easier digestion, and the mixing of solids and liquids during digestion is not a silent process. 

Related: Will eating pet food kill you?

This peristaltic action often goes unnoticed because the contents of the stomach and intestines muffle any sound the digestive tract may make. But an empty digestive tract is much noisier, which may explain why stomach growling is noticeable when someone is hungry, making it commonly associated with hunger.. 

According to the National Institutes of Health, when the stomach has been empty for a few hours, it begins to secrete a hormone called ghrelin. When this hormone reaches the brain, it triggers feelings of hunger and stimulates peristalsis in the digestive tract. 

The reason the stomach and intestines might contract in the absence of food may be to clear out any excess liquid, solid or microbial debris that may be lingering in the stomach or intestines, Mark A. W. Andrews, a professor of physiology and associate director of the Independent Study program at the Lake Erie College of Osteopathic Medicine in Pennsylvania, said in an article for Scientific American. 

This peristalsis is much slower than when the digestive tract is full, as it only occurs about once every 20 minutes. However, because there is more air than solid material in the tract, loud rumblings can often be heard when the digestive tract is empty. 

Sometimes, stomach growling and gurgling is caused by digestive problems. Incomplete digestion of certain foods, like plant material, such as beans, and dairy products, can produce excess gas that amplifies the sounds of peristalsis. Digestive illnesses like gastroenteritis can cause diarrhea, which involves increased peristaltic action in an attempt to clear the intestines, which can also be quite noisy. 

Illnesses aside, stomach rumbling is a common and harmless side effect of the way the human digestive system operates. 

This article is for informational purposes only, and is not meant to offer medical advice.

An agency within the World Health Organization (WHO) will soon name the widely used artificial sweetener aspartame a "possible carcinogen," based on a review of 1,300 studies, Reuters reported, citing information from two sources who are knowledgeable about the process. 

But don't panic: The arm of the WHO that did the review, the International Agency for Research on Cancer (IARC), uses a classification system for possible and known carcinogens that is notoriously confusing and often misleading, Reuters noted. Science writer Ed Yong summed it up well in a 2015 Atlantic article, in which he wrote, "Perhaps we need a separate classification scheme for scientific organizations that are 'confusogenic to humans.'" 

Here's what you need to know.

Problems with the IARC's rulings

The IARC doesn't analyze how much of a product a person can safely consume before it poses a health risk, according to Reuters. When it comes to aspartame, the answer is a lot: Past assessments suggest that a typical, 150-pound (68 kilograms) person could safely consume the equivalent of the aspartame contained in more than 13 cans of Diet Coke a day. 

Related: Non-sugar sweeteners don't help with weight loss and may come with health risks, WHO says

The arm of the WHO that handles such assessments — the Joint WHO and Food and Agriculture Organization's Expert Committee on Food Additives, or JECFA — has ruled on aspartame many times before. In its most recent review, the agency again held that the sweetener is safe to consume and set the acceptable daily intake at zero to 40 milligrams per 2.2 pounds (1 kilogram) of body weight. That translates to about 2,730 milligrams per day for a 150-pound person. 

Again, this recommendation reflects how much aspartame can be consumed before it poses any health risk — not specifically cancer. Various agencies, including the European Food Safety Authority and U.S. Food and Drug Administration, have not found any definitive link between aspartame consumption and an increased risk of cancer, the American Cancer Society states.        

Interestingly, JECFA is also reviewing the available data on aspartame and will announce its findings July 14, the same day the IARC is expected to rule on the artificial sweetener. 

The IARC ranks substances as carcinogenic, probably carcinogenic, possibly carcinogenic or not classifiable. These classifications serve as a rough way to rank the strength of the evidence linking a substance to cancer in humans; this evidence includes studies of humans, human cells and tissues and lab animals, as well as studies of the substances' similarity to known or probable carcinogens. The rankings aren't related to how much a substance might increase cancer risk, but how conclusively the IARC can say it causes cancer at all.

