The growth of a pre-Inca civilization known as the Wari may have been aided by psychedelic-laced beer, researchers propose in a new study.

The Wari flourished from roughly A.D. 600 to 1000 and are known for their mummified burials, human sacrifices, and elaborate objects created out of gold, silver and bronze. They also built cities such as Huari and Pikillaqta, which contained temples and dwellings for elite inhabitants, and controlled much of Peru as well as parts of Argentina and Chile.

In the new study, published Monday (Oct. 6) in the journal La Revista de Arqueología Americana (The Journal of American Archaeology), the researchers suggest that Wari rulers used psychedelics mixed in beer to help grow their empire. They explain that the "afterglow" — the long-term effect of drinking the mix — would have lasted weeks and that communal feasts where it was drunk would have brought people together. While the body may excrete psychedelics quickly, the aftereffects can last for days or weeks.

The study authors noted that the remains of seeds from a plant named Anadenanthera colubrina (also known as vilca) have been found at Wari sites, including near the remains of beer made from a plant called Schinus molle. Mixing the vilca, which is known to produce a psychedelic effect, with the beer would have "lessened but extended the high," Justin Jennings, a curator of South American Archaeology at the Royal Ontario Museum and co-author of the paper, told Live Science in an email.

In the paper, the authors noted that scientific studies of similarly acting psychedelics found that people who took them tended to display "greater openness and empathy."

These traits "would have been highly desirable for a Wari political system that depended on friendly, routine face-to-face interactions between people who had once been strangers or even enemies," the researchers wrote in their paper.

People would have drunk the psychedelic beer together at communal feasts held within enclosed areas at the residences of Wari officials. This shared experience would have enhanced the event, the researchers said.

"When guests came to the Wari compounds, they gathered in patios that could only comfortably fit a couple dozen people," the team wrote. "Except for a patch of sky, they were cut off from the rest of the world in a high-walled interior space — this was the place where they would spend hours together drinking, eating, talking, and praying," the researchers wrote in their paper.

"The hours that participants spent together must have been an unforgettable collective experience that forged strong bonds between participants," they added.

Building an empire

The regular, widespread use of the psychedelic beer and its afterglow played a key role in the Wari Empire's consolidation of political power, said Jacob Keer, an independent scholar and co-author of the paper.

The "long-term psychological effects of drinking vilca beer a few times a year could constitute a new cognitive normal, instilling increased openness and empathy in feast participants," the researchers wrote in their paper. "Within the context of an expanding empire where violence and animosity was commonplace, the lingering effects [of consuming it] may have been integral to Wari legitimization and consolidation."

Scholars who were not involved with the research had mixed reactions to the conclusions in the paper, however. Patrick Ryan Williams, director of the School of Human Evolution and Social Change at Arizona State University, said the team put forward an "interesting hypothesis" but cautioned that we can't be certain that vilca was actually mixed into beer.

"I am not convinced, however, that the discovery of vilca seeds in an area where molle beer was consumed constitutes evidence of vilca being included as an ingredient in beer," Williams said, as it would be like finding cocaine on the floor of a nightclub and assuming the drug was put into drinks.

"When a chemical trace for vilca is found in the ceramic pores of drinking cups, I will be more open to the premise presented here," Williams said.

Mary Glowacki, an archaeologist and president of the Pre-Columbian Archaeological Research Group, called the paper "thought-provoking" but noted that "most early Andean societies used intoxicating substances — including vilca — for political negotiation." She questioned whether the Wari's use of psychedelics was greatly different from that of other groups in the region.

Chimpanzees could be consuming the equivalent of a beer and half a day from eating alcoholic fruits, according to the first estimates of wild chimp alcohol intake.

By virtue of their fruit-filled diets alongside natural fermentation, chimps (Pan troglodytes) in Uganda and the Ivory Coast probably eat around 0.5 ounces (14 grams) of ethanol a day.

That doesn't mean the chimps are getting drunk. But it could mean that our predilection for alcohol comes from exposure to ethanol from fermented fruit in ancestral diets, according to research published Sept. 17 in the journal Science Advances.

"They're definitely not getting drunk," study co-author Aleksey Maro, a primatologist at University of California Berkeley (UC Berkeley), told Live Science. "If you had two drinks split through the whole day, you wouldn't feel much either."

The idea that humans have a taste for alcohol because it first appeared naturally in our diets is called the "drunken monkey hypothesis," and was proposed by study co-author Robert Dudley, a professor of integrative biology at UC Berkeley. Dudley's hypothesis postulates that there was a period of primate evolution during which our early ancestors couldn’t metabolize fermented fruits, and so were missing out on high calorie meals.

To tap into this nutritious resource, primates evolved to be able to hold their liquor by being able to break down ethanol.

However, until now scientists have only directly observed chimps eating fruit known to contain ethanol once, reporting chimps in Guinea-Bissau eating and sharing naturally-occurring fermented African breadfruit in 2022.

"I'm as skeptical as everyone else about the drunken monkey hypothesis," Maro said, "so I've taken care to do my own sleuthing."

To figure out how regularly chimpanzees could be consuming ethanol rich fruits, Maro and his team followed two groups of chimps: The Ngogo chimpanzees in Uganda and the Taï chimpanzees in Côte d'Ivoire. They observed the chimps for three periods lasting several months between 2017 and 2021.

The researchers took samples of freshly fallen fruit whenever they encountered them eating. From this, they retrieved 254 ripe fruit samples from 15 fruit species in Ngogo and 245 samples from six species in Taï.

To estimate the alcohol content in the samples, the team either analyzed the alcohol vapor found inside the fruit or used a chemical reagent that turned yellow on contact with ethanol.

They found that the Ngogo chimps ate fruit with an average ethanol concentration of 0.32%, meaning that there was 1.1 ounces (32 grams) of ethanol in every 3.5 ounces (100 grams) of the total weight. The fruit eaten by the Taï chimps had a remarkably similar average ethanol concentration at 0.31%.

Maro and his team then used pre-existing data on chimp diets and body weights to estimate the chimpanzees' daily ethanol intake across the two populations. They found that both male and female chimps consume approximately 0.5 ounces ethanol per day, which is around 2.5 standard drinks when adjusted for their smaller body size.

Matthew Carrigan, a molecular biologist at the College of Central Florida who was not involved in the research, said that while the results aren't necessarily surprising, they are exciting because it's moving forward an "important question about human ethanol addiction and evolution."

However, Carrigan pointed out that "there's a very wide range" in the error bars, meaning that the chimps could be eating as little as 0.14 ounces (4 grams) of ethanol per day, or as much as 0.85 ounces (24 grams) — the difference between less than one drink or four.

Maro also acknowledged that the research samples could have been fruits the chimps refused to eat. The next step is to investigate if the chimps are opting to avoid or seek out individual fruits based on their degree of fermentation, Carrigan said.

Ultimately, humans and chimpanzees "evolved to get calories without getting drunk," Carrigan said. "Otherwise, if we evolved to get drunk, then we would not evolve to metabolize the ethanol faster."

Chemists have synthesized a "super alcohol" previously thought to be too unstable to exist. The molecule was formed under extreme, "space-like" conditions and may shed light on the complex reactions required to form extraterrestrial life.

The super alcohol is called methanetetrol and is the only alcohol with four oxygen and hydrogen groups around a single carbon atom. It is thought to be a key building block for life in the universe. "This work pushes the boundaries of what we know about chemistry in space," study co-author Ralf Kaiser, a chemist at the University of Hawaii, said in a statement.

Methanetetrol is a type of ortho acid, a class of compounds thought to be critical in the chemistry of early life. However, these compounds are hard to isolate and study. Methanetetrol's high number of oxygen bonds, for example, make it very unstable and likely to break down if not kept in specific environmental conditions.

Methanetetrol doesn't occur naturally on Earth, but scientists have theorized about its existence and chemical structure for more than a century, according to the statement.

To emulate how methanetetrol might form in space, the researchers put water and carbon dioxide in a minus 451 degree Fahrenheit (minus 268 degrees Celsius) cryocooler, and then exposed the mixture to cosmic ray-like radiation to trigger the necessary chemical reactions to bring these molecules together.

Using ultraviolet light, the team then detected small amounts of the super alcohol in a gaseous form. They revealed their findings in a study published July 14 in the journal Nature Communications.

Related: Why is alcohol used to preserve things?

This work "pushes experimental and detection capabilities to the 'final frontier, the next level beyond what could be accomplished before due to the lack of experimental and computational approaches," Kaiser said in another statement.

"A prebiotic bomb"

Now that they are able to study methanetetrol, astrobiologists can learn how this alcohol is synthesized and reacts with other molecules in the coldest parts of space, such as the dust clouds where stars and planets form.

"You have this compact, carbon-oxygen molecule that just really wants to go 'boom,'" study co-author Ryan Fortenberry, an astrochemist at the University of Mississippi, said in the statement. "And when it does, when you give it any kind of energy, you'll have water, hydrogen peroxide and a number of other potential compounds that are important for life."

Methanetetrol is like "a seed of life molecule," he explained, that could be a building block of life across the universe. "It's something that can lead to more complex chemistry if given the opportunity."

Fortenberry likened the alcohol to an acorn, which can't grow into a tree on its own, but requires the right conditions and reactions to do so. "It's like a prebiotic bomb," he said.

The chemists concluded that, because it can form in the space-like conditions of a lab, methanetetrol can also form in space. "If we can find places where methanetetrol forms naturally, we know that it is a place that has the potential building blocks to support life," Fortenberry said.

Researchers have found alcohol in the orbit of a young star, and it could help them understand the origins of life on Earth.

Methanol (methyl alcohol) and its isotopes (versions of elements) were detected in gases around a star called HD 100453, which is about 330 light-years from Earth. This is the first time researchers have found isotopes of methanol in the disk of a young star like HD 100453, the scientists reported in a study published June 5 in The Astrophysical Journal Letters.

Methanol is a building block for organic compounds such as amino acids, which are needed for life. Researchers had previously detected methanol — but not its far rarer isotopes — in other star-forming disks.

"Finding these isotopes of methanol gives essential insight into the history of ingredients necessary to build life here on Earth," study lead author Alice Booth, a research fellow at the Harvard and Smithsonian Center for Astrophysics, said in a statement.

Related: A hidden 'super-Earth' exoplanet is dipping in and out of its habitable zone

Many young stars are surrounded by swirling disks of gas and dust. These protoplanetary disks, also known as planet-forming disks, provide the material for planets, moons and comets to form.

The team made the methanol discovery using data from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. ALMA maps the chemical composition and distribution of gas in nearby (relatively speaking) protoplanetary disks.

HD 100453 is larger than the sun, with about 1.6 times the sun's mass. This means that methanol and other molecules in its disk exist as a gas farther from their home star than would have been the case when our solar system was young. Smaller stars have cooler disks, so their molecules are normally frozen as ice and undetectable to ALMA, according to the statement.

In HD 100453's disk, the researchers found that the ratio of methanol to other organic molecules was similar to that of comets in our solar system. The findings suggest that ices within protoplanetary disks eventually clump together to form comets loaded with complex organic molecules, which may then be delivered to planets through collisions.

"This research supports the idea that comets may have played a big role in delivering important organic material to the Earth billions of years ago," study co-author Milou Temmink, a doctoral candidate who studies protoplanetary disks at Leiden University in the Netherlands, said in the statement. "They may be the reason why life, including us, was able to form here."

The brain might have a hidden "off switch" for binge drinking, and it seems to be governed by fewer than 500 brain cells, new research suggests.

The study, published June 10 in the journal Nature Neuroscience, found that in mice, activating or blocking this unique cluster of brain cells, or neurons, can suppress or unleash binge drinking.

If the same "off switch" can be found in humans, this tiny neural circuit could become a new target for the treatment of alcohol use disorder.

"What we have learned over the past five to 10 years is that the diversity [of the brain] is absolutely staggering, and it doesn't take many neurons to control behaviors," lead author Gilles Martin, an associate professor of neurobiology at UMass Chan Medical School, told Live Science. "This study seems to really agree with that."

A brake in the brain

For the past decade, scientists have suspected that the medial orbitofrontal cortex — a brain region that helps weigh whether a reward is worth its negative consequences — has been involved in binge drinking. But until now, they didn't have the technical know-how to understand what was going on inside this region.

Now, using new mice that had been genetically engineered to have the molecular equivalent of a genetic light switch, Martin and his colleagues looked for hidden structures inside this complex web of neurons.

The team used optogenetics — a technique in which light stimulation can be used to switch certain genes on or off — to identify in real time which brain cells lit up in response to alcohol consumption. They could then excite or suppress that region of the brain to see how it affected the mice's behavior.

The researchers found that a tiny cluster, made up of about 4% of the medial orbitofrontal cortex, lit up when the mice drank alcohol.

Related: What counts as 'binge drinking'? What about 'high-intensity drinking'?

When the scientists switched off that cluster, the mice's drinking went "up and up and up" every week, Martin said. When those neurons were switched on, the mice drank a lot less. This suggests the cluster acts as a "built-in brake mechanism that was previously unknown," he added.

The manipulation of this cluster did not seem to affect other behaviors, and the study showed it didn't change how much water the mice drank or how much they moved around, Martin said.

"I think it's the first instance where a drug of abuse turns on a bunch of neurons that will actually counter its effects," Martin said.

More research is needed to see whether humans also have such an off switch. But if confirmed, these findings could help explain why some people have a harder time resisting binge drinking than others: This brain circuit could be less active in them.

"If people don't have these aversive negative cues, this can promote excessive alcohol drinking," David Werner, an associate professor of psychology who studies the neurobiology of alcohol use at Binghamton University in New York and was not involved in the study, told Live Science.

Further research on this "unique" subset of neurons, Werner added, could reveal new treatment targets.

Surprising findings

The fact that these off-switch neurons were found in the prefrontal cortex was the most surprising finding of all, Martin said. Past studies have shown that these inhibitory neurons, which create aversions to certain behaviors or experiences, were usually found in other brain regions.

It will be interesting to see what is happening in people who binge drink repeatedly over a long period, Martin said, as the study did not investigate what happens after long-term stimulation.

Another surprise was that this cluster of neurons also seems to be alcohol-specific. In the study, the activation of the cluster did not change the mice's consumption of saccharine — which is essentially sugar, another stimulant with a strong reward feedback loop, Martin said.

"My hunch is now that each drug will probably activate a very distinct neuronal ensemble," Martin said.

Werner noted that alcohol has "a number of targets" in the human brain. For him, it will be very interesting to examine how this cluster fits into the picture of alcohol use disorder that includes all of these brain regions.

"What is going to cause one person to have alcohol use disorder is not going to work for the next," Werner speculated.

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.

Beer is one of the most popular beverages in the world, with nearly every country having its own local lager. In the U.S. alone, the overall beer market in 2023 totaled $116.9 billion, and breweries shipped out 192 million barrels of beer.

But the ice-cold, bubbly beverage we know today didn't always exist. So when was beer invented?

The answer traces back thousands of years. But there's still some mystery surrounding the exact origins of beer, and the beer of ancient times probably didn't taste anything like what you're used to today.

"We don't actually know exactly how [beer] was discovered," Tate Paulette, an associate professor of history at North Carolina State University, told Live Science. "Partly because of the kind of evidence we have, it's unlikely that we're going to get that kind of answer."

Because humans discovered fermentation so long ago, it's difficult to find evidence of exactly where beer-making began, Paulette explained. Much of the evidence comes from organic-residue analysis, he said.

Using this technique, archaeologists can identify the chemical signatures of grain fermentation on ancient ceramic or stone vessels. Researchers have found strong evidence of beer brewing as far back as the Neolithic period (10,000 to 4,000 years ago), when agriculture took root, in sites all around the world.

The oldest beer

Kirk French, an assistant professor of anthropology at Penn State, pointed to 9,000-year-old sites in China as the best evidence for ancient beer brewing. At the Qiaotou archaeological site in southeastern China, archaeologists found residues of plants, yeast and mold on ancient pots near human skeletons, suggesting that they once contained a beer-like fermented beverage. Analyses indicate that the beverage those pots contained also included rice, tubers and fungi.

Another site in China from the same time period, Jiahu, also contains bronze vessels with chemical signatures of grain fermentation, as well as residues of rice, honey and fruit.

French said the Jiahu site contains the most foolproof evidence of ancient beer because the chemical residues were found in drinking vessels. There are even older potential instances of beer brewing, but the evidence isn't as strong. That's because analyses of the older sites rely on residues found on cookware, which also could have been used to make bread or porridge; both foods involve a small amount of fermentation and can leave the same chemical signatures as beer brewing.

Related: Why is alcohol used to preserve things?

One of these older sites is an 11,000-year-old cultic feasting location in Turkey. At the site, named Göbekli Tepe, researchers found large stone kilns with residues of ground grain. Although these kilns also could have been used to grind grain for bread, one of the researchers argues that the finish on the stone suggests the grain was ground coarsely, in a manner more appropriate for fermenting beer or making porridge than for baking bread.

Some archaeologists have proposed that beer dates back even earlier, to a 13,000-year-old cave near Haifa, Israel. There, researchers found starch granules in pits taken out of the bedrock that could indicate fermentation. But again, it's possible these stone pits were used for making food rather than drinks.

"It's totally possible (and maybe even likely) that they were making beer," French told Live Science in an email. But ultimately, he said the evidence is too ambiguous to make a conclusion.

Paulette said we likely will never know the exact date that humans brewed their first batch of beer, though emerging evidence continues to push the potential date back further and further. Both experts agreed it's unlikely that beer was "invented" in one place and spread from there; rather, fermentation was probably independently discovered by different groups of people throughout the world.

What did ancient beer taste like?

Though it's still a mystery exactly when and where the first beer was made, one thing is clear: Ancient beer would have tasted quite different from a modern lager.

