Often called a "miracle food" and a "nutritional powerhouse," an apple a day really may keep the doctor away as they're one of the healthiest foods a person can eat. These round and juicy fruits are high in fiber and vitamin C, and they are also low in calories, have only a trace of sodium, and no fat or cholesterol.
"Apples are high in polyphenols, which function as antioxidants,” said Laura Flores, a nutritionist based in San Diego. “These polyphenols are found in both the skin of the apples as well as in the meat, so to get the greatest amount of benefits, eat the skin of the apple."
All of these benefits mean that apples may mitigate the effects of asthma and Alzheimer's disease, while assisting with weight management, bone health, pulmonary function and gastrointestinal protection.
Here are the nutritional facts from the U.S. Food and Drug Administration, which regulates food labeling through the National Labeling and Education Act:
*Percent Daily Values (%DV)
|Amt per Serving||%DV*||Amt per Serving||%DV*|
|Total Fat 0g||0%||Total Carbohydrate 34g||11%|
|Cholesterol 0mg||0%||Dietary Fiber 5g||20%|
|Sodium 0mg||0%||Sugars 25g|
|Potassium 260mg||7%||Protein 1g|
Apples are loaded with vitamin C, especially in the skins, which are also full of fiber, Flores said. Apples contain insoluble fiber, which is the type of fiber that doesn't absorb water. It provides bulk in the intestinal tract and helps food move quickly through the digestive system, according to Medline Plus.
In addition to digestion-aiding insoluble fiber, apples have soluble fiber, such as pectin. This nutrient helps prevent cholesterol from building up in the lining of blood vessels, which, in turn, helps prevent atherosclerosis and heart disease. In a 2011 study, women who ate about 75 grams (2.6 ounces, or about one-third of a cup) of dried apples every day for six months had a 23 percent decrease in bad LDL cholesterol, said study researcher Bahram H. Arjmandi, a professor and chair of the department of nutrition at Florida State University. Additionally, the women's levels of good HDL cholesterol increased by about 4 percent, according to the study.
When it comes to polyphenols and antioxidants, Flores explained that they "work in the cell lining to decrease oxidation resulting in lowering risk of cardiovascular disease." A 2017 article published in Trends in Food Science & Technology adds that blood pressure may also be reduced in those with or at risk of hypertension, which also lowers the risk of cardiovascular disease. A decreased risk of Type 2 diabetes, which can also lead to cardiovascular disease, was found in a study of more than 38,000 women and was also attributed to certain polyphenols and the high-fiber content of apples.
There may be respiratory benefits to eating apples, as well. "Apples' antioxidant benefits can help lower the risk of asthma,” Flores told Live Science. A 2017 study published in the journal Nutrients indicates that the antioxidants in a variety of fruits and vegetables, including apples, potentially decrease the risk of asthma by helping control the release of free radicals from inflamed cells in the airways and in the oxygen-rich blood coming from the heart.
"Eating apples in excess will not cause many side effects," Flores said. "But as with anything eaten in excess, apples may contribute to weight gain."
Furthermore, apples are acidic, and the juice may damage tooth enamel. A study published in 2011 in the Journal of Dentistry found that eating apples could be up to four times more damaging to teeth than carbonated drinks.
However, according to the lead researcher, David Bartlett, head of prosthodontics at the Dental Institute at King's College in London, "It is not only about what we eat, but how we eat it." Many people eat apples slowly, which increases the likelihood that acids will damage tooth enamel.
"Snacking on acidic foods throughout the day is the most damaging, while eating them at meal times is much safer," Bartlett said in a statement from King's College. "An apple a day is good, but taking all day to eat the apple can damage teeth."
Dentists recommend cutting up apples and chewing them with the back teeth. They also recommend rinsing the mouth with water to help wash away the acid and sugars.
Apples and pesticides
"Most apples will have pesticides on them, unless they are certified organic," Flores said. In 2018, the Environmental Working Group, a nonprofit environment and human health organization, concluded that 98 percent of conventional apples had pesticide residue on their peels. However, the group also said that "the health benefits of a diet rich in fruits and vegetables outweigh the risks of pesticide exposure." [Infographic: Guide to Pesticides in Produce]
Washing apples well helps remove pesticides, according to the Colorado State University Extension Service. "Washing apples and making sure you rub the skin in some way will do the trick," Flores said. "You can do this with your hands or a fruit scrubber." However, using chemical rinses and other treatments for washing fresh produce is not recommended because the Food and Drug Administration has not evaluated those products for safety or effectiveness.
Some researchers say not to worry about pesticides. Dr. Dianne Hyson, a research dietitian at the University of California, Davis, writes that laboratory tests have shown very low levels of pesticide residue on apple skins.
Are apple seeds poisonous?
Apple seeds, also called pips, contain a chemical compound called amygdalin, which can release cyanide, a powerful poison, when it comes into contact with digestive enzymes. Whole seeds pass through your digestive system relatively untouched, but if you chew the seeds you may be exposed to the toxins. One or two will not be harmful, as the body can handle small doses of cyanide, but if you or a child chews and swallows a lot of seeds, you should seek medical attention immediately.
How many seeds are harmful? According to John Fry, a consultant in food science, about 1 milligram of cyanide per kilogram of body weight will kill an adult person. Apple seeds contain about 700 mg (0.02 ounces) of cyanide per kilogram; so about 100 grams (3.5 ounces) of apple seeds would be enough to kill a 70-kilogram (154 lbs.) adult. However, an apple seed weighs 0.7 grams (0.02 ounces), so you would have to munch on 143 seeds to get that amount of cyanide. Apples typically have about eight pips, so you'd have to eat the seeds of 18 apples in one sitting to get a fatal dose.
Apple history and facts
Apples originated in the mountainous region of present-day Kazakhstan. The trees grew 60 feet tall and produced fruit in all sizes between a marble and a softball in shades of red, green, yellow, and purple, according to Cornell University. According to the University of Illinois Extension service, apples were consumed at least as far back as 6500 B.C.
Various trade routes passed through these trees, and apples were likely picked by hungry traders, who then discarded the seeds along their paths and probably carried the seeds with them to plant in other destinations. The seeds naturally hybridized with other local species, producing thousands of different types of apple trees across Europe and Asia. The seeds eventually made it to other continents and countries, including North America and New Zealand.
The first apples grown in North America were planted by European settlers in the Massachusetts Bay Colony. Newton Pippin apples were the first type of apple to be exported from the colonies, when they were sent to Benjamin Franklin in London. Today, nearly 25 percent of apples grown in the U.S. are exported around the world.
More fun facts about apples from the University of Illinois Extension service:
- There are 7,500 varieties, or cultivars, of apples grown throughout the world and 2,500 varieties in the U.S.
- The world's top apple producers are China, the United States, Turkey, Poland and Italy.
- Apples are grown in all 50 states.As of 2010, the U.S. Department of Agriculture reported that 60 percent of the apples produced in the U.S. were grown in Washington state, 13 percent in New York, 6 percent in Michigan, 5 percent in Pennsylvania, 3 percent in California and 2 percent in Virginia.
- In 1730, the first apple nursery was opened in Flushing, New York.
- The science of apple growing is called pomology.
- Apples are members of the rose family, Rosaceae
- Check out even more fun facts about apples from the University of Illinois.
- Review more apple crop yield statistics from the USDA National Agricultural Statistics Service.
- Find information on fruit and vegetable safety from the CDC.
This article was updated on Dec. 12, 2018 by Live Science Contributor Rachel Ross.