Tobacco, asbestos and processed meat are all classified as carcinogenic, meaning the IARC determined there's conclusive evidence that they can cause cancer in humans, even though the degree of risk differs among these substances. 

The IARC considers glyphosate, the active ingredient in the weed killer Roundup, a "probable" carcinogen, meaning there's inconclusive or inadequate evidence that it can cause cancer in humans and either sufficient evidence showing it causes cancer in animals or strong evidence that it has similar characteristics to known or probable human carcinogens. (Regulatory agencies have contested the IARC's ruling on glyphosate, Reuters noted.)

For "possible" carcinogens, there's inconclusive or inadequate evidence they can cause cancer in humans but sufficient evidence that they cause cancer in animals or strong evidence that they have carcinogen-like characteristics. In some cases, something can rank as a possible carcinogen if there's "strong" evidence from cell and chemical studies but inadequate evidence in animals and humans. 

Sources told Reuters that aspartame will fall into this category, alongside the radiofrequency electromagnetic fields associated with cellphones. (Note that non-IARC authorities have said there's no or insufficient evidence linking cancer to cellphone use.)

Listing aspartame as a possible carcinogen is intended to motivate more research, sources close to the IARC told Reuters. Read more about the IARC's upcoming decision in Reuters. 

Lab-grown meat, made from chicken cells cultured in steel tanks, can now be produced and sold in the U.S. for the first time.

On Wednesday (June 21), two California-based companies — Upside Foods and Good Meat, a subsidiary of Eat Just — became the first in the nation to get approval from the U.S. Department of Agriculture (USDA) to produce and sell lab-grown chicken products, The Washington Post reported. Joinn Biologics, a manufacturing partner of Good Meat, also received approval to cultivate the meat.

The process of making lab-grown meat, also called "cultured" or "cultivated" meat, begins with sampling cells from the tissues of a living animal, according to the USDA. Collecting the cells "typically does not permanently harm or kill the animal," the department notes. The cells are then screened and stored in a cell bank. Cells are later collected from the bank and moved to large, enclosed vessels — often steel tanks, according to The Associated Press. 

The tanks act as bioreactors where the cells can rapidly multiply. Manufacturers supply the cells nutrients, surfaces for the cells to grow upon, and protein growth factors that cue the cells to differentiate into muscle, fat and connective tissues like those found in a regular chicken, the USDA statement explains. Once differentiated and ready for harvest, the cells are collected from the tanks and "prepared using conventional food processing and packaging methods."   

Related: Do you need to eat meat to get protein? 

In 2019, the U.S. Food and Drug Administration and the USDA's Food Safety and Inspection Service established a regulatory framework to ensure that lab-grown meat is safe and truthfully labeled. As part of this approval process, both Upside Foods' and Good Meat's cultivated chicken products have been assessed and confirmed to be safe for human consumption. On Wednesday, both companies received a "grant of inspection," the final USDA seal of approval needed to bring their products to market, NPR reported.

For now, the lab-grown chicken won't be found in any average grocery store, and it will be pricey. Upside Foods is partnering with Dominique Crenn, owner of the three-Michelin-starred restaurant Atelier Crenn, who will serve the cultivated meat at Bar Crenn in San Francisco. Similarly, Good Meat's product will be served in a yet-undisclosed restaurant of celebrity chef José Andrés, one of the company's board members, according to NPR.

Following this initial rollout in fancy restaurants, Dr. Uma Valeti, Upside founder and CEO, told Yahoo Finance that the company aspires to eventually "beat the conventional prices" of traditionally raised meat and foresees that Upside's products will be "at parity" with conventional meat products within five to 15 years.

In addition to the fact that cultivated meats are "slaughter-free," proponents of the products tout their potential environmental benefits, compared with conventionally raised meat. However, some scientists, including a team at the University of California, Davis, have pointed out that cultivated meat doesn't necessarily produce fewer carbon emissions than conventional livestock farming, in part due to the energy-intensive process currently required to make the growth medium used during production. 

On top of this, it's not yet clear how companies can feasibly scale up production to make lab-grown meat available for general consumption, CNBC reported.