For one, it would have been sour — a flavor resulting from both yeast and lactic acid bacteria fermenting the grain, Paulette said. It also may have been thick and unfiltered. That's because the process of ancient beer brewing began with a mixture of ground grain and water, and the remaining sediment wasn't always filtered out after fermentation. Paulette said there is some written evidence of "strained" beer in Mesopotamia. But more often than not, imagery and artifacts from the period show that people drank beer through straws with filter tips, suggesting that the beer itself was unfiltered.

In ancient times, beer was also likely drunk shortly after it fermented; otherwise, it could quickly go bad and develop harmful mold or bacteria. Because of this, ancient beer was likely relatively flat and not particularly high in alcohol, unlike our bubbly, boozy IPAs. And without refrigeration technologies, beer was definitely not ice-cold.

French said the beers we know and love today are only about 500 years old.

"They really start in the 1500s, with the Czech beers and German beers," he explained. This is when lagering — the process of cold-fermenting beers that creates a clear, crisp and bubbly beverage — was developed. As Germans migrated around the world in the coming centuries, they brought this brewing technique with them.

"That's why, if you've traveled a lot, it doesn't matter where you go in the world — you can find your basic lager," French said.

Chimps have been spotted sharing alcoholic food for the first time, hinting that ancient ape behaviors gave rise to social drinking in humans.

Researchers filmed the boozing chimpanzees (Pan troglodytes) gorging on fermented fruit in West Africa as part of a new study exploring alcohol consumption in one of our closest living relatives. The footage is the first evidence that nonhuman great apes consume alcohol together, supporting the idea that social aspects of consuming alcohol are deeply rooted in the ape family tree.

Humans have a history of gathering together to eat, drink and be merry. This feasting behavior has a number of social benefits and can help boost social bonds — though drinking alcohol also carries health risks. Now, the footage of chimps sharing fermented fruits has left researchers wondering whether chimps get similar social benefits from consuming alcohol in a group.

"Chimps don’t share food all the time, so this behaviour with fermented fruit might be important," study co-author Kimberley Hockings, an associate professor in conservation science at the University of Exeter in the U.K., said in a statement. "We need to find out more about whether they deliberately seek out ethanolic [alcoholic] fruits and how they metabolise it, but this behaviour could be the early evolutionary stages of 'feasting'."

The researchers published their findings Monday (April 21) in the journal Current Biology.

Related: 'Contagious' peeing may have deep evolutionary roots, chimp study suggests

Alcohol consumption is likely common in the natural world. Lots of wild foods, including fruit, sap and nectar, contain the kind of alcohol humans put in drinks (ethanol) and thus will be ingested by many animals, including primates.

Humans have been producing and drinking alcoholic beverages for around 9,000 years. However, our ancestors — and the ancestors of chimps — developed an enhanced ability to metabolize alcohol around 10 million years ago. This adaptation suggests that alcohol consumption is an ancient ape behavior.

To learn more about how chimpanzees consume alcohol, the researchers observed chimps eating naturally fermenting fruit from African breadfruit trees (Treculia africana) in the Cantanhez National Park in Guinea-Bissau. The team used camera traps to film the chimps eating and analyzed the alcohol content in the fruit.

The researchers observed the chimps sharing African breadfruit on 10 separate occasions and found that 90% of this shared fruit contained alcohol. The alcohol content wasn't high by human standards, with a maximum of 0.61% alcohol by volume (ABV) — a beer is usually around 5% ABV. However, the impact of alcohol on a chimp's metabolism is unknown, and they might not need as much as we do to feel a buzz.

A chimp's diet can be up to 85% fruit, so if plenty of that is fermented, then they may be consuming significant amounts of alcohol. That said, the researchers noted that the chimps probably aren't getting drunk, as that would be detrimental to their survival chances, according to the statement.

The study also highlighted that chimps gain benefits from consuming fermented fruit that have nothing to do with alcohol consumption. For example, the exterior of fermented fruit is softer than less ripened fruit, so chimps find it easier to open and eat.

While the researchers said their study supports the idea that alcohol consumption is rooted in ape evolutionary history, they noted that more work is needed to fully understand the social side of alcohol consumption.

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.

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.

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.

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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."

Archaeologists in Spain have discovered the world's oldest known liquid wine in an unexpected place: mixed with ashes inside a Roman-era funerary urn, a new study finds. 

The wine, which the scientists described as "reddish liquid" in appearance, was found in a roughly 2,000-year-old tomb during a house construction project in Carmona, a town in Seville, in 2019.

The use of wine in Roman-era burial rituals is well documented, but discovering a wine sample this old, in its liquid state, was "rather exceptional and unexpected," the scientists wrote in their paper, published June 16 in the Journal of Archaeological Science: Reports. 

"It's a sunken tomb that was excavated from the rock, which allowed it to remain standing for 2,000 years," José Rafael Ruiz Arrebola, an organic chemist at the University of Córdoba and a senior author of the study, told The Guardian. 

Wine contains distinct chemical compounds that reflect not only its flavor and appearance but also its origins. But after many years, these chemicals often undergo substantial decay that makes them difficult to characterize, the scientists wrote in the paper. 

During the funerary ritual, cremated ashes were mixed with the liquid, making it murky, the scientists told The Guardian. 

Using analytical techniques including high-performance liquid chromatography and mass spectrometry, the scientists sifted through element-by-element to find components that belonged to the liquid. 

Wine grapes contain distinct plant compounds known as polyphenols that serve as a "barcode," marking their varietal and the conditions in which they were grown and harvested. However, "few studies have been conducted on polyphenols in archaeological wine remains," the scientists wrote in the study. 

When the scientists found polyphenols in the liquid sample, their suspicions were confirmed — the ancient liquid was indeed wine.

From looking at historical texts, they suspected that the wine would have been similar to modern fino wines produced from regions in southern Spain. The scientists compared the polyphenol content of the ancient wine to today's wines to determine that the wine was likely from Doña Mencía, a city in southern Cordoba.

While the liquid is reddish, it lacked syringic acid, a compound that is produced by red wine when it decomposes, which confirmed that the original wine was actually white. 

Despite having mostly decayed, the ancient wine isn't, "the least bit toxic," according to microbiological analyses, Arrebola told The Guardian. Nevertheless, the scientists did not taste it.

Other ancient wine analyses have focused on dried remnants, such as the 8,000-year-old fingerprints of tartaric acid, a compound of grapes and wine, found on a clay jug in the Republic of Georgia. Because the new study analyzed liquid wine, this discovery is one of a kind.

"We have been lucky to find it and analyze it — it's something you only see once in your life," Arrebola told CNN.

A woman kept ending up in the emergency room with excessive sleepiness, slurred speech and the scent of alcohol on her breath, but she had not ingested a drop of liquor. It turns out that microbes in her gut were brewing their own booze — and making her drunk.

Doctors eventually diagnosed her with a rare condition called auto-brewery syndrome. But before that, the 50-year-old had been referred to emergency departments seven times over the course of two years. Each time, her symptoms were similar and made her seem drunk. Her sleepiness, in particular, was troubling, as she'd suddenly fall asleep while getting ready for work or preparing meals. This drowsiness would keep her out of work for weeks and suppress her appetite.

During each visit to the ER, expect the last, doctors diagnosed her with alcohol intoxication. However, "in recent years, she had stopped drinking altogether because of her religious beliefs," doctors wrote in a new report of her case, published Monday (June 3) in the Canadian Medical Association Journal. Her family confirmed that she didn't drink.

Eventually, doctors discovered that the patient's medical history held a clue as to what was causing these bouts of drunkenness.

Related: Can you be intolerant to alcohol?

Prior to having these drunken episodes, the woman had a five-year history of recurrent urinary tract infections (UTIs), which come back repeatedly and are very difficult to prevent. To treat these, she was prescribed frequent courses of antibiotics, one after the other. 

The woman's doctors suspected that, in addition to clearing her UTIs, these heavy doses of antibiotics wiped out helpful bacteria in her gut. This likely cleared the way for various fungi in the gut to take over. Some of these fungi can ferment carbohydrates, essentially brewing their own alcohol. 

Auto-brewery syndrome arises when such fungi — including Saccharomyces cerevisiae, or brewer's yeast, and Candida albicans — grow in high enough concentrations and access enough carbs through a person's diet to intoxicate them. Some bacteria have also been tied to the syndrome. People with high blood sugar and a poor ability to break down alcohol are thought to be more prone to the disorder, and these characteristics partly come down to genetics.

It can be difficult to get a diagnosis for auto-brewery syndrome, as it's very rare. Fewer than 100 cases have been reported since its discovery in the late 1940s.

In the woman's case, before being diagnosed with the condition, she was assessed several times by psychiatrists in the ER for signs of alcohol use disorder. However, none of these assessments pointed to signs of addiction. At her seventh ER visit, a doctor suggested that auto-brewery syndrome might be a possibility and started her on a course of antifungal medication. After being referred to a gastroenterology clinic, she was also placed on a low-carb diet to deprive the fungi of sugar to ferment.

After her symptoms went away for several months, the patient upped her carb intake, and symptoms of drunkenness returned. Again, antifungal drugs and a low-carb diet eliminated the symptoms.

The patient was also given probiotics to help restore the helpful bacteria in her gut, and her primary care doctor was advised to give her narrow-spectrum antibiotics for UTIs. Broad-spectrum antibiotics kill many bacteria at once and thus can have a huge effect on the gut microbiome. Narrow-spectrum antibiotics, on the other hand, are much more targeted and can be tailored to the bacteria likely causing the infection.

After the patient went months with no relapses, the doctors tested whether her eating carbs would increase the alcohol levels in her blood. Finding that it didn't, they advised the patient to slowly increase her carb intake, while being monitored by her clinical team.

"Auto-brewery syndrome carries substantial social, legal, and medical consequences for patients and their loved ones," the doctors wrote in the case report. "Our patient had several ED visits, was assessed by internists and psychiatrists, and was certified under the Mental Health Act before receiving a diagnosis of auto-brewery syndrome, reinforcing how awareness of this syndrome is essential for clinical diagnosis and management."

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! 

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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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.

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!

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!

A new gene therapy that "resets" the brain's reward system could help treat alcohol use disorder, a new study in monkeys suggests. 

In monkeys who tend to drink heavily when provided lots of alcohol, surgically injecting a gene therapy into the brain increased the production of the so-called feel-good hormone dopamine, the study showed. This, in turn, dramatically reduced the primates' alcohol consumption, the effects of which were sustained over a year. 

If safe and effective in humans, the therapy could provide a "one-time" treatment for alcohol use disorder (AUD), a medical condition in which patients can't stop or control their drinking despite it negatively impacting their daily life. Excessive drinking causes 140,000 deaths a year in the U.S., and although AUD is one of the most common psychiatric disorders, only three drugs for it have been approved by the U.S. Food and Drug Administration (FDA). 

None directly target the underlying brain changes seen with sustained heavy drinking. 

Related: What does alcohol do to the body?

Alcohol boosts the brain's production of dopamine, which leads to feelings of relaxation and improved mood. However, in AUD, the brain adapts by producing less dopamine on its own, meaning people need to drink more to achieve the same positive effects.  

That's also true in monkeys that drink heavily, even during periods when they aren't consuming any alcohol, study lead author Kathleen Grant, a professor of behavioral neuroscience at Oregon Health & Science University, told Live Science.  

In the new study, published Monday (Aug. 14) in the journal Nature Medicine, Grant's team injected a genetically modified virus into the ventral tegmental area — a region in the brain involved in reward processing — of four monkeys as part of a surgical procedure. Those monkeys had been given access to increasingly higher amounts of ethanol dissolved in water over several months to the point where their consumption levels simulated chronic alcohol binge drinking in humans. 

Using a similar approach to what has already been used to treat Parkinson's disease and a rare genetic disorder known as aromatic L-amino acid decarboxylase deficiency, the harmless virus carried a gene that encodes the protein glial cell line-derived neurotrophic factor (GDNF), which helps preserve and regrow neurons. By putting the GDNF gene into cells that make dopamine, the team assumed it would spur them to produce normal levels of the chemical. 

The monkeys reduced their alcohol consumption by more than 90% compared with controls, and their dopamine levels were restored to "normal levels" for at least a year after treatment, roughly equivalent to nine to 12 years in human time, Grant said. Because relapse is such an "integral part of the cycle" of AUD, getting back to levels the animals had before they started drinking heavily is crucial, she emphasized. 

Andrew Mcquillin, a professor of molecular psychiatry at University College London who was not involved in the research, told Live Science in an email that the long-term side effects of this treatment are still unclear. Although brain surgery is "generally well-tolerated" in humans, he said it "seems a somewhat invasive approach for all but the most severe cases of alcohol use disorder."

Grant also urged caution in over-generalizing the findings. "This is only proof-of-principle that it is possible to reverse this behavior in people with drinking disorders that are resistant to all other treatments," she said. "This would not be your first line of treatment, [it] would be appropriate only for very severe cases of alcohol use disorder."

Mcquillin added that future studies will be needed to test the acceptability of this treatment for substance use disorders. The findings could, however, open doors for other treatment options. 

"There is also the possibility that new or existing small molecules that mimic the therapeutic mechanism in this study may represent new treatment targets for substance use disorders," he said.

From its humble medieval origins as a medicinal agent, vodka has conquered the world. In 2020, the worldwide sales of vodka earned around $45 billion, and U.S. consumers alone guzzled 189.7 million gallons (862.4 million liters) of the potent alcoholic beverage, according to Beverage Dynamics, a national magazine focused on retail alcohol sales. 

But what is vodka made from?

To produce vodka, you must first ferment any foodstuff that contains sugar or starch, then distill the product to increase its alcohol content. (Fermentation means feeding sugar to yeast, so that the yeast can produce alcohol.) Vodka can made from fermented grains such as sorghum, corn, rice, rye or wheat, tor from potatoes, sugar beet molasses or even fruit, according to "Vodka: A Global History," (Reaktion Books, 2012).

The fermentation step creates a product with only about 16% alcohol by volume (ABV) — too low for spirits. Upping that number requires distillation, or heating in a  container known as a still. Alcohol's boiling temperature is lower than that of water, which means the alcohol evaporates and can be collected separately from the water. Most vodka is 30% to 40% ABV. "Rectified spirits," like the American brand Everclear, reach 95% ABV.

Related: Why is fermentation used to preserve things?

The first records of a distilled vodka-like spirit come from Islamic alchemist and chemist Jabir ibn Hayyan, who invented a distilling device to capture the vapor from heated wine for scientific purposes, according to "Vodka: How a Colorless, Odorless, Flavorless Spirit Conquered America," (Lyons Press, 2014). Vodka reached Russia by the 1430s century, when a monk named Isidore adapted the Italian drink aqua vitae, according to the book. This first vodka likely smelled bad, tasted even worse, and was used mainly for medicinal purposes.

Over the course of a few centuries, distillers got better at their practice, the flavor improved, and "voda" eventually became the preferred beverage of the Russian empire, according to the book. 

Vodka's popularity spread with Russian Soldiers, gaining a foothold across Europe during the Napoleonic Wars. In the 1860s, former serf Pyotr Smirnov perfected the distillation process and began selling something that resembled the odorless, clear beverage familiar today.  Following the civil war that established the Soviet Union, Smirnov's son Vladimir moved the distillery to Paris and used a French spelling of his name: Smirnoff, according to the book.

Originally published on Live Science.

If you've ever visited a laboratory or museum and admired a pristine eyeball or a tiny deceased critter floating in a glass jar, you've seen the preservation power of alcohol. The formal name of this technique is fluid preservation. Scientists have been relying on it since the 1600s to preserve their curious specimens. And, if done correctly, it can sustain a sample for hundreds of years, according to the American Museum of Natural History. 

But, how does it work? 

"The long and the short of it is that it's toxic to the kinds of microorganisms that would cause decay," Bill Carroll, an adjunct professor of chemistry at Indiana University Bloomington, told Live Science. He used wine as an example. It's made as yeast eats sugar from grapes and then excretes alcohol. But the yeast excrete so much alcohol that the concentration becomes toxic and kills the yeast, he said. And that alcohol content — around 14% — helps delay the growth of bacteria for years (many wines also contain additional preservatives like sulfur), according to the California Wine Advisor. 

Related: Does salt make water boil faster?

Preserving other organic material — such as DNA, tissues or even entire animals — requires a higher alcohol concentration, said Katherine Maslenikov, the fish collections manager at the Burke Museum in Seattle. Maslenikov typically relies on alcohol, specifically ethanol, for long-term storage. 

For example, Maslenikov might take a fish specimen, remove some tissue samples for DNA analysis and inject the fish with formalin (a solution of formaldehyde gas dissolved in water) to stop the internal biological processes, such as enzymatic reactions and tissue degradation. Then, she might immerse the fish specimen in a jar of 70% alcohol, 30% water. For long-term storage, "70% seems to be that magic number," Maslenikov said. There's enough water in the solution that the tissues will stay hydrated, which helps the animal or specimen hold its shape, and there's enough alcohol to prevent mold and bacterial growth, she said.

Alcohol at even higher concentrations, for instance 95% ethanol, works as a dehydrant, meaning it removes and replaces the water in the cell, tissue or whole-body specimen with alcohol. The lack of water causes changes to water-sensitive proteins; they unfold, or denature, and harden in place next to one another, fixing the specimen's shape, according to Ask a Biologist, a series run by Arkansas State University. This technique is a common way of preserving DNA, according to a 2013 study in the journal PLOS One.

It can be tricky deciding what percentage of alcohol to use. Using too much or too little can affect the sample's shape and flexibility, or even lower its ability to preserve the sample in the solution. High concentrations of alcohol used to dehydrate a specimen will preserve it. But Maslenikov said this process can also leave a specimen shriveled (from the loss of water) and brittle (from the hardened proteins). Sometimes that's OK; it all depends on what you are trying to preserve. 

