Is it true that apples are the healthiest fruit, as that old keeps the doctor away saying suggests? Diane L. McKay, PhD, an assistant professor at Tufts Friedman School, says, This is actually one of the questions I like to pose to our PhD candidates during their qualifying exam.
The answer, McKay says, is that its impossible to pick any single fruit as the healthiest-but apples certainly belong on the list of those you can benefit from regularly consuming.
Start with apples fiber content. A medium apple, with peel, contains 4.4 grams of dietary fiber-a good amount, but its the makeup of that fiber thats especially healthy. They have both soluble fiber (pectin) on the inside and insoluble fiber (cellulose) in the skin, McKay explains. Soluble fiber can help remove cholesterol from our body (like the soluble fiber in oats, barley and beans), slow down the absorption of glucose, and promote healthy bacteria in the colon. The insoluble fiber helps move things along to maintain a healthy GI tract-i.e., prevent constipation, hemorrhoids and diverticular disease. Note that peeling an apple means throwing away more than half the fiber.
Both types of fiber can help keep you fuller for longer periods of time, which can help keep your calorie intake lower and, thereby, promote weight loss, McKay adds. In fact, one study showed that people who ate an apple 15 minutes before mealtime consumed a net fewer 60 calories, including the calories in the apple. One medium apple delivers a lot of healthy nutrients with only about 100 calories.
POLYPHENOL POWER: McKay goes on, Then there are the phytochemicals in apples, also mostly in the peels. These include a type of antioxidants called polyphenols; among those in apples are quercetin, kaempferol, myricetin, epicatechin and chlorogenic acid (the same polyphenol that gives coffee much of its health benefits). In red apples, the color comes from polyphenols called anthocyanins.
Red apples arent necessarily healthier than green varieties such as Granny Smith, however. One study showed significantly higher amount of total phenolics in Granny Smith apples, while in another study Red Delicious came out on top, McKay says. The green varieties tend to be slightly lower in both calories and carbohydrates, while the red varieties tend to be higher in beta-carotene.
Apple polyphenols can also help with blood sugar, because they inhibit enzymes that break complex carbohydrates down into simple sugars. They have also been shown to lessen absorption of glucose from the digestive tract.
Both the soluble fiber and polyphenols in apples may have cardiovascular benefits, helping to improve cholesterol levels and reduce oxidation of fats in the bloodstream. Quercetin has anti-inflammatory effects, and apple consumption has been linked to lower levels of C-reactive protein (CRP), a marker of inflammation tied to heart disease. Eatingeven less than the apple-a-day level of familiar phrase may still have cardiovascularbenefits: One Finnish study found women who ate more than 71 grams of apples daily (about half a medium apple) were at 43% lower risk of coronary mortality, while men saw a smaller benefit from 54 grams or more daily. Apples high polyphenol content contributes to the fruits rapid browning. When sliced or bruised and exposed to air, the polyphenols start oxidizing. Damaged apples also release ethylene gas, which hastens ripening-so, yes, one bad apple can spoil the whole bunch.