Meanwhile, a specimen might deteriorate quickly if it retains too much water.

"If an organism has enough water in its tissues, it can dilute the alcohol," Christopher Rogers, an associate research professor at the Kansas Biological Survey and Center for Ecological Research at the University of Kansas, told Live Science in an email. If this happens, the alcohol concentration might not be potent enough to kill lurking microorganisms that might be harbored deeper in the specimen, somewhere like the gut of a whole-animal specimen. Those missed bacteria can decompose the specimen. "This is why it is important to change the alcohol [about] 24 hours after pickling the critter," because it boosts the solution's alcohol concentration, Rogers said. 

When it comes to using alcohol as a preservative, Carrol said you're looking for a concentration sweet spot: "A concentration such that you inhibit microorganisms, but not destroy the cell structure of what you're looking at."

Originally published on Live Science.

In 2019, a group of scientists and distillers decided to create a bold new type of booze: Atomik, an artisanal alcoholic spirit made from ingredients grown in the Chernobyl nuclear power plant's still-radioactive exclusion zone. (The booze itself was not radioactive after the distilling process, Live Science previously reported).

Now, the first batch of Atomik is finally complete — and all 1,500 bottles of it have been seized by Ukrainian Secret Services agents for unknown reasons, according to a statement from Atomik's manufacturer, The Chernobyl Spirit Company.

"It seems that they are accusing us of using forged Ukrainian excise stamps, but this doesn't make sense since the bottles are for the U.K. market and are clearly labelled with valid U.K. excise stamps," Jim Smith, founder of the company and a professor at the University of Portsmouth in the U.K., said in the statement.

Related: 5 weird things you didn't know about Chernobyl

Elina Smirnova, a lawyer representing the company, added that the seizure was a "clear violation" of Ukrainian law. If Atomik does make its way onto shelves, it will be the first consumer product from the Chernobyl region since the infamous 1986 meltdown, the company said.

Soon after the nuclear disaster, officials deemed the Chernobyl exclusion zone — the 1,000-square-mile (2,600 square kilometers) area surrounding the damaged power plant — uninhabitable by humans for 24,000 years. However, plants and animals are now thriving in the region — and so is tourism. According to local tourism officials, Chernobyl sees upwards of 60,000 visitors a year, with visits spiking after the May 2019 debut of HBO's "Chernobyl" miniseries.

Atomik is made from apples grown in Ukraine's Narodychi District, which sits on the edge of the exclusion zone and was heavily polluted by fallout from the meltdown. This region still has a population of nearly 10,000 people, according to Ukraine's State Statistics Service, and must abide by stringent agricultural restrictions.

With Atomik, Smith and his colleagues hope to prove that some products made near  the exclusion zone can be safe for consumption, according to the company's website. Several years ago, the Atomik team tested rye crops from the exclusion zone for radiation, and found that the grains were indeed contaminated. However, Smith said, all traces of radiation were removed during the distillation process, making Atomik no more dangerous than other commercially available spirits.

Since then, the founders have changed their recipe from a rye-based booze to an apple-based one — but, according to Smith, the distillation process still renders the final product completely radiation-free. If Atomik makes it to liquor shops, 75% of the company's profits will be used "to help bring jobs and investment to the Chernobyl affected areas of Ukraine and to further support the community," according to the company's statement.

In the meantime, would you care to try a bottle of wine exposed to cosmic radiation aboard a space station for 14 months? It'll only cost you $1 million.

Originally published on Live Science.

When you pour a glass of beer, a frothy cascade of fizz rises to the top; as more and more tiny bubbles coalesce, they form a nose-tickling layer of foam. 

At first, that frothy stream of carbonation seems endless. But just how many bubbles can emerge from a glass of beer before it goes flat?

Gérard Liger-Belair, a professor of chemical physics at the University of Reims Champagne-Ardenne in France, had previously explored this effervescent subject in Champagne, calculating that one flute produces about 1 million bubbles. Recently, Liger-Belair peered into the depths of beer glasses and found that they produce twice as many bubbles as Champagne — with up to 2 million bubbles popping in a half-pint glass, according to a new study. 

Related: When was beer invented?

Archaeological evidence shows that people have been brewing and drinking beer for at least 5,000 years and possibly for as long as 13,000 years, Liger-Belair and co-author Clara Cilindre, an associate professor and researcher in the Molecular and Atmospheric Spectroscopy Group (GSMA) at the University of Reims, reported in the study. The beverage "is by far the most popular alcoholic drink worldwide," with global production reaching nearly 53 billion gallons (200 billion liters) per year, and bubbles and foam are an important part of the beer experience, Liger-Belair told Live Science in an email. This is especially true of lager, the most popular type of beer, Liger-Belair said.

"It seems pertinent to us to bring some more knowledge about bubble formation, bubble size and finally about the issue of the total number of bubbles likely to form in a glass of beer along the entire natural degassing process," he said.

Beer is typically made of four ingredients — malted cereal grains, hops, yeast and water — which are then fermented. This process breaks down carbohydrates to produce alcohol, sugars and carbon dioxide (CO2). When beer is bottled or canned, additional CO2 is added, creating pressure in the container. Once the seal on a can or bottle is broken, the liquid becomes supersaturated with CO2, which is then released as tiny bubbles.

For the study, the researchers looked at beer that was 5% alcohol by volume, pouring about 8 ounces (250 milliliters) of beer at a temperature of 42 degrees Fahrenheit (6 degrees Celsius) into 17-ounce (500 ml) glasses. The scientists determined that the overall number of beer bubbles would be mostly affected by three factors: concentration of dissolved CO2 in the glass, volume of the bubbles, and the point at which beer becomes so CO2-depleted that no more bubbles can form.

Tiny flaws in beer glasses also help CO2 bubbles emerge from the liquid, the study authors found. Dissolved CO2 would collect around pits and crevices larger than 1.4 micrometers wide, forming streams of bubbles. High-speed photography then showed the bubbles getting bigger as they rose, capturing even more CO2 from the beer. In total, a glass of beer of this volume would generate between 200,000 and 2 million bubbles, according to the study.

However, this research wasn't just about counting bubbles, the scientists said. When bubbles in a beverage pop on a drinker's tongue, they enhance subtle flavors; by studying effervescence in liquid, scientists can learn how beverages behave under different conditions and how that can affect their taste, Liger-Belair said in the email. 

While the quantity of dissolved CO2 in beer is "a key parameter" for understanding this, the geometry of the glasses that hold the drink also plays an important part, "so that we can easily imagine modifying some beer and glass parameters for a better overall sensory experience," he said. 

"We believe that the beer industry could benefit from more knowledge about bubble science," Liger-Belair added.

The findings were published online March 31 in the journal ACS Omega.

Originally published on Live Science.

A oft-spoken piece of advice cautions those celebrating with a bottle of bubbly; allegedly, champagne makes you drunk faster than other beverages with similar alcohol content. But how much truth is there to this statement? In other words, do you need to exercise extra moderation with the champagne this Valentine's Day?

Although a typical glass of champagne has no more alcohol than wine, there is some evidence that it impairs people faster than its flat counterpart. But it's not just champagne that may have this effect, it's any alcoholic beverage with bubbles, said Hildegarde Heymann, a sensory scientist in the Department of Viticulture and Enology at the University of California, Davis. 

However, the jury is still out on whether alcoholic bubblies make drinkers tipsy faster than people downing still alcoholic beverages.

Related: Does drinking alcohol warm your body?

In a 2007 study, scientists met with 21 participants on three separate occasions, serving them a different drink each time. First, a glass of vodka, neat. Then, vodka mixed with still water. Finally, vodka mixed with an equivalent amount of carbonated water. Before each rendezvous, the participants fasted overnight. They had five minutes to drink the vodka — then, over the next four hours, the scientists measured their blood-alcohol concentrations using a breathalyzer test. 

The results of the study, published in the Journal of Forensic and Legal Medicine, appeared to confirm that sparkling alcoholic drinks really do make people drunk faster. On average, bubbly vodka spiked blood-alcohol concentrations faster than did the neat and the watered-down vodka. (Interestingly, both the bubbly and watered-down vodkas spiked blood-alcohol concentrations faster than the neat vodka, according to that same study. It's a phenomenon well-supported by other research. Blood-alcohol concentrations spike faster with beverages with alcohol concentrations of 10-20% — a cocktail or glass of wine, for instance. Stronger drinks seem to slow down alcohol's absorption into the bloodstream.)

But very few other studies to support this finding. The only other experiment to explore this question, published in 2003 in the journal Alcohol and Alcoholism included only 12 participants. Instead of comparing each participant's response to a still versus carbonated alcoholic drink, they sorted the participants into two groups: still wine drinkers and sparkling wine drinkers. The scientists did find that participants drinking sparkling wine absorbed more alcohol; but with so few in each group, the difference could have been due to natural variation in alcohol tolerance. 

Let's say that champagne does make us drunk faster. How would that work? It all comes down to how quickly alcohol moves through the digestive tract. While the stomach absorbs some alcohol, the intestines are far more efficient at shuttling the substance into our blood, Heymann said. So, the longer alcohol hangs out in the stomach, the less drunk you become. This process is controlled by the pyloric sphincter, a kind of gate that opens to let food exit into the intestines or closes to let it digest in the stomach. That's why it's a good idea to eat an appetizer with your champagne: "If you eat food with your alcohol, that slows down the process and you get less drunk," Heymann told Live Science. The sphincter closes to let the food digest. As a result, your blood absorbs the alcohol over a longer period of time, Heymann said. 

As for why spirits make us drunk less quickly than weaker drinks: scientists hypothesize that high alcohol concentrations irritate the lining of our stomach, causing it to produce mucus. Mimicking food, the mucus causes the pyloric sphincter to remain closed. 

Carbonation could trigger the pyloric sphincter to open sooner than it would otherwise, emptying the contents of the stomach into the intestines, Heymann said. There are some studies to suggest that carbonation does shorten the amount of time food and drink stays in the stomach. However, much of this research was conducted in the early-to-mid 20th century. More recent studies suggest that carbonated and flat beverages spend the same amount of time in the stomach.

So, if you're hoping to enjoy a glass of champagne on Valentine's Day, you probably don't need to worry about an extra bad hangover (as long as you're consuming in moderation, of course).  To act on the safe side, go ahead and pair your beverage with a bite to eat — maybe a box of chocolates.

Originally published on Live Science.

Young adults aren’t drinking as much as they used to. In fact, more than a quarter don’t drink alcohol at all, recent surveys show.

It’s good news for health. But there is also a downside in the data: While alcohol use is falling among 18-to-22-year-olds, marijuana use is inching upward. The number of young adults using both alcohol and marijuana is also rising, heightening concerns about a future surge in substance abuse problems, new research shows.

I am a professor of psychology at Texas State University who has been studying young adult and adolescent substance use for over 15 years. A key interest of mine is how substance use changes over adolescence and young adulthood. It is a period of profound change: A 13-year-old is very different from a 25-year-old in nearly every way.

With colleagues at the University of Michigan, the University of Central Florida and Iowa State University, I have been investigating trends in alcohol and marijuana use in young adults to better understand how use changes with age. The latest numbers offer both hope and concern.

Gen Z is breaking stereotypes

There are reasons for the stereotype of hard-drinking, substance-using young adults, as photos and videos from bars and college parties will attest. But surveys and our analysis suggest that binge drinking isn’t as common as people may believe it is.

Using data from the annual National Survey on Drug Use and Health, we found that in 2018 nearly 30% of college-age adults, ages 18-22, had not had a single alcoholic drink during the previous year, compared with fewer than a quarter in 2002. Over 60% had not used marijuana at all.

Among 18-to-25-year-olds, the number who reported binge drinking in the previous year fell from 39% in 2015 to 34% in 2019. That may be influenced at least in part by beliefs that are forming in high school. Another survey shows that nearly three-quarters of high school seniors think their friends would disapprove of weekend binge drinking, up from just over half in the early 1980s.

Adolescents – typically 12 to 17 years of age – were more likely to avoid both alcohol and marijuana than they were two decades ago, part of a larger trend in declining substance use and risky behavior among adolescents seen in a variety of national surveys and data sources. In 2019, nearly 80% of adolescents had not used alcohol at all in the previous year, compared with 65% in 2002, and 87% had not used marijuana.

Using both marijuana and alcohol

The bad news is that the number of college-age young adults saying they used marijuana at least once in the previous year has increased, from 33% to 37%.

The vast majority who said they used marijuana also used alcohol. We found that the increase in young adults using both was a result of young adults who used alcohol taking up marijuana, too.

This increase in using both alcohol and marijuana is an important warning sign, because young adults in that group also had much higher rates of other illicit drug use, like cocaine, and prescription drug misuse, involving medications like opioids or benzodiazepines.

That may signal that a greater number will need substance use treatment in the coming years.

Why the changes?

One theory for the shifting trends in alcohol and marijuana use is that adolescent substance use is now starting at later ages.

The data support this: The numbers of adolescents starting alcohol use has declined somewhat, while more college-age adults are first-time alcohol and marijuana users. Why that shift is occurring is less clear, but one theory is that adolescents have been engaging in more virtual contact than face-to-face contact in recent years and they rarely use substances when they’re alone.

Changing regulations likely also play a role. Marijuana is now legal for medical or recreational use in an increasing number of states.

Attitudes toward alcohol and marijuana have also changed over the years, particularly for marijuana.

The Monitoring the Future study, which has tracked substance use in adolescents and young adults since 1975, indicates both a sharp decline in disapproval of marijuana among middle and high school students and a decline in how harmful they perceive marijuana to be. In fact, more young people in that age group now see more harm from regular alcohol use than disapprove of marijuana.

[Deep knowledge, daily. Sign up for The Conversation’s newsletter.]

How the pandemic will change young people’s habits with alcohol and marijuana isn’t yet clear. One survey conducted this spring when many restaurants and bars were closed found that adults over 30 were drinking alcohol 14% more often. However, when researchers in Australia homed in on younger adults in Gen Z, they found a different story: Older age groups may be drinking more, but with bars and restaurants closed, 44% of the college-age crowd reported drinking less.

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

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook and Twitter. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

Though the COVID-19 pandemic has captured the country's attention, the U.S. has also been facing another deadly, but less visible, public health crisis. "Diseases of despair" or those related to substance abuse, alcohol dependency and suicidal thoughts and behaviors, have been surging in the U.S. over the past decade, according to a new study. 

Diagnosis of diseases of despair increased by 68% between 2009 and 2018 among a cohort of people studied in the U.S., according to a study published today (Nov. 9) in the journal BMJ Open. Strikingly, diagnoses related to suicide increased by 170% in that time frame, the authors found.

Previous research hinted that despair-related diseases were increasing across the U.S. but mainly focused on mortality.

Life expectancy  in the U.S. has declined steadily from 2015 to 2017, the longest sustained decline since about a century ago, and all-cause deaths among middle-age white people increased between 1999 and 2015, according to the study. Many of the premature deaths were "deaths of despair" such as suicides, overdoses and alcohol-related liver diseases.

Related: The drug talk: 7 new tips for today's parents

These trends coincide with decades of economic decline for less educated and unskilled workers, stagnant or falling wages and incomes, lower marriage rates and increases in single-parent households, and fewer people who are actively working or looking for work, according to the study.

"It is theorised that these changes have fostered growing feelings of despair, that is, disillusionment, precariousness and resignation," the authors wrote in the study. "Despair may in turn trigger emotional, cognitive, behavioural and even biological changes, increasing the likelihood of diseases that can progress and ultimately culminate in these deaths of despair."

In the current study, researchers analyzed the incidence of such diseases in 12 million people enrolled in health insurance plans between 2007 and 2018 through a large U.S.-based company called Highmark. The enrollees were concentrated in Pennsylvania, West Virginia and Delaware, three states that have been disproportionately affected by deaths of despair, according to a statement. They found that 515,830 of these people, or 1 in 20, were diagnosed with at least one disease of despair during that time period.

About 54% of those people were diagnosed with an alcohol-related disorder; over 44% with a substance-related disorder; over 16% with suicidal thoughts/behaviors; and a little under 13% with more than one disorder. Between 2009 and 2018, the rates of diagnoses of "diseases of despair" increased by 68%; the rate of alcohol-related diagnoses increased by 37%; substance related-diagnoses increased by 94%; and suicide-related diagnoses increased by 170%, according to the statement. 

People who were between 55 and 74 years old saw the largest increase in alcohol and substance abuse diagnoses, according to the study. Substance-related diagnoses in infants, from maternal drug abuse, increased by 114% across the study period. Suicide-related diagnoses increased by 287% among 1 to 17 year olds, by 210% among 18 to 34 year olds and 70% in everyone else.

Since the cohort enrolled with this insurance was concentrated in states with high prevalence of despair, the rates may not be as high everywhere in the U.S. Still, "increases in these conditions were found nationwide," said lead author Emily Brignone, a senior research data scientist at Highmark Health.

The study had several limitations. The data was drawn from people that filed insurance claims, "and the true rates of these conditions are likely even higher among those who are uninsured," Brignone told Live Science. What's more, previous research suggests that trends in deaths of despair vary by race and ethnicity but such data wasn't available in this study, she said. Also, the researchers weren't able to directly link diseases of despair to deaths of despair for individuals. "Rather, we compare trends in morbidity and mortality in more general terms," she said.

It will also be important to understand the impact of COVID-19 on diseases of despair, Brignone said.

"COVID-19 highlights many of our existing vulnerabilities," Brignone said. The disease has exacerbated unemployment, isolation, uncertainty and barriers to care, which are all associated with an increased risk of diseases of despair, she said.

"Fortunately, we do have effective treatments for depression and addiction," she said. "We have to improve outreach to people in need and remove barriers to care," such as with the institution of telehealth. Policies and programs to prevent the loss of healthcare coverage and replace lost income will likely also help decrease the impact of COVID-19 on diseases of despair, she said.

Originally published on Live Science.

The U.S. Food and Drug Administration (FDA) has identified at least 77 hand sanitizers that contain dangerous levels of methanol, a toxic substance that can cause nausea, nerve damage and blindness when absorbed through the skin and death, if ingested.

In June, the FDA issued a warning about nine tainted hand sanitizers made by a company called Eskbiochem, Live Science previously reported, but since then, the agency has flagged dozens of additional products that contain dangerous levels of methanol, also known as wood alcohol, The Washington Post reported. The agency keeps a running list of these sanitizers on its website and notes that the products pose a particular risk to young children, who may accidentally ingest them, and for adults who purposefully drink the products as an alcohol substitute.

But how are so many products becoming tainted with methanol in the first place? Most likely, the surge stems from sloppy manufacturing processes, wherein producers may not properly remove methanol that naturally arises during alcohol distillation, or they may violate FDA guidelines by starting with an already distilled high-methanol solvent as their base, sources told Live Science. (Methanol distillates are a common ingredient in antifreeze and racing fuel.)

And unfortunately, while experts can smell the difference between methanol and ethanol, most consumers won't be able to detect this difference. And "methanol" will not be listed in the ingredients on the bottle. Instead, people should check the FDA's list of recalled sanitizer products to make sure theirs is not on it, and avoid unknown brands, experts told Live Science.

Related: Hand sanitizer sold out? Here's how to make your own.

Methanol can be lethal at fairly low doses: Ingestion of as little as 2 tablespoons (30 milliliters) of methanol can be deadly for a child, and 2 to 8 ounces (60 to 240 milliliters) can be deadly for an adult, Live Science previously reported. Even if only applied to the skin, methanol can be absorbed and cause severe illness and nerve damage, Dr. William Banner, Medical Director of the Oklahoma Center for Poison and Drug Information and a past president of the American Association of Poison Control Centers, told Live Science.

Topical methanol can be particularly dangerous for children, who have a greater ratio of skin surface area to body weight as compared with adults, Banner added. That said, consumers would likely need to apply the product repeatedly (as one does with hand sanitizer) to absorb a dose high enough to become poisoned, he said.

Lessons from distilleries 

Methanol contamination is a problem that distillers appreciate all too well — it's why illicit moonshine and other homemade liquors may be riskier to consume than spirits made by legitimate distilleries.

Alcohol production begins with the fermentation of sugars to produce both methanol and ethanol, the kind of alcohol that's considered fairly safe to drink and one of the best base ingredients for hand sanitizer, Live Science previously reported. Following fermentation, manufacturers boil the alcohols and collect their vapors, allowing them to condense into a concentrated "distillate." But methanol boils at a lower temperature than ethanol and therefore evaporates first in this distillation process. 

When ethanol does begin to boil, at 173.1 degrees Fahrenheit (78.37 degrees Celsius), manufacturers must "cut" the stream of alcohol and swap out their collection container; this ensures that the final product contains primarily ethanol, and the excess methanol gets tossed, Mike Blaum, co-owner and chief distiller of the Blaum Bros. Distilling Co. in Galena, Illinois, told Live Science. After the methanol is removed, the remaining distillate is mostly ethanol, the key ingredient in liquor, along with other compounds that provide flavor. 

A very small amount of methanol does end up in the final beverage, but the dose must be kept below a certain threshold so as not to pose significant health risks, according to a 2001 report in the journal Human and Experimental Toxicology. For example, the FDA caps the maximum permitted level of methyl alcohol in brandy at 0.35%.

While commercial alcohol producers undergo rigorous safety checks to prove they've done this correctly, unregulated moonshine makers do not.

"For us, we really know how to ensure that there's no risk of methanol or any other toxicity," Blaum said. As a well-trained distiller, "you can smell and you can taste the difference" when the ratio of methanol to ethanol becomes too high, he said.  In addition to these sensory cues, distillers monitor the density of the distillate and the temperature of various components within the apparatus that the alcohols flow through. Companies also periodically send distillate samples to labs equipped with gas chromatography–mass spectrometry (GCMS) — a technique used to analyze the ratio of chemicals present within a particular batch, Blaum said.

Related: 7 ways alcohol affects your health 

Manufacturers also make sure their fermentation vats don't become overrun with bacteria that produce extra methanol, Live Science previously reported.

The same quality controls should be applied when producing alcohol for hand sanitizer, as Blaum Bros. and other American distilleries began to do in late March with guidance from the FDA and the Alcohol and Tobacco Tax and Trade Bureau. The distilleries have been directed to follow formulas for hand sanitizer provided by the World Health Organization (WHO) and the FDA. These recipes call for a mixture of 96% ethanol alcohol by volume (ABV), hydrogen peroxide diluted to 3% of its maximum concentration, and glycerol diluted to 98%. (Recipes for sanitizer with other alcohols as the base, such as isopropyl alcohol, use slightly different ratios.)

"If you're doing your due diligence, it's hard to do it incorrectly," Blaum said. 

Although the distillery initially brewed its own ethanol for sanitizer, Blaum Bros. now purchases distilled ethanol in bulk at the start of production. As hand sanitizer sales skyrocketed at the start of the pandemic, Blaum said that pure ethanol distillates were in short supply. Manufacturers who made the contaminated sanitizers flagged by the FDA may have used a high-methanol distillate from the start, given that ethanol became difficult to procure, he noted. But that's only speculation, he said.  

Buying the right sanitizer 

In its warning about tainted hand sanitizers, the FDA noted that the products were mislabeled as containing ethanol but then "tested positive for methanol contamination." Unfortunately, there may not be a sure-fire way for consumers to check their sanitizers for contamination if they do purchase mislabeled goods, Banner said. 

"I wouldn't expect the general public to know what methanol smells like," Blaum noted. While other toxins removed during distillation have distinct scents — ethyl acetate smells like nail polish remover, for example — methanol smells similar to ethanol but with a slightly more synthetic or "chemical" odor, he said. People outside the distilling business may not be able to sniff out the difference, and what's more, sketchy sanitizer manufacturers "may very well be putting a scent in the hand sanitizer" to mask any telltale odors, Blaum added. 

"I'd just follow the FDA warnings" to keep up with which sanitizers are safe, and call the poison control center with any questions about unfamiliar products, Banner said. "Be aware that sometimes 'cheap' might not always be so good," he said, adding that obscure products made by small companies "who just jumped into a market" might not be as trustworthy as established brands. In any case, it's best practice to check the FDA list before using a new product. 

Related: Here's how long the coronavirus will last on surfaces, and how to disinfect those surfaces.

In addition, the FDA warns consumers to be wary of products marketed with misleading claims, such as the ability to "provide prolonged protection" against COVID-19. No hand sanitizers are approved by the FDA before entering the market, so products labeled "FDA-approved" should also raise alarm. Products packaged to look like drinks, candy or liquor bottles, as well as those marketed as drinks or cocktails, may place children at particular risk because their outward appearance may tempt kids to drink them. 

Signs of methanol exposure 

As more sketchy sanitizers may crop up as the pandemic continues, here's what you should know about methanol exposure and its effects on the body:

"Methanol is no more toxic than ethanol," at least when first ingested, Banner noted. The trouble arises in the liver, where an enzyme called alcohol dehydrogenase metabolizes both alcohols, he said. Unlike ethanol, methanol converts into formaldehyde as it breaks down, among other metabolites; the formaldehyde then gets passed to a second enzyme that transforms the compound into formic acid. The accumulation of formic acid drives down the pH of the blood, making it dangerously acidic; that disrupts the metabolic processes required for cells to produce energy; and it leads to a buildup of waste products, such as lactate, according to a 2011 report in The Indian Journal of Ophthalmology.

This harmful combination of acidity and metabolic disruption hits nerve cells hardest, and specifically cells of the retina and optic nerves, which begin to "swell" and can be permanently damaged as a result of formic acid exposure, Banner said. But because the body takes time to metabolize methanol, it can take about four to six hours for symptoms to emerge, he said.

People who experience vision loss after methanol exposure describe their vision first going blurry and then everything looking as if they were "walking through a snowstorm," Banner said. If these individuals don't quickly receive kidney dialysis, "they will be permanently blind," he said. In addition to dialysis, people with methanol poisoning may be treated with a drug called fomepizole, which inhibits alcohol dehydrogenase and thus stops the liver's production of formic acid. More rarely, patients may be treated with doses of ethanol, because both alcohols compete for alcohol dehydrogenase and the presence of one slows the metabolism of the other.

Besides vision loss, people exposed to methanol may experience nausea, vomiting, headache, seizures or coma, according to the FDA. The earliest signs of exposure often include feeling a bit intoxicated and beginning to hyperventilate as the body reacts to increased acid in the blood, Banner added.

Originally published on Live Science. 

A man's medication for alcohol dependence caused him to have a strange reaction to hand sanitizer, according to a new report of the case.

The 43-year-old man was visiting his bank when he began experiencing what looked like an allergic reaction — he suddenly became flushed, nauseated and uneasy. His symptoms started after he had applied hand sanitizer to his hands when he arrived at the bank, to follow the rules that were in place for the COVID-19 pandemic, according to the report, published in the July issue of the journal Alcohol and Alcoholism.

The man was rushed to the emergency room, where he was found to have a fast heartbeat, or tachycardia, along with redness on his chest and face.

For three years, the man had been taking disulfiram, a medication to treat alcohol abuse that causes hangover-like effects — including flushing, headache, nausea, vomiting and fast heart rate — almost immediately after consuming alcohol. The drug causes these unpleasant side effects, which typically last about an hour,  to deter people from drinking; and the man said he had abstained from alcohol for three years. 

Disulfiram works by blocking the enzyme aldehyde dehydrogenase, which helps rid the body of acetaldehyde, a breakdown product of alcohol that plays a role in causing the symptoms of a hangover. Thus, taking disulfiram leads to a buildup of acetaldehyde if people are exposed to alcohol. The drug has been approved for more than 50 years to treat alcohol dependence, and about 200,000 people in the U.S. regularly take the drug, according to Medscape.

Because exposure to even small amounts of alcohol can trigger a reaction, people taking disulfiram are warned not to use alcohol-containing products, such as some sauces, vinegars, cough syrups and mouth washes; and to avoid breathing in fumes that may contain alcohol, such as from paint thinner or varnish, according to the Mayo Clinic. Hand sanitizers typically contain 60% to 70% alcohol, and should also be avoided, according to the National Alliance on Mental Illness.

In the man's case, doctors suspected a reaction to alcohol due to disulfiram, and he was treated with an antihistamine along with an injectable form of vitamin C, which are some of the recommended supportive treatments for a disulfiram-alcohol reaction, according to the U.S. Substance Abuse and Mental Health Services Administration.

The man's symptoms resolved after an hour, and he was released from the hospital but warned to either not use sanitizer or to stop using disulfiram, the report said. Sole author of the report, Dr. Avinash De Sousa, of Lokmanya Tilak Municipal Medical College in Mumbai, India, is the patient's psychiatrist, and after a consultation, "it was decided that because sanitizer use would be rampant, [the man] would cease disulfiram for the time being," De Sousa wrote.

A recent study, also published the July issue of Alcohol and Alcoholism, suggested that inhalation of the alcohol fumes from hand sanitizer, rather than absorption of alcohol through the skin, appears to be the main way that the alcohol in hand sanitizers reaches the bloodstream.

Originally published on Live Science.  

The Food and Drug Administration (FDA) is warning the public not to use hand sanitizer products made by a Mexican company because they contain a poisonous substance called methanol, which can be deadly when absorbed through the skin or ingested.

The warning applies to nine hand sanitizer products made by the company, called Eskbiochem, according to a statement from the FDA. The agency said it found methanol in samples taken from several of the company's products. 

Exposure to methanol can cause nausea, vomiting, headache, blurred vision, permanent blindness, seizures, coma, permanent damage to the nervous system or even death, according to the FDA.

People may be at risk for methanol poisoning if they use the substance on their hands, but the greatest risk for poisoning occurs when people ingest methanol, either accidentally (for example, if the product is ingested by a child) or intentionally (which may be the case for teens or adults who drink the products as an alcohol substitute), the FDA said.

The nine products are known as All-Clean Hand Sanitizer, Esk Biochem Hand Sanitizer, CleanCare NoGerm Advanced Hand Sanitizer, Lavar 70 Gel Hand Sanitizer, The Good Gel Antibacterial Gel Hand Sanitizer, Saniderm Advanced Hand Sanitizer and three varieties of CleanCare NoGerm Advanced Hand Sanitizer, the statement said.

Consumers who have these products should stop using them and dispose of them immediately. People who have been exposed to these products should seek immediate medical treatment to reverse the toxic effects of methanol poisoning, the agency said.

The agency has asked Eskbiochem to remove the products from the market, but the company has yet to take action, the statement said. 

So far, the FDA has not received reports of illness tied to these products. 

To be marketed as a hand sanitizer, a product should contain ethyl alcohol (also called ethanol), isopropyl alcohol (isopropanol) or benzalkonium chloride as the active ingredient, Live Science previously reported. 

Although methanol is a type of alcohol, it is extremely poisonous and is found in products such as antifreeze and racing fuel, according to the National Institutes of Health (NIH). The body metabolizes methanol into a compound called formic acid, which is highly toxic to cells, Live Science previously reported. Ingestion of as little as 2 tablespoons (30 milliliters) of methanol can be deadly for a child, and 2 to 8 ounces (60 to 240 milliliters) can be deadly for an adult, the NIH says.

In the past, some people have been poisoned with methanol after trying to make their own alcohol, or from drinking spirits that were manufactured illegally.  

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Originally published on Live Science. 

UPDATED on May 8 -- Editor’s note: Live Science has found that the elephants discussed in this article were not drunk; they were just resting. Read more about where the story came from and how it went viral.

Tweets mentioned in the article that describe the "drunk" elephants have since been deleted and are no longer available.

Large public gatherings are currently prohibited in many places to prevent the spread of the new coronavirus, but that didn’t stop a group of Asian elephants from partying in a field in Yunnan Province in China, where they found and drained vats of corn wine. 

Two elephants drank so much wine that they passed out in a tea garden.

A photo of the inebriated elephants — lying curled up back to back on a dirt bed amid the greenery — went viral after it was shared on Twitter on March 18 by Parveen Kaswan, a conservationist and an Indian Forest Service officer. Kaswan mentioned in the tweet that wild elephants have a taste for booze, quipping that these particular pachyderms had turned to alcohol "to sanitize [their] trunks," and were sleeping off the aftermath.

Related: Incredible photos capture last glimpse of long-tusked 'elephant queen'

Asian elephants (Elephas maximus indicus) inhabit grasslands and forest habitats across countries in southern Asia, and there are estimated to be fewer than 50,000 of them in the wild, the World Wildlife Fund says. 

But in China there are only 250 of these elephants left, and they face the looming threat of local extinction, Kaswan tweeted.

In another tweet, Kaswan posted a photo of the elephant herd "when they were all sober," clustered together amid rows of crops. In forest regions where the elephants live, locals are aware of the animals' interest in human-made alcohol, Kaswan said. But even when people bury their liquor, "somehow elephants find it," Kaswan wrote in the tweet.

Elephants will even "mark" locations where they have previously found alcohol and come back later to see if there's more, Kaswan added.

Persistent rumors and anecdotes had long suggested that African elephants regularly become drunk on fermented marula fruit, though scientists determined more than a decade ago that this was likely a myth. An animal the size of an elephant — weighing more than 6,600 lbs. (3,000 kilograms) — would have to consume 400 times the amount of fruit in its normal diet and not drink any water for the alcohol to make it intoxicated, researchers reported in 2006 in the journal Physiological and Biochemical Zoology.

However, elephants that come across caches of liquor or wine might guzzle the beverage for its sweet taste, which could lead to drunkenness, Shermin de Silva, a cofounder of Sri Lanka's Elephant Forest and Environmental Trust, previously told Live Science.

Other types of wild creatures have demonstrated the effects of consuming too much alcohol. In 2011, a moose in Sweden got drunk after eating fermented apples and wound up entangled in a tree, according to the Smithsonian. White-tailed deer often browse on fermented apples in orchards, making them "stumble-y" and "sleepy," Don Moore, associate director of the Smithsonian National Zoo in Washington, D.C., told National Geographic. 

And chimpanzees, our closest living primate relatives, appear to enjoy the taste of alcohol, soaking up fermenting palm sap with leaves and then squeezing the booze into their mouths, Live Science previously reported.

But there's one animal that imbibes more than any other — the Malaysian pen-tailed shrew. The shrews' diet consists entirely of fermented nectar that is about 3.8% alcohol, suggesting that the shrews would be perpetually drunk. However, despite the nectar's high alcohol content, the shrews have evolved to metabolize it so efficiently that they don't become inebriated at all, scientists discovered in 2008.

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Originally published on Live Science.

Hand sanitizers provide a convenient and effective way to clean your hands if soap and water aren't available and your hands aren't covered in visible dirt or grease. According to a 2019 ruling by the FDA, a product can be marketed as a hand sanitizer if it contains ethyl alcohol (also called ethanol), isopropyl alcohol (isopropanol) or benzalkonium chloride as the active ingredient. 

The FDA hasn't made a decision on whether to categorize those three ingredients as "generally recognized as safe" because the agency doesn't think there is enough research to say. But they're also not pulling the products from shelves. Ingredients other than those three have shown little to no evidence of being effective at killing germs and have not won the FDA's approval. 

How does hand sanitizer work? 

The key ingredient in most hand sanitizers is alcohol. Chemically speaking, alcohols are organic molecules made of carbon, oxygen and hydrogen. Ethanol is the chemical in alcoholic drinks and is the chemical most people are thinking of when they say alcohol. Propanol and isopropanol (isopropyl alcohol) are two other alcohols that are common in disinfectants because they're highly soluble in water, just like ethanol.

Alcohols destroy disease-causing agents, or pathogens, by breaking apart proteins, splitting cells into pieces or messing with a cell's metabolism, according to a 2014 review published in the journal Clinical Microbiology Reviews. Solutions with as little as 30% alcohol have some pathogen-killing ability, and the effectiveness increases with increasing alcohol concentration. Studies have shown that alcohol kills a more broad variety of bacteria and viruses when the concentration exceeds 60%, and it works faster as the concentration increases. But the effectiveness of alcohol seems to top out at about a 90-95% concentration. 

Another strength of alcohol is that the bacteria it kills don't develop a resistance to it, so alcohol doesn't lose effectiveness with continued use. 

According to the 2014 review, ethanol is so powerful that a few studies have found that in high concentrations, it's better at getting rid of three species of disease-causing bacteria — Escherichia coli, Serratia marcescens and Staphylococcus saprophyticus — compared with washing hands with regular or antibacterial soap. 

Related: Hand sanitizer sold out? Here's how to make your own.

But alcohol doesn't work for all germs, such as norovirus; Clostridium difficile, which can cause life-threatening diarrhea; or Cryptosporidium, a parasite that causes a diarrheal disease called cryptosporidiosis, the Centers for Disease Control and Prevention says. Hand sanitizers also don't remove harmful chemicals like pesticides or heavy metals, nor does hand sanitizer work well on especially dirty or greasy hands. So, soap and water still win the contest overall. 

There are a few small-scale studies demonstrating that an alcohol-free hand sanitizer containing benzalkonium chloride as the active ingredient, at a concentration of 0.13%, is just as effective and even more effective than alcohol at getting rid of bacteria. The alcohol-free hand sanitizer that was tested was called HandClens, and the scientists who conducted the research on it worked for the now-closed laboratory that developed the product. That doesn't mean benzalkonium chloride isn't effective, but there doesn't seem to be independent research to suggest that it's better than alcohol. Plus, benzalkonium chloride might be harmful for some individuals, especially at higher concentrations, according to the Hazardous Substances Database. 

According to the CDC, hand sanitizer without alcohol may not kill as many germs and may only reduce the growth of germs rather than killing them outright. The CDC recommends hand sanitizers with at least 60% alcohol in them for maximum effectiveness. 

Does hand sanitizer expire? 

Hand sanitizer doesn't really expire. There will likely be an expiration date on the bottle because hand sanitizers are regulated by the FDA, which requires certain things to be on the packaging, including an expiration date. The expiration date is supposed to be the last date at which the product contains the ingredients in the amount specified on the label. Whether the manufacturer has tested how long the product meets the label claim or they just came up with an arbitrary date to determine the expiration date is mostly unknown to consumers. (Manufacturers are supposed to conduct testing, but not all do.)  

Alcohol is a shelf-stable chemical according to its safety data sheet from chemical-supplier Sigma Aldrich. This means that if alcohol is kept in a sealed container at room temperature it will remain at the same concentration for a very, very long time. 

However, alcohol evaporates easily because of its relatively low boiling point, and over time, as the bottle is opened and closed, some alcohol may escape and the concentration of alcohol in your hand sanitizer might start to decrease. Still, if you keep the bottle closed and at room temperature, you're likely to have an effective product for as long you need it. 

Is hand sanitizer bad for you or toxic? 

Alcohols are considered safe for use as an antiseptic and generally have no toxic effect on the skin, although repeated use may cause dryness or mild irritation, according to the Hazardous Substances Database. Several studies have shown that repeated use of hand sanitizer is less irritating than repeated hand washing with soap. But damaged skin is more susceptible to irritation from alcohol. 

And let's be honest, would you rather have some mild skin irritation, or distribute and contract an illness? 

Additional resources: 

• Read more about why hand sanitizer is a good alternative to soap and water, according to the FDA. 
• Here's more info on what the FDA considers hand sanitizers to be. 
• And here are the guidelines from the CDC on hand washing and hand sanitizer use. 

When a woman in Pennsylvania needed a life-saving liver transplant, she repeatedly ran up against one vexing problem: She kept testing positive for alcohol — which disqualified her from a transplant — even though she swore she hadn't been drinking. 

Doctors would later discover that something quite strange was going on: Microbes in the woman's bladder were fermenting alcohol, according to a new report of the case.

The woman's condition is similar to a rare disorder called "auto-brewery syndrome" (ABS), in which microbes in the gastrointestinal tract convert carbohydrates into alcohol. People with ABS can get drunk just from eating carbs, Live Science previously reported. But in the woman's case, the fermentation was taking place in her bladder, which makes her condition distinct from ABS, the report said. In her case, the alcohol didn't get from the bladder into the bloodstream, so the woman didn't appear intoxicated.

The woman's condition was so rare that it didn't even have a name yet. Her doctors proposed calling it "urinary auto-brewery syndrome" or "bladder fermentation syndrome."

Related: 9 weird ways you can test positive for drugs

The 61-year-old woman went to the University of Pittsburgh Medical Center (UPMC) Presbyterian Hospital because she had cirrhosis, or scarring of the liver, and needed to be placed on the liver-transplant waitlist, according to the report. She also had diabetes that was not under control, meaning her blood sugar levels were high.

Previously, the woman had visited another hospital, but she could not get on the liver-transplant waitlist there, because her urine repeatedly tested positive for alcohol. Doctors at that hospital told her she needed treatment for alcohol addiction.

At UPMC Presbyterian Hospital, the woman also tested positive for alcohol (ethanol) on a urine drug test, leading doctors to suspect she was "hiding an alcohol use disorder," the authors wrote in the report, published Monday (Feb. 24) in the journal Annals of Internal Medicine. But she consistently denied drinking alcohol.

That's when doctors noticed something curious: Urine tests for two metabolites of alcohol, ethyl glucuronide and ethyl sulfate, were negative for the woman. This was puzzling because at least one of these metabolites should be present in urine for several days after a person drinks alcohol, said study senior author Dr. Kenichi Tamama, an associate professor of pathology and medical director of UPMC's Clinical Toxicology Laboratory. "This was the first clue" that something was off, Tamama said. 

The woman's blood tests for ethanol were also negative, and she did not appear intoxicated.

Tamama additionally noticed that the woman had very high levels of glucose (sugar) in her urine, due to her poorly controlled diabetes, as well as high levels of yeast. The doctor wondered if the microbes colonizing the woman's bladder were fermenting that sugar into alcohol.

"As I went over the medical record of the patient and learned the situation of the patient, I started feeling obliged to do something for this patient, because she might have been falsely mislabeled as an alcohol abuser," Tamama told Live Science.

To test Tamama's idea, the researchers conducted a careful experiment; they took a sample of the patient's "freshly voided urine" and quickly put it on ice. Then, they incubated the sample in a test tube at body temperature (98.6 degrees Fahrenheit, 37 degrees Celsius) and saw "remarkably high levels of ethanol production," the report said. This production did not occur when the sample was incubated at a lower temperature (39 F, 4 C) or if the researchers added a chemical to block fermentation.

"We concluded that the discrepant test results were best explained by yeast fermenting sugar in the bladder," the authors wrote. They also identified the yeast Candida glabrata in the woman's urine. This microbe is part of the normal microbiome in people, and it is closely related to brewer's yeast, the authors said.

As a result of these findings, the woman was reconsidered for liver transplantation, the report said.

There have been a few previous reports of people with diabetes who were found to have ethanol in their urine as a result of yeast fermenting sugar into alcohol. However, these earlier reports were limited in various ways; for example, in one previous case, the fermentation was found postmortem. In other cases, the fermentation was suspected to have occured in a test tube only (as a result of the sample being left out of the fridge), not in the bladder.

The new report alerts doctors to "the importance of recognizing urinary auto-brewery syndrome when it is present," the authors said.

At the time of publication, the authors did not have consent from the patient to provide an update on how she's doing now, Tamama said.

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Originally published on Live Science. 

For six long years, a man would experience mysterious bouts of drunkenness without ever drinking a drop of alcohol. 

Eventually, he was diagnosed with a rare condition that filled his gut with booze. 

The 46-year-old man had auto-brewery syndrome (ABS), a condition that causes bacteria in the gut to transform carbohydrates into intoxicating alcohol, according to a report of the man's case, published Aug. 5 in the journal BMJ Open Gastroenterology. The condition flares up when people consume sugary or carb-heavy foods and beverages, and throws them into a drunken haze just as if they'd knocked back too many beers, the man's doctors wrote.

The man was "unable to function, and it was mainly after meals," Dr. Fahad Malik, co-author of the report, told the Today show. The man's symptoms emerged after he received antibiotics in 2011 following a "complicated traumatic thumb injury," the report said. The medication likely disrupted his gut microbiome, or the community of  microorganisms, such as bacteria and fungi, living there. "No one believed him" when the man said he didn't drink, Malik said. 

Related: 7 Ways Alcohol Affects Your Health

The patient experienced a "brain fog," displayed uncharacteristically aggressive behavior and was even arrested for drunk driving. On that occasion, the man's blood alcohol concentration registered at twice the legal limit, but he insisted he hadn't been drinking. The hospital personnel and police didn't buy it, the report noted.

Following his arrest, the man's aunt came across a case report describing a patient in Ohio who was treated for a similar condition. She and the man traveled to the Ohio clinic, where doctors searched the man's poop for boozy microbes. They uncovered strains of Saccharomyces boulardii and Saccharomyces cerevisiae, otherwise known as brewer's yeast, in the stool samples. At this point, they suspected the man had auto-brewery syndrome but asked him to chow down on some carbs, to make sure. 

Eight hours later, the man's blood-alcohol concentration spiked to more than 0.05% (close to the legal blood alcohol limit for driving), confirming his unusual diagnosis. 

Despite receiving anti-fungal treatment and being placed on a no-carb diet, the man still experienced flare-ups. He saw internists, psychiatrists, neurologists and gastroenterologists in attempts to get his spontaneous drunkenness under control. During this time, one extreme episode left the man with a dangerous head injury and a potentially fatal blood alcohol concentration of 0.4%. "Here too, the medical staff refused to believe that he did not drink alcohol despite his persistent denials," the report said.

Then, the man sought help at Richmond University Medical Center in Staten Island, New York, where doctors placed him on antibiotics and monitored him closely for about two months. The therapy successfully rid the patient's gut of the boozy microbes, though, at one point, the man "ate pizza and drank soda while on this treatment, resulting in a severe [auto-brewery syndrome] relapse," the report said. The patient was then prescribed probiotics to promote the growth of helpful gut bacteria. Slowly, the man was able to incorporate carbs back into his diet. 

A year and a half later, the man can enjoy a slice of pizza without fear of intoxication — or potential alcohol-induced liver damage. 

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Originally published on Live Science. 

It's common knowledge that drinking too much alcohol can lay waste to your liver. But now, researchers have spotted a strain of gut bacteria that produces its own booze in copious amounts — high enough to potentially pose a risk of liver problems in people who don't drink at all. 

Although much more research is needed to confirm the results, they suggest that these boozy bacteria may contribute to nonalcoholic fatty liver disease (NAFLD), a condition in which fat builds up in the liver for reasons unrelated to alcohol consumption.

The researchers first stumbled upon this unusual microbe while they were studying a patient with a curious condition: The patient had so-called auto-brewery syndrome (ABS), an extremely rare condition that leaves people drunk after eating sugary food. In the week before he sought medical care, the unfortunate patient became inebriated each time he consumed a carbohydrate-rich meal and his blood-alcohol concentration had occasionally spiked to potentially lethal levels, around 0.4%. He was even suspected to be a "closet drinker" by his friends, according to the new study, published today (Sept. 19) in the journal Cell Metabolism. 

ABS has been linked to yeast infections, wherein the fungus ferments alcohol in the intestines just as it brews beer in barrels; but in this case, yeast wasn't the culprit. 

The researchers looked to their patient's poop for answers. They found, not yeast, but strains of alcohol-producing bacteria called Klebsiella pneumonia. This is the first time that a bacterium has  been linked to ABS, study co-author Jing Yuan, a professor and director of the bacteriology laboratory at the Capital Institute of Pediatrics in Beijing, told Live Science in an email. Though the common gut bacteria poses no problem in healthy people, the microbe appeared to be producing four to six times the normal level of alcohol in the patient. 

Besides becoming intoxicated, the patient also suffered from severe liver inflammation and scarring due to a buildup of fat in the organ, his doctors noted. The condition, called nonalcoholic steatohepatitis, is a progressive form of NAFLD, and the researchers wondered if others with the disorder might carry the same "super-strain" of boozy bacteria.

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The team sampled the gut bacteria found in more than 40 people with NAFLD. Compared with about 50 healthy controls, the NAFLD patients hosted slightly more K. pneumonia in their guts than average. However, the alcohol-producing ability of those bacteria appeared unusually strong.  About 60% of sampled NAFLD patients had high- and medium-alcohol-producing bacteria in their gut, while only 6% of the controls carried these strains.   

To test if the boozy bacteria could cause fatty liver disease, the researchers isolated high-alcohol producing strains and fed them to "germ-free" lab mice, which don't have their own gut bacteria. Another group of mice received ethanol, while a control group ate only normal food for three months. Mice that ate the boozy bacteria began accumulating fat in their livers after one month and developed scarring after two months, similar to the mice fed ethanol. The extent of the liver damage correlated with the amount of alcohol produced — the more alcohol, the more damage. But the condition could be reversed with the administration of antibiotics.

The results suggest that K. pneumonia can indeed drive the progression of fatty liver disease, at least in mice. 

"That's something unique — that just changing one bacteria does it," said Rohit Loomba, director of the NAFLD Research Center at the University of California, San Diego. Loomba noted that K. pneumonia may be one of several bacteria that could inflict liver damage in animal models. Studies to confirm the findings in humans will be key to learning how and whether K. pneumonia mingles with other gut microbes to drive liver disease progression, he said.    

This isn't the first study to tie gut bacteria to liver disease. In a study published this year, Loomba and his colleagues found that people with NAFLD host distinct bacterial communities in their guts, depending on how far their disease has progressed. By analyzing these microbial signatures, the scientists were able to diagnose those with the most advanced stage of NAFLD, called cirrhosis, with 92% accuracy. In a similar 2017 study, the team learned they could predict the extent of scarring, or fibrosis, present in a patient's liver based on the composition of their gut microbiome.  

If microbes like K. pneumonia do indeed play a role in NAFLD in people, they might someday serve as targets for the treatment of the disease, Loomba added. 

In follow-ups with their human participants, the study authors found that levels of the high-alcohol producing strains dipped or disappeared in many of those who had undergone standard treatment for the disease and lost weight. The result suggests that there's a strong association between K. pneumonia and NAFLD progression, but whether the bacteria truly help cause the disease remains unclear. 

Yuan and his colleagues are now recruiting study participants for a larger, long-term study in adults and another study in children to learn "why some people have high-alcohol producing strains of K. pneumonia in their gut while others don’t" and whether the bacteria actually contribute to disease.    

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Originally published on Live Science. 

Drinking alcohol is known to raise women's risk of developing breast cancer, but many women aren't aware of this link, a new study from the United Kingdom suggests.

The study researchers analyzed information from 205 women who were undergoing breast cancer screening or seeking treatment for breast cancer symptoms at a U.K. hospital. The women were surveyed about their knowledge of risk factors for breast cancer.

About half the women surveyed knew that smoking was a risk factor for breast cancer, and 30% recognized obesity as a risk factor. But only about 20% knew that consuming alcohol was a risk factor, the study found.

Even among health care staff, knowledge of the connection between alcohol and breast cancer was still lacking — of 33 health care staff surveyed, 49% identified alcohol as a risk factor for breast cancer. [7 Odd Things That Raise Your Risk of Cancer (and 1 That Doesn't)]

The new study was conducted at a single health center in the U.K., and so the findings don't necessarily apply to the general population. But the findings do agree with previous research conducted in the United States: A 2017 survey by the American Society of Clinical Oncology found that 70% of Americans didn't know that drinking alcohol is a risk factor for cancer.

It's estimated that alcohol consumption is responsible for around 5% to 11% of all breast cancer cases, with higher risks seen among heavy drinkers. A recent study also estimated that drinking a bottle of wine a week is the equivalent of smoking 10 cigarettes per week for women, in terms of their overall cancer risk.

The new study also suggests that it may be difficult for people to estimate exactly how much alcohol they consume. The study showed that more than half of participants couldn't correctly estimate the alcohol content in any of four commonly consumed alcoholic drinks — a glass of wine, a pint of beer, a liter of cider and a bottle of liquor.

"This suggests that many women may be unaware that their level of alcohol consumption may be increasing their risk of breast cancer," the authors wrote in the June 18 issue of the journal BMJ Open.

It's possible that breast cancer screenings and visits for breast cancer symptoms might serve as "teachable moments" to inform women about ways to decrease their breast cancer risk, such as by reducing alcohol consumption, the authors said.

Indeed, when women in the study were asked how they would feel about having a 5-minute session in which they were provided with cancer prevention information at their breast cancer screenings or appointments for breast symptoms, about 30% percent said this would make them more likely to attend those appointments, and 70% said it would make no difference.

This suggests that "women would not be put off attending breast [cancer] screening or clinic appointments if they were aware they would receive some cancer prevention education," and may in fact be more likely to attend, the authors said.

However, more research would be needed about how to best deliver such information. Both patients and health care providers expressed concern that such sessions might come across as placing stigma on women who drink or blaming women for drinking.

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Originally published on Live Science.

A glass of clear moonshine may look identical to water, but this illicit alcoholic beverage is infamous for its potency — and for the peril associated with drinking it.

What is moonshine? Broadly, moonshine is any type of distilled liquor that's manufactured without government oversight, though some argue that moonshine can be labeled as such only when it is made with certain ingredients or comes from specific geographic regions, experts told Live Science.

People all over the world make and drink moonshine, particularly in places where alcohol is illegal or where legal alcohol is prohibitively expensive or hard to get. But producing spirits can be a tricky chemical process; manufacturers' mistakes, ignorance or shortcuts can yield a highly toxic product. 

So, how does that happen, and how can you tell if a glass of moonshine is safe? [7 Ways Alcohol Affects Your Health]

Alcohol in moonshine and other intoxicating drinks comes from fruits or grains that are fermented — that is, they are exposed to yeasts or bacteria that convert sugar molecules to carbon dioxide and alcohol.

Ingredients for moonshine vary widely depending on what's available. In the early 20th century, American moonshiners typically made their brews from corn mash; in fact, legal versions of traditional American moonshine are commercially produced today by craft distilleries in the United States.

But moonshine is also made from grapes, plums or apricots (Armenia), barley (Egypt), palm tree sap (Myanmar), bananas (Uganda) and cashew fruit (India), said Kevin Kosar, author of "Moonshine: A Global History" (Reaktion Books, 2017).

"It's just basic chemistry. If you can tease sugar out of something, you're on your way to making a drink," Kosar told Live Science.

Potent potables

Fermentation produces two forms of alcohol: ethanol and methanol, which is also known as wood alcohol. Methanol is released from pectin, and is therefore more abundant in fermented fruit, according to research published by the American Chemical Society. Though ethanol is generally considered safe for drinking, both ethanol and methanol suppress the central nervous system and inhibit brain function. Consuming too much alcohol — even the "safe" kind — can cause alcohol poisoning, affecting heart rate and breathing and even leading to coma and death, according to the Mayo Clinic.

Methanol is far more dangerous than ethanol, said Anne Andrews, a professor of psychiatry, chemistry and biochemistry at the University of California, Los Angeles. In the human body, methanol is converted to formaldehyde — the same substance in embalming fluid — and then to formic acid, which is highly toxic to cells, Andrews told Live Science.

"It interferes with their mitochondria, and actually causes cells to suffocate," Andrews said.

After fermentation, moonshine is distilled to concentrate the ethanol and other volatile flavor ingredients. However, ethanol boils at 173.1 degrees Fahrenheit (78.37 degrees Celsius), while methanol boils at 148.5 degrees F (64.7 degrees C). Because methanol has a lower boiling point and it evaporates earlier, it can become concentrated in the distillate — the vapor that is condensed and collected during distillation, Andrews said.  

Regulated alcohol production — including commercial moonshine — is carefully monitored. Products are rigorously tested to ensure that methanol is separated from the beverage and that the amount of alcohol by volume is clearly identified on packaging and labels. But for unregulated moonshine makers, there are no universal guidelines or enforced safety checks. Moonshine can therefore be more potent than legal beverages, and a batch of moonshine can quickly turn toxic, Andrews said.

If fermentation vats are unsterilized, that can promote the growth of bacteria that pump out methanol, resulting in a higher methanol concentration than expected, Andrews explained. And if moonshiners aren't cultivating microbial communities for fermenting the moonshine — "inoculating" it with species that produce mostly ethanol — unexpected shifts in environmental microbes can also generate a methanol spike.

"That moonshine could have been safe for years," Andrews said. "But then something changes in the environment, affecting local microbes that are doing the fermentation. Now there's a higher concentration of methanol, and the person making it would never know."

Poison for profit

In some cases, greed is the cause of moonshine's toxicity. Unscrupulous manufacturers that want to increase the volume of their moonshine either don't remove methanol or add a cheap, toxic alcohol like isopropyl, which is found in rubbing alcohol, said Kosar. Though this tactic may boost profits, it significantly raises the risk that the drink will be poisonous.

"With alarming regularity, there are stories — often coming from parts of Asia — where people go out and buy illicit alcohol, they have a party, and then hours into the party, people just start dropping and having convulsions," Kosar said.

Drinking alcohol with high levels of methanol can also lead to blindness: Methanol caused 130 deaths and 22 cases of blindness in just six months during Prohibition, according to a 1922 article in The New York Times that cited a report by the U.S. National Committee for the Prevention of Blindness.

Even when moonshine doesn't contain toxic levels of methanol, it's difficult for a casual drinker to tell how strong a batch may be without testing it — an uncertainty that could lead to accidental alcohol poisoning. The best way for drinkers to stay safe is to give illicit alcohol a wide berth, Kosar said.

"Unless you're a close friend of the person producing the moonshine and have absolute trust in their competence to produce it, don't drink it," he warned.

Editor's Note: This story was updated to correct the boiling points of ethanol and methanol; to note the legal production of commercial moonshine; and to add that while chemical tests do exist to test for methanol in moonshine, most casual drinkers don't have these on hand while consuming these beverages.

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Originally published on Live Science.

Drinking a bottle of wine per week may be like smoking five to 10 cigarettes in the same time period, in terms of cancer risk, according to a new study from the United Kingdom.

The study, published today (March 28) in the journal BMC Public Health, is the first to estimate the "cigarette equivalent" of alcohol, with regard to cancer risk.

The researchers found that the increase in cancer risk tied to drinking one bottle of wine per week is equivalent to smoking five cigarettes per week for men and 10 cigarettes per week for women.

The goal of the research is to better convey the cancer risks that are tied to moderate alcohol consumption, which is generally thought to be less harmful than smoking cigarettes. Indeed, studies in both the U.S. and U.K. have found that many people aren't aware of alcohol's link to cancer. For example, a 2017 survey from the American Society of Clinical Oncology found that 70 percent of Americans didn't know that drinking alcohol is a risk factor for cancer.

"Our estimation of a cigarette equivalent for alcohol provides a useful measure for communicating possible cancer risks that exploits successful historical messaging on smoking," lead study author Dr. Theresa Hydes, of the Department of Gastroenterology and Hepatology at the University Hospital Southampton NHS Foundation Trust, said in a statement. "We hope that by using cigarettes as the comparator we could communicate this message more effectively to help individuals make more informed lifestyle choices." [7 Ways Alcohol Affects Your Health]

Dr. Richard Saitz, an addiction medicine specialist and chair of the Department of Community Health Sciences at Boston University School of Public Health, said that the study's comparison makes sense.

"I think it's about time that we communicate the cancer risks of alcohol — it's really been under the radar [and] this way is a good way to do it," said Saitz, who wasn't involved with the study.

Still, the researchers stress that the study isn't saying that moderate alcohol consumption is the same thing as smoking. The study only considered cancer risk, and not the risks of other health conditions, such as heart disease. In addition, the study looked at the lifetime risk of cancer in the general population, which might differ from an individual's cancer risk from either smoking or alcohol, the authors said.

Alcohol vs. cigarettes

To put alcohol's cancer risks in perspective, the study aimed to answer the question: In terms of cancer risk, how many cigarettes are in a bottle of wine? One bottle contains about 80 grams (2.5 ounces) of pure alcohol.

The researchers used national data from the U.K. on the lifetime risk of cancer in the general population as well as previously published research on the relationship between alcohol, smoking and cancer.

They estimated that, among nonsmokers, drinking one bottle of wine per week is tied to a 1.0 percent increase in lifetime cancer risk for men; and a 1.4 percent increase in lifetime cancer risk for women. In other words, if 1,000 men and 1,000 women each drank one bottle of wine per week, about 10 extra men and 14 extra women would develop cancer at some point in their lives, the researchers said. The higher risk among women is mainly due to the link between alcohol consumption and breast cancer.

This risk was comparable to smoking five cigarettes per week for men and 10 for women.

A "known carcinogen"

"Everybody knows that cigarettes cause cancer," Saitz told Live Science. "Hearing that some amount of alcohol is the equivalent of some amount of cigarettes" in terms of cancer risk, is helpful for the general public, he said.

Saitz noted that there's been little discussion of the cancer risks tied to alcohol, even though alcohol is a known carcinogen. Even dietary guidelines discuss the recommended number of alcoholic drinks per day.

"If I didn't call it alcohol or wine or beer or cocktails, and I just called it a carcinogen, no one would be talking about how many glasses of a carcinogen you could have," Saitz said.

The study authors noted that because the study only considered cancer risk, it didn't take into account other diseases tied to smoking or alcohol use, such as respiratory, cardiovascular or liver diseases.

The authors also pointed out that smokers typically consume far more than five to 10 cigarettes per week — the average smoker in the U.K. consumes around 80 cigarettes per week, and the average smoker in the U.S. consumes around 100 cigarettes per week.

Still, "these findings highlight moderate levels of drinking as an important public health issue," the authors concluded.

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Originally published on Live Science.

Alcohol consumption may be more harmful than thought, particularly for young and middle-age adults, a new study suggests.

Although drinking alcohol in moderation is often thought to be good for you, the authors point out that many studies on the benefits of alcohol consumption involve people ages 50 and older. This paints a skewed picture of the benefits of alcohol, because it eliminates people who have died from alcohol consumption at younger ages.

That's worrisome, because more than one-third of deaths from alcohol consumption occur among people ages 20 to 49, according to the study, published yesterday (Feb. 28) in the Journal of Studies on Alcohol and Drugs.

Indeed, "deceased persons cannot be enrolled in" medical studies, the study authors wrote. What's more, "those who are established drinkers at age 50 are 'survivors' of their alcohol consumption who [initially] might have been healthier or have had safer drinking patterns" compared with others, according to the study, led by Dr. Timothy Naimi, of Boston Medical Center's Clinical Addiction Research and Education Unit. [7 Ways Alcohol Affects Your Health]

The findings add to a growing body of research questioning the protective effects of alcohol consumption. Last year, a global study concluded that there is no safe level of alcohol consumption.

In the new study, the researchers analyzed information from a database that contains estimates of alcohol-related deaths and potential years of life lost due to alcohol consumption in the United States. The database includes 54 medical conditions that are related, either directly or indirectly, to alcohol consumption, such as alcoholic liver disease and alcohol-related car crashes. Though alcohol consumption is tied to an increased risk of death from most of these conditions, it's linked with a reduced risk of some others, mainly types of cardiovascular disease.

The study researchers found that from 2006 to 2010, about 36 percent of deaths related to alcohol consumption occurred in people ages 20 to 49, and 35 percent occurred among those ages 65 and older.

In addition, about 60 percent of years of life lost due to alcohol consumption occurred in people ages 20 to 49, compared with just 15 percent in people ages 65 and older.

To look at alcohol's benefits, the researchers focused on deaths that were estimated to be "prevented" by alcohol consumption, as well as years of life "saved" by alcohol. Only 4.5 percent of estimated deaths said to be prevented by alcohol consumption occurred among those ages 20 to 49, compared with 80 percent among those ages 65 and older.

More than 50 percent of the estimated years of life said to be saved occurred among those aged 65 and older, compared with just 14.5 percent of those ages 20 to 49.

Overall, the findings suggest that previous studies that enrolled older adults underestimated alcohol-related risks compared with what would be seen for drinkers of all ages, the researchers said.

Still, the researchers note that "there are many reasons why people choose to drink or not to drink alcohol apart from its health effects" and that most people who choose to drink moderately can do so with relatively low risk.

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Originally published on Live Science.

The adage, "beer before wine and you'll feel fine, wine before beer and you'll feel queer" doesn't hold up to scientific scrutiny. A new study finds that the order in which you consume alcoholic drinks won't actually help you avoid a hangover.

Rather, drinking too much alcohol of any kind — and in any order — will likely give you a hangover, the study researchers conclude.

"We didn't find any truth in the idea that drinking beer before wine gives you a milder hangover than the other way around," lead study author Jöran Köchling, of Witten/Herdecke University in Germany, said in a statement. "The truth is that drinking too much of any alcoholic drink is likely to result in a hangover." [11 Interesting Facts About Hangovers]

The study is published yesterday (Feb. 7) in the American Journal of Clinical Nutrition.

Putting proverbs to the test

There is no medically proven way to prevent or treat a hangover — the symptoms of headache, nausea and fatigue that come with drinking too much alcohol. Instead, people sometimes rely on such unproven folk sayings as "wine before beer"; or "grape or grain but never the twain"; or "beer before liquor, never been sicker." Similar folk wisdom on the ordering of wine and beer exist in other languages, including German and French.

The new study put these proverbs to the test. The researchers recruited 90 healthy volunteers ages 19 to 40 who agreed to down large amounts of alcohol, for science.

The participants were divided into three groups. The first group consumed about two and a half pints of beer (with an alcohol content of 5 percent each) followed by four large glasses of wine (with an alcohol content of 11 percent each). The second group consumed the same amount of alcohol, but in reverse order (wine followed by beer). The third group drank only beer or only wine. During the drinking task, the participants were asked to rate their perceived level of drunkness.

Afterwards, they spent the night at the study site under medical supervision. The next day, participants were asked about their hangover symptoms; and they were given a score based on the number and severity of those symptoms, such as thirst, fatigue, headache, dizziness, nausea, stomach ache, increased heart rate and loss of appetite.

A week later, the participants came back to the study site to perform the drinking task again, but participants in groups one and two were switched to the opposite drinking order. (Those who consumed beer first on the initial visit consumed wine first on the second visit, and vice versa.) Participants in the third group who drank only beer on the first visit drank only wine on the second visit, and vice versa. This way, the researchers could compare the reactions of each individual to the same person's earlier experience. (In other words, each person served as their own "control."

The researchers found that participants in all three groups had similar hangover scores.

"Unfortunately, we found that there was no way to avoid the inevitable hangover just by favouring one order over another," senior study author Dr. Kai Hensel, a senior clinical fellow at the University of Cambridge in the United Kingdom, said in the statement.

Only two factors predicted the severity of a person's hangover: that person's "perceived drunkenness" score and whether the person vomited after the drinking task. (Higher perceived drunkenness scores and vomiting were both tied to more severe hangovers.)

"The only reliable way of predicting how miserable you'll feel the next day is by how drunk you feel and whether you are sick. We should all pay attention to these red flags when drinking," Köchling said.

The researchers note that the study used only lager beer and white wine, so it's unclear if the results apply to other types of alcohol.

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Originally published on Live Science.

There are all sorts of drinking traditions. Some people sing songs as they down their alcohol. Others dance to thumping music. Somewhere in the vicinity of Rotterdam, in the Netherlands, a group of young men, apparently inspired by the American television show "Jackass," got in the habit of capping off their boozing by swallowing live fish.

This, it turns out, is a bad idea. Especially in the event that the fish have evolved to fight back.

According to a recent case report published on Jan. 17 in the journal Acta Oto-Laryngologica Case Reports, the young men typically swallowed live goldfish out of their home aquarium — small, squishy creatures that don't put up much of a fight. The fun stopped on April 3, 2016, when one of the men tried to take their tradition a bit further by swallowing a bronze catfish (Corydoras aeneus), a popular aquarium fish with some powerful natural defenses. [27 Oddest Medical Case Reports]

Perhaps unsurprisingly, the night ended with the 28-year-old man in the emergency room, where puzzled doctors carefully removed the spiny fish from the man's throat.

"Most animals know better"

Most animals know better than to eat bronze catfish, said Kees Moeliker, a director at the Rotterdam Natural History Museum who reviewed the catfish remains after doctors removed them from the man's throat. That's for a good reason: Their cute 2- to 3-inch bodies (5 to 8 centimeters) are defended with spines, mounted on their pectoral fins. When the fish get stressed out — say, for example, when they're being swallowed by a predator — those spines become erect and can pump venom into the mouths of their attackers.

Because of this, bronze catfish "don't have predators like birds and other fishes," Moeliker told Live Science. "Those who give it a try die, and natural selection does its work."

Indeed, in the man's case, it appears that he quickly realized that he had made a grave mistake, according to a video of the incident that was described by the case report authors. Unfortunately, the video was not available for Live Science to review or share. But the report includes a vivid description of what it showed. In the video, a crowd of men stood around drinking and shouting "grote vis, grote vis!" (Dutch for "Big fish! Big fish!") One guy, holding a glass of clear water with the live catfish in it, tips it back, attempting to swallow it whole. Four seconds later, he spit the water and the fish out into his hands, and threw it on the table, where it floundered, appearing "distressed" and "agonized," according to the report.

That might have been the end of it, if someone hadn't plucked the flopping catfish off the table and handed it to a third man, a 28-year-old whose trauma would become the subject of the case report. This unfortunate fellow swallowed some beer, and then dropped the still-living creature into his throat. [11 Weird Things People Have Swallowed]

Immediately, it was obvious something had gone wrong. The man tried to swallow more beer but couldn't. Ten seconds later, he was "gagging vigorously" and vomiting liquid. "In extreme distress," he shoved two fingers down his throat, trying to make himself gag but no luck. Someone administered what the doctors described as a "wrongly-applied Heimlich maneuver," which again failed to produce the fish. The man spewed some blood into a bucket, and then the camera switched off.

Even so, the man apparently waited "several hours" before going to the hospital, after trying but failing to dislodge the fish with "more beer, honey and ice cream."

A "fish-like" structure

When the man finally made it to the emergency room, doctors looked down his throat using a tool called a laryngoscope, and spotted what they described as "a fish-like structure," according to the report. [Photos: The Freakiest-Looking Fish]

"This is definitely in the top three of weirdest medical cases I’ve encountered," said case report co-author Dr. Linda Benoist, a medical resident at Rotterdam’s University Medical Center who treated the patient. Benoist told Live Science that she had been aware that the fish-swallowing game was a "bizarre" tradition among some young people in the area.

The catfish, she said, was already dead when the patient arrived, pressed up against the entrance to the man's esophagus, at the bottom of his throat. (The fish had probably suffocated, Moeliker said, noting that a few swallows of beer do not contain enough water for a fish to breathe in).

The man needed surgery to remove the fish, with the surgeons paying very close attention to carefully remove the fish's spines from the delicate tissue in the throat. .

Fortunately, the procedure was a success. Though not much is known about the effects of bronze catfish venom on humans, it didn't appear to complicate the situation. As of the man's most recent follow-up with doctors, in March 2017, he is doing well.

The fish, meanwhile, ended up preserved at the Rotterdam Natural History Museum, which is right next door to the hospital. It joined an exhibit called "Dead Animal Tales" on dramatic collisions between animals and humans, Moeliker said.

Asked whether the drinking game is dangerous when only goldfish are involved, Benoist said, "I'm not an expert in goldfish swallowers, but I can imagine that fish species without [spikes] would slide easier into the stomach."

Still, the researchers did highlight some other case studies where people choked on live fish, including one instance where a fisherman attempted to kiss a fish but it slid into his throat. Live Science recommends eating fish dead and in bite-size pieces.

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Originally published on Live Science.

Smoking pot just once might be linked to changes in young brains, a new study suggests.

Adolescents who smoked marijuana one or two times had increased amounts of gray matter — a combination of neuron bodies and cells that feed them — in their brains compared with those who hadn't, according to a new study published yesterday (Jan. 14) in the Journal of Neuroscience.

A bigger brain volume may sound like a benefit for adolescents, but it may not be, said lead study author Catherine Orr, a lecturer in the department of psychological sciences at Swinburne University of Technology in Australia. [7 Ways Marijuana May Affect the Brain]

That's because, in adolescence, the brain typically undergoes a process called pruning, Orr said. During this process, which goes on through a person's early 20s, the brain chips away at its existing gray matter, and increases the amount of white matter, which consists of the long tails of neurons called axons that connect cells, and their protective coating called myelin.

Though it’s not absolutely clear why the brain does this, the best explanation to date is that the process makes the brain more efficient, cutting away unnecessary or redundant components, and also makes the brain more complex by building more connections, Orr said.

That's why interfering in the process — by adding more gray matter — could potentially be a bad thing.

Measuring gray matter

In their study, Orr and her team looked at brain scans from 46 teens, all age 14, from Ireland, France, England and Germany. Some reported having smoked marijuana once or twice while others reported never having used the drug at all. The researchers controlled for other factors such as cigarette smoking and alcohol-use that could have also driven these changes.

The study found that those who smoked pot had higher volumes of gray matter in areas of the brain that had cannabinoid receptors, compared with those who reported never using the drug. Compounds in marijuana bond to cannabinoid receptors, which are found in areas including the amygdala (which is involved in emotion and threat processing), the hippocampus (which is involved in memory and learning), and the nucleus accumbens (which is involved in reward and addiction).

The researchers also found that those who had increased gray matter in their brains also had lower perceptual reasoning and a lower ability to perform a task quickly than those with normal levels of gray matter

"I personally was surprised at how extensive the effects were," Orr told Live Science.

Previous studies had found marijuana affects similar areas of the brain, however, these studies have had inconsistent results. For example, some studies in adults have found that marijuana-use was linked to an increase in gray matter, while others found the opposite. Orr noted that because these earlier mostly looked at adult brains, it's difficult to untangle the potential effects of other substances such as alcohol.

Even so, increasing evidence shows that adults that use marijuana at higher rates or for longer amounts of time or those who started earlier in life showed greater changes in the brain, she said.

Still, Orr said that more research is needed to say for sure what the effects of marijuana are on the brain. The small sample size of the study makes it difficult to disentangle the effects that other activities may also have on the brain, she added.

It's also unclear whether these changes in the brain are long-lasting, Orr said, adding that it would be good to do a follow-up study to explore this question. Ultimately, the researchers hope to be able to "identify which people are more at risk of these brain-based effects and [let] people know what [these effects] are," Orr said.

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Originally published on Live Science.

It may sound counterintuitive, but people who are supersensitive to coffee's bitter taste actually drink more of it, a new study finds.

This sensitivity isn't simply a matter of taste, either, but rather is influenced by a person's genetic makeup, the researchers said in the study, which was published online today (Nov. 15) in the journal Scientific Reports.

"You'd expect that people who are particularly sensitive to the bitter taste of caffeine would drink less coffee," study senior researcher Marilyn Cornelis, an assistant professor of preventive medicine at the Northwestern University Feinberg School of Medicine in Chicago, said in a statement. "The opposite results of our study suggest coffee consumers acquire a taste [for] or an ability to detect [the bitterness of] caffeine due to the learned positive reinforcement elicited by caffeine." [10 Things You Need to Know About Coffee]

Put another way, people who have a heightened ability to taste the bitterness of coffee, and especially the distinct bitter flavor of caffeine, learn to associate "good things with it," Cornelis said. This finding is surprising, given that bitterness often serves as a warning mechanism to convince people to spit out harmful substances, the scientists said.

Researchers conducted the study to understand how genetics influences people's consumption of tea, coffee and alcohol, which tend to taste bitter, said lead study researcher Jue Sheng Ong, a doctoral student in the Department of Genetics and Computational Biology at the QIMR Berghofer Medical Research Institute in Brisbane, Australia.

"While all bitter flavors might seem the same, we perceive the bitterness of Brussels sprouts, tonic water (quinine) and caffeine separately," Ong told Live Science. "The degree to which we find these flavors bitter is, in part, determined by your genes."

To investigate, the researchers looked at the genetic makeup and daily bitter-beverage consumption of more than 400,000 people from the United Kingdom. "Using the genes related to our ability to taste bitterness, we were able to assess whether those that have a higher genetic predisposition to tasting bitterness are more likely to prefer tea over coffee," Ong said.

The results showed that people with the genes to taste the bitterness of green vegetables (such as Brussels sprouts) or tonic water are more likely to prefer tea over coffee, the researchers found. In addition, people who were more sensitive to quinine's bitter flavors and those found in green vegetables tended to avoid coffee.

Meanwhile, people with the genes to taste the bitterness in Brussel sprouts were less likely to drink alcohol, especially red wine, than people without those gene variants, the researchers found. This insight may help scientists studying addiction, Ong said.

Ong noted that the researchers didn't look at flavorings, such as cream or sugar, that people sometimes pour into coffee to temper its bitterness. "One can imagine that, at a personal level, there are a lot of factors that determine a person’s coffee intake — socioeconomic status, ability to metabolize caffeine and smoking," he said. "On top of that, people drink all sorts of coffee — black coffee, flat white [and] cappuccino." So, the researchers chose to look for big trends in how genes relate to bitter-beverage consumption, he said.

"[The results] suggest that perhaps most types of coffee still share very similar bitter-taste profiles," Ong said.

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Originally published on Live Science.

The world's oldest beer may have been brewed for a funeral 13,000 years ago.

At a graveyard cave in Israel, archaeologists discovered traces of mashed wheat and barley lining pits carved into the bedrock. The researchers interpreted these residues as leftovers from beer brewing, perhaps part of a funerary feast.

"This accounts for the oldest record of man-made alcohol in the world," Li Liu, a professor of Chinese archaeology at Stanford University, said in a news release.

Liu's team had been trying to learn about ancient diets from plant residues on the stone pits found in the Raqefet Cave, a Natufian grave site near Haifa, Israel. [Raise Your Glass: 10 Intoxicating Beer Facts]

The Natufians were a Stone Age culture that lived in the Near East from around 15,000 to 11,500 years ago. They established some of the earliest settlements in the world and may have been among the earliest people to domesticate plants and animals.

At Raqefet Cave, Liu's team collected residue samples from the stone pits, or mortars that had been dug into the cave. Under a microscope, they saw damaged-looking starch granules, thought to be from wheat or barley that was malted and mashed during beer brewing.

To test this hypothesis, the researchers conducted experiments to look at how starch granules transformed during the brewing process. To re-create Natufian-style beer, they turned barley into malt, which they mashed and heated and left to ferment with yeast. Under the microscope, the modern starch granules matched the ones found at Raqefet Cave, Liu and her colleagues reported in the Journal of Archaeological Science: Reports.

"I thought [the study] was pretty exemplary in terms of the procedures and techniques," said Brian Hayden, an archaeologist at Simon Fraser University in Canada who was not involved in the study, but reviewed the paper before publication. "They show that in the brewing process, the starch grains undergo some morphological changes."

Hayden told Live Science that there has been considerable debate among archaeologists about the nature of the Natufian culture and other complex hunters and gathers of the same period. He's argued that this was a society with surpluses, wealth, social inequality and extensive trade networks —and finding evidence for brewing helps support that point of view.

"Brewing by itself indicates that this is a society with surpluses," Hayden told Live Science. "A lot of the residual material from brewing is discarded."

He added that there is evidence for feasting in the Natufian culture, and ethnographic evidence suggests that feasting for many traditional societies involves making alcohol.

"We were predicting that eventually somebody would find the smoking brew pot and demonstrate that there was brewing in the Natufian," Hayden said.

Pat McGovern, a biomolecular archaeologist at the University of Pennsylvania Museum of Archaeology and Anthropology, has also been waiting for evidence of alcohol consumption from the Paleolithic period, or Old Stone Age, which he calls the "Holy Grail" in his book "Ancient Brews" (W. W. Norton & Co., 2017).

"The earliest evidence we had for ancient beverages until now was from the Neolithic period," McGovern told Live Science. "I believe that this article is on the right track in finding out more about fermented beverages during 99 percent of humankind's history, dating back millions of years."

McGovern does, however, think the starch analysis could be strengthened by further chemical and pollen studies. "It would be good to have additional verification by different methods of the ingredients that were used, and of the mashing or fermentation process," he said. "I'm not totally convinced, but I think it was highly probable that people were making a fermented beverage in this period, and that it was used for religious burial practices."

The findings at Raqefet Cave might also add to the debate over whether a thirst for beer or a hunger for bread may have driven people to domesticate grain. In July, another group of archaeologists working at a Natufian site in east Jordan reported that they found the earliest evidence of bread making — 14,000-year-old traces of charred flatbread made from wild grain.

Original article on Live Science.

We all know we shouldn't drink and drive. But what about hopping behind the wheel the morning after you've been drinking? According to a new meta-analysis, even this could be problematic, as the effects of alcohol on our brains may linger even after the chemical has left our bloodstream.

The meta-analysis, which was published Aug. 25 in the journal Addiction, found that a night of heavy drinking may affect people's cognition the next day, including their memory, attention, coordination and even driving skills.

"Our findings demonstrate that [having a] hangover can have serious consequences for the performance of everyday activities such as driving, and workplace skills such as concentration and memory," senior study author Sally Adams, an assistant professor in the Department of Psychology at the University of Bath, in the United Kingdom, said in a statement.

Thinking after drinking

It's well-known that drinking alcohol can temporarily impair thinking and coordination while a person is intoxicated. But whether drinking alcohol impairs cognition the next day — i.e., when a person is  hungover — is less clear, with studies on the topic finding conflicting results. [11 Interesting Facts About Hangovers]

In the meta-analysis, the researchers analyzed data from 19 previous studies involving more than 1,100 people. All of the studies tested people's thinking abilities the day after they had drunk heavily, when their blood-alcohol level was less than 0.02 percent. (For comparison, the legal blood-alcohol limit for driving a car in the United States is 0.08 percent.)

Some of the studies were conducted in a laboratory — meaning that researchers gave people precise amounts of alcohol before testing their thinking abilities; other studies were "naturalistic," meaning that researchers told people to come to the lab after a typical night of social drinking.

The study found that, overall, people who were hungover had poorer attention, memory and coordination skills, compared with those who weren't hungover. A few of the studies tested people's driving ability using a driving simulation. The studies found that when people were hungover, their ability to control a vehicle was impaired, compared with when they were not hungover.

Although many people think that it's fine to drive the morning after a night of drinking, "it might be that we're still impaired the next day, even after the alcohol has left our system," Adams said.

Overall, the findings suggest that "some of the things that you might expect to happen with your thought processes on alcohol may continue throughout into the hangover period," said lead author Craig Gunn, also of the University of Bath's Department of Psychology. This means that if you're a student attending a lecture, you might not be able to remember things as well when you're hungover, compared with when you're not hungover, Gunn said. And if you're driving a car, you might not be able to react as efficiently to a red light, he said.

Still, the researchers noted that some of the studies did not take into account other factors that could affect thinking abilities, such as smoking or sleep deprivation. The researchers called for further studies testing the effects of alcohol on cognition, particularly on people's "executive functions," which include decision-making and problem solving.

More research is also needed on the effect of hangovers on workplace safety and productivity, the researchers said. They noted that although many workplaces have policies prohibiting intoxication on the job, few of these policies cover the next-day effects of alcohol.

Original article on Live Science.

Drinking alcohol in moderation is more harmful than previously thought, according to a new study that concludes there's no "safe" level of alcohol consumption.

The comprehensive study, which analyzed information from millions of people in nearly 200 countries, found that alcohol is tied to nearly 3 million deaths globally each year, with about 1 in 10 deaths linked to alcohol use among people ages 15 to 49.

What's more, any protective health effects of alcohol were offset by the drink's risk, including strong links between alcohol consumption and the risk of cancer and injuries such as those resulting from car accidents. [7 Ways Alcohol Affects Your Health]

"The widely held view of the health benefits of alcohol needs revising," the researchers wrote in their paper, published online Aug. 23 in the journal The Lancet. "Our results show that the safest level of drinking is none."

The findings contrast with most health guidelines, which say that moderate drinking — about one drink a day for women and two for men — is safe.

However, it's difficult to estimate the risks for a person who drinks fairly infrequently — such as someone who has one drink every two weeks — so the findings might not apply to this population. "[It] doesn't mean, if you drink on birthdays and Christmas, you're going to die," said Keith Humphreys, a professor of psychiatry and behavioral sciences at Stanford University who was not involved in the study.  

Rather, the findings apply more to people who have one drink a day, most days of the week, Humphreys said. Contrary to what some previous studies have found, "the kind of person who drinks every week, but never drinks much, is in fact not better off than somebody who doesn't drink," according to the new study, Humphreys told Live Science.

No "safe" level

The study analyzed information from nearly 700 previous studies to estimate how common drinking alcohol is worldwide, and examined almost another 600 studies including a total of 28 million people to investigate the health risks tied to alcohol.

The researchers found that, globally, about 1 in 3 people (32.5 percent) drink alcohol, which is equivalent to 2.4 billion people worldwide, including 25 percent of women and 39 percent of men.

Worldwide, drinking alcohol was the seventh-leading risk factor for early death in 2016, accounting for about 2 percent of deaths in women and 7 percent of deaths in men. For people ages 15 to 49, alcohol consumption was tied to 4 percent of deaths for women and 12 percent for men in 2016.

The study found that moderate drinking was, in fact, protective against ischemic heart disease. But this benefit was outweighed by the health risks of alcohol.

Specifically, for people who consume one drink a day, the risk of developing one of 23 alcohol-related health problems increases by 0.5 percent over one year, compared with someone who doesn't drink.

But the risk increases rapidly the more people drink. For people who consume two drinks a day, the risk of developing one of the 23 alcohol-related health problems increases by 7 percent over one year, and for those who drink five drinks a day, the risk increases by 37 percent over one year. [Top 10 Leading Causes of Death]

"Alcohol poses dire ramifications for future population health in the absence of policy action today," Emmanuela Gakidou, a professor of global health at the University of Washington's Institute for Health Metrics and Evaluation and a co-author of the study, said in a statement.

The researchers said that, based on their results, public health campaigns should consider recommending abstinence from alcohol.

Alcohol abstinence?

Humphreys called the work the "most sophisticated global study of the impact of alcohol on human health ever conducted."

"The study confirms that alcohol is one of the world's leading causes of disability, disease and death," Humphreys said.

However, in terms of recommending abstinence from alcohol, Humphreys said that promoting such a message would be difficult, in part because of the large number of people who currently drink alcohol and the influence of powerful industries in the alcohol market. "I'm not saying it's a terrible idea," Humphreys said, but "it would be a very tough uphill battle to be established."

Still, in addition to considering abstinence, the researchers called for other policies that focus on reducing the population's consumption of alcohol, such as increasing alcohol taxes, controlling the availability of alcohol and the hours it can be sold, and regulating alcohol advertising. "Any of these policy actions would contribute to reductions in population-level consumption, a vital step toward decreasing the health loss associated with alcohol use," Gakidou said.

The study was funded by the Bill & Melinda Gates Foundation.

Original article on Live Science.

If the thought of sipping a beer is gag-inducing, you're not alone. But even if you're in good company, it begs the question: Why do some people hate the taste of beer?

The answer comes down to genetics, which influences how our brains process bitter-tasting and cold beverages.

What's more, it turns out that beer's bitter taste triggers evolutionary wiring designed to keep us away from potentially dangerous food and drink, and this trigger is stronger in some people than it is in others. [Is Booze Tasty or Bitter? Your Genes Decide]

But first, let's start with beer's bitter taste. As you may remember from science class, there are five types of taste cells within our taste buds that help us perceive salty, sweet, sour, umami (savory) and bitter flavors. Once the taste buds identify specific flavors, taste receptors send this data via nerves to the brain stem.

"If you think of a receptor as a lock, then whatever it binds to is a specific key," Dr. Virginia Utermohlen Lovelace, an associate professor emeritus of nutritional sciences at Cornell University in Ithaca, New York, told Live Science. "The cell to which that receptor is attached sends a message to the brain to say, 'Oooh this is bitter!'"

There are a whopping 25 different types of taste receptors for bitterness in the human body. In comparison, there are only two different kinds of salt receptors. Meanwhile, beer's bitterness largely comes from hops. The alpha and beta acids found in hops, as well as the low concentrations of ethanol in beer, bind to three of these 25 bitter receptors, signaling a strong bitter taste to the brain when you take a sip of lager, Lovelace said.

But what makes bitter flavors hard to swallow? The next time your friends delight in introducing you to a new craft IPA, you can tell them that their singular tastes are in direct opposition to evolutionary instinct. Humans actually evolved bitter taste receptors for our own safety — to identify poisonous foods that could be harmful.

"Bitter taste is considered a warning system for poisoning," researchers in a 2009 study published in the journal Chemosensory Perception concluded. "Many toxic compounds appear to taste bitter; yet, toxicity seems not to be directly correlated with the taste threshold concentrations of bitter compounds," the researchers said.

In other words, just because something tastes bitter and makes you wince, that doesn't automatically mean that beer (or any other bitter food or beverage) is out to kill you.

This brings us to the science behind genetic functional polymorphisms, also known as genetic variations. Since there are so many taste receptors for bitterness, it's safe to say that bitter flavors — how we perceive them and how much we can tolerate them — have a plethora of inheritable genetic possibilities.  

According to a 2017 study published in the journal Scientific Reports, TAS2R16 alone (which is one of the 25 bitter receptors in the human body) has 17 polymorphisms, including a variant that is associated with alcohol dependence.

Lovelace explained that one of the easiest indicators of bitter sensitivity is the number of taste buds you have in your mouth. The more taste buds you have, the more likely you are to detest hoppy beers.

Bitter receptors, however, are not the only variants at play. The carbonation in beer turns on our "cold" receptors (the same temperature receptors that make minty gum taste cold and cinnamon taste hot). Cold receptors have genetic variations too, so while you may not be sensitive to the bitterness of beer, the receptors that signal coldness might also make beer seem unappealing, Lovelace said.

If you're sensitive to the bitterness in beer or other alcohol, there are countermeasures to help "drown out" the strength of the bitter receptors, she noted.

"Sweet and salty foods can help turn off the effects of the bitter receptors, which is why we have beer nuts and why we drink tequila with salt!" Lovelace said. "When you cut away the bitter, you're more likely to receive the specifics of the flavors underneath."

Original article on Live Science.

Drinking less alcohol may be linked to a lower risk of cancer, a new study suggests.

In the study, researchers found that people who drank some alcohol had a lower risk of cancer and death from any cause during a nine-year period than those who drank more or none.

In particular, people who had fewer than seven drinks a week had the lowest risk of cancer and death, compared with those who had seven or more drinks a week, according to the study, published today (June 19) in the journal PLOS Medicine. And with each additional drink a week, the risk of cancer and death from any cause increased, the scientists reported.

However, the study found only an association between alcohol and cancer and death, and did not prove cause and effect, the researchers said.

What sets the new study apart, said lead study author Andrew Kunzmann, a postdoctoral research fellow at Queen's University Belfast in Ireland, is that previous studies have tended to look at cancer and mortality separately. [7 Ways Alcohol Affects Your Health]

"That tends to give very different messages about what the role of alcohol and health is," Kunzmann told Live Science. Most existing evidence suggests that light-to-moderate drinkers had the lowest risk of dying from various causes during the study period, yet "never drinkers" had the lowest risk of developing cancer, he said.

"What our study does is combine the two outcomes together and [finds] that lighter drinking is associated with the lowest risk of cancer or death," Kunzmann said. And those who had no drinks or more than one drink a day were more at risk for death or cancers, most commonly esophageal and liver cancer and cancers of the head or neck regions, Kunzmann said.

In the study, the team analyzed data about lifetime alcohol use from questionnaires that were given to the nearly 100,000 participants in the United States between 1998 and 2000. The questionnaires were given at the beginning of the study and asked how many drinks a person had a week at present and with what frequency over the previous year. The researchers also looked at data on the number of primary cancer diagnoses (meaning it was the first time the person had been diagnosed with cancer) and deaths that occurred in the cohort over the next nine years.

"The study results suggest that minimizing alcohol intake may help individuals who already drink to lower their risk of developing certain types of cancer, such as breast, colorectal and liver cancer," Kunzmann said in a statement. "The results perhaps also suggest that [decisions about] drinking that second glass each night shouldn't be made for health reasons."

But Kunzmann noted that the participants were all older adults. That means that "we're not really reflecting what happens in younger people if they drink," he said. Also, it's difficult to account for other lifestyle factors that could have affected the results.

"Light drinkers tend to be more wealthy or lead healthier lifestyles in a number of ways than never drinkers," he said, and these factors could also influence health. But the results did take into consideration differences in diet, smoking and education among participants, Kunzmann noted.

In general, most people agree that "if you drink alcohol, drinking less reduces your risk" of health problems, including cancer," said Dr. Timothy Naimi, an alcohol epidemiologist at Boston Medical Center who was not involved with the study. But there could be other factors that "may make light drinkers 'appear' to be better off statistically, because they are socially advantaged," he told Live Science.

The researchers said that they hope their study sparks conversation about reducing the recommended alcohol intake in countries' guidelines. The U.K. guidelines, for example, recommend that both men and women should have fewer than six drinks a week (less than one drink a day), whereas the U.S. guidelines state that men shouldn't have more than two drinks a day and women no more than one, according to Kunzmann.

However, public health guidelines take into account many more factors than the study authors did, Kunzmann said. And the team cautioned that nobody really knows why light drinking might have a benefit such as cardiovascular protection or even if the results are caused by unrelated factors such as being more health-conscious.

"We're not telling people what they can or can't do or what they can or can't drink," Kunzmann said. "We're just trying to give them reliable evidence so that they can make their own informed, healthy decisions."

Originally published on Live Science.

You've probably heard of the brain's reward network. It's activated by basic needs — including food, water and sex — and releases a surge of the feel-good neurotransmitter dopamine when those needs are met. But it can also be hijacked by drugs, which lead to a greater dopamine release than those basic needs.

But the reward network isn't the only brain network altered by drug use. A new review concluded that drug addiction affects six main brain networks: the reward, habit, salience, executive, memory and self-directed networks.

In 2016, a total of 20.1 million people ages 12 and older in the U.S. had a substance-use disorder, according to the National Survey on Drug Use and Health, an annual survey on drug use. And drug addiction, regardless of the substance used, had surprisingly similar effects on the addicted brain, said the new review, published yesterday (June 6) in the journal Neuron.

The review looked at more than 100 studies and review papers on drug addiction, all of which studied a type of brain scan called functional magnetic resonance imaging (fMRI).

More than half of the studies out there look at the effects of drug use on the reward network, said Anna Zilverstand, lead author of the new review and an assistant professor of psychiatry at the Icahn School of Medicine at Mount Sinai in New York City. [7 Ways Alcohol Affects Your Health]

"Because we showed that the effects are very distributed across the six different networks … [we can conclude that] an approach that only looks at one of these networks isn't really justified," Zilverstand told Live Science. "This [finding] will hopefully lead other researchers to look beyond the reward network."

For example, the memory network is pretty much ignored in research on substance-use disorders, Zilverstand said. This network allows humans to learn non-habit-based things, such as a new physics concept or a history lesson. Some research has suggested that in people with substance-use disorders, stress shifts the person's learning and memory away from the memory network to the habit network, which drives automatic behavior, such as seeking and taking drugs.

Another less-studied network is the self-directed network, which is involved in self-awareness and self-reflection, the review said. In people with addictions, this network has been associated with increasing craving.

Two other networks are involved in substance-use disorders: The executive network is normally responsible for goal-maintaining and execution, but drugs can alter this network as well, reducing a person's ability to inhibit their actions. The salience network picks up important cues in a person's environment and redirects the individual's attention to them. (In people with drug addiction, attention is redirected toward drugs, increasing craving and drug-seeking.)

Which comes first, the brain activity or the drug use?

"For me, the most surprising [finding] was how consistent the effects were across addictions," Zilverstand said. What's more, "the fact that the effects are quite independent of the specific drug use points to them being something general that might actually precede drug use rather than be a consequence of drug use."

Zilverstand said she hopes that more studies will look at whether some people have abnormal brain activity in these six networks naturally and if that activity just gets exacerbated if they begin drug use. It's important to know if some of these traits precede drug use; if that's the case, it might be possible to identify people who are prone to addiction and intervene before an addiction begins, she said.

Some research has pointed toward this possibility already. For example, studies have shown that some people have "difficulties … inhibiting impulsiveness before drug use," Zilverstand said. "Some of these impairments precede drug use, and they may become worse with more drug use, but they exist before the problem escalates."

The good news, however, is that activity in four of these networks — executive, reward, memory and salience — moves back toward "normal" once drug use ends. "We know that four of the networks (partially — not fully) recover but not yet what happens to the other two networks," Zilverstand said in an email.

Zilverstand added that she's particularly excited about an ongoing study called the Adolescent Brain Cognitive Development (ABCD) Study, which is tracking 10,000 children across the U.S. from around ages 9 or 10 to age 20 (the children are now around 13). Some of these individuals will inevitably become addicted to drugs, most likely marijuana or alcohol, Zilverstand said.

"We'll be able to see if the effects that we found [in the review] exist in youth who have not yet abused drugs," she said, and she predicted that researchers will be able to find a lot of the effects identified in the review in the six brain networks.

The authors noted that because some regions of the brain are very small — for example, the amygdala, which is found toward the center of the brain — the studies can't identify strong signals from those areas on brain scans. So, it's possible that drugs affect additional networks in the brain that are hidden because of the limitations of our technologies, Zilverstand said.

"We don't want to conclude that [those effects] don't exist," she said.

Originally published on Live Science.

Worldwide, alcohol and tobacco cause much more death, disability and addiction than illegal drugs, according to a new review.

The review analyzed data from 2015 on global drug use — both overall and in 21 different regions — using data from the World Health Organization, the United Nations Office on Drugs and Crime, and the Institute for Health Metrics and Evaluation, as well as other sources. The researchers examined both the prevalence of drug use as well as the "health burden," in the form of death and disability tied to drugs.

The researchers found that, worldwide, an estimated 18 percent of people reported "heavy" alcohol use in the last month (heavy use corresponds to more than 60 grams of alcohol, or about four standard drinks, on one occasion). In addition, 15 percent reported daily tobacco smoking, 3.8 percent reported marijuana use in the past year, 0.77 percent reported amphetamine use in the past year, 0.37 percent reported non-medical opioid use in the past year and 0.35 percent reported cocaine use in the past year.

Some of the highest levels of alcohol consumption were in Central, Eastern and Western Europe, where the per-capita consumption was 11 to 12 liters (about 3 gallons) of pure alcohol a year, compared with about 6 liters (1.5 gallons) a year per capita worldwide. These regions also had the highest levels of daily tobacco smoking, with around 21 to 24 percent of those populations reporting daily smoking, according to the review. [Here's How Much Alcohol Is OK to Drink in 19 Countries]

Regarding addiction, an estimated 63 million people worldwide were dependent on alcohol in 2015, with about 843 cases of  alcohol dependence per 100,000 people. For comparison, about 20 million people were dependent on marijuana (260 cases per 100,000 people) and 17 million were dependent on opioids (220 cases per 100,000 people) in 2015.

However, the rates of marijuana and opioid dependence were almost threefold higher in the United States and Canada (a region called "high-income North America" in the report) than in the rest of the world, with an estimated 749 cases of marijuana dependence and 650 cases of opioid dependence per 100,000 people.

Tobacco smoking was tied to the greatest rate of death. For every 100,000 deaths in 2015, 110 were tied to tobacco, while just 33 were related to alcohol and seven to illegal drug use.

The researchers also calculated how many years of life were lost by people who died from drug use, or who were living with disability from drug use (which together were called "disability-adjusted life years," or DALYs). They found that tobacco smoking cost the human population 171 million DALYs, compared with 85 million DALYs for alcohol and 28 million DALYs for illegal drug use.

"Alcohol use and tobacco smoking are far more prevalent than illicit substance use, globally and in most regions," the researchers wrote in the May 11 issue of the journal Addiction.

And tobacco smoking accounted for most of the health burden due to drugs, they said. Still, the health toll of illegal drugs may be underestimated because available data on these drugs is limited.

For example, some countries and regions (including Africa, the Caribbean, Latin America and Asia) have little or no data on substance use and its associated health burden, the researchers said.

"Better standardized and rigorous methods for data collection, collation and reporting are needed to assess more accurately" the disease burden from substance use worldwide," the researchers said.

Original article on Live Science.

Drinking alcohol may increase women's risk for premenstrual syndrome, or PMS, a new meta-analysis from researchers in Spain suggests.

However, the review found only an association between drinking alcohol and PMS and didn't prove that drinking causes PMS or makes symptoms worse, the researchers said.

PMS is a group of symptoms that start about one or two weeks before a woman's period, according to the National Institutes of Health. Symptoms can include mood swings, tender breasts, food cravings, fatigue, irritability and depression. It's estimated that 20 percent to 40 percent of U.S. women experience moderate PMS symptoms and 3 percent to 8 percent experience severe symptoms, according to the review.

Some studies have found that PMS symptoms tend to be more severe among women who drink alcohol, but it's unclear whether this is due to the alcohol itself or if some women drink to cope with PMS symptoms, the researchers said. [7 Ways Alcohol Affects Your Health]

The new meta-analysis, from researchers at the University of Santiago de Compostela in Spain, analyzed information from 19 previous studies in eight countries involving more than 47,000 participants in total.

The researchers found that drinking alcohol was linked with a 45 percent increase in the risk of PMS and that heavy drinking — or consuming more than one alcoholic drink a day — was linked with a 79 percent increase in the risk of PMS.

The relatively large number of studies included in the meta-analysis and the consistency of the results suggest that alcohol intake may increase the risk of PMS, the researchers said.

However, this link could still be due to reverse causation — that is, researchers may be finding an association because women with PMS are drinking to cope with symptoms, said Elizabeth Bertone-Johnson, a professor of epidemiology at the University of Massachusetts Amherst, who studies premenstrual syndrome.

"I think it's really premature to link alcohol to worsening of premenstrual syndrome symptoms … based on this study," said Bertone-Johnson, who wasn't involved in the new analysis.

Nearly all of the studies included in the meta-analysis were retrospective, meaning that the women included in the studies already had PMS when they were asked about their alcohol intake, Bertone-Johnson noted.

"That, unfortunately leaves the possibility that their menstrual symptoms themselves led them to drink alcohol," Bertone-Johnson told Live Science.

To better understand this link, more studies are needed that start tracking women in their teenage years and follow them over time to look at alcohol intake and the development of PMS, she said.

Still, if women want to cut down on alcohol and see if it improves their PMS symptoms, "that's very reasonable," Bertone-Johnson said. But, scientifically, it's unclear if reducing alcohol intake will improve PMS symptoms in the majority of women, she added.

The new study was published today (April 23) in the journal BMJ Open.

Original article on Live Science.

U.S. drinking guidelines are too boozy, according to a new study.

The research, which analyzed data from nearly 600,000 people in 19 countries, found that drinking more than 100 grams of pure alcohol per week (the equivalent of about seven standard drinks in the United States) was linked to an increased risk of early death during the study period.

But many countries have drinking guidelines that consider 100 grams of alcohol a week to be well within the range of "safe" drinking. For example, U.S. guidelines recommend that men drink no more than 196 grams per week, or 14 standard drinks. (For women, U.S. guidelines fall within these recommended amounts, at no more than 98 grams a week.) In Canada, guidelines recommend no more than 136 grams per week for women, and no more than 204 grams per week for men.

In the new study, published yesterday (April 12) in the journal The Lancet, researchers concluded that drinking guidelines should be lowered to a limit of 100 grams a week.  [Here's How Much Alcohol Is OK to Drink in 19 Countries]

"This study has shown that drinking alcohol at levels which were believed to be safe is actually linked with lower life expectancy," as well as other health problems, study co-author Dr. Dan G. Blazer II, a professor emeritus of psychiatry at Duke University, said in a statement. The study's findings are in line with new recommendations for safe drinking in the United Kingdom, which recommend no more than six standard U.K. drinks a week for men and women.

Researchers have previously found that drinking guidelines vary widely around the world. For that reason, it's a little unclear exactly how much alcohol is "safe" to drink; in other words, it's hard to tell what level is associated with a low risk of health problems and substance disorders.

For the new study, the researchers analyzed information from 599,912 people in high-income countries who drank alcohol but did not have heart disease at the study's start. The median follow-up period was 7.5 years.

About half the people in the study reported drinking more than 100 grams of alcohol per week, and 8 percent drank more than 350 grams per week.

Drinking more than 100 grams of alcohol per week was linked with a lower life expectancy. For example, life expectancy was 6 months lower among those who drank 100 to 200 grams per week, and life expectancy was 1 to 2 years lower among those who drank 200 to 300 grams per week, compared with those who drank less than 100 grams a week. The highest level of drinking in the study — more than 350 grams per week — was linked with a 4- to 5-year reduction in life expectancy.

The study also found that alcohol consumption was linked with an increased risk of stroke or heart failure, as well as an increased risk of death from hypertensive disease (high blood pressure) or an aortic aneurysm. There was no clear threshold below which alcohol consumption stopped being associated with these conditions, the researchers said.

In contrast to those findings, alcohol consumption was also linked with a slightly lower risk of nonfatal heart attack. This slightly lower risk of heart attack tied to alcohol consumption must be balanced against the other "serious, and potentially fatal, cardiovascular diseases" linked with alcohol consumption, lead study author Dr. Angela Wood, a lecturer in biostatistics at the University of Cambridge in the United Kingdom, said in the statement.

Overall, the public health message of the study is "if you already drink alcohol, drinking less may help you live longer and lower your risk of several cardiovascular conditions," Wood said.

The researchers noted that the study tracked people's alcohol consumption for at least a year but did not examine the effect of alcohol consumption over a person's entire lifetime. They also noted that the study was not able to account for people who reduced their alcohol consumption due to health complications.

Original article on Live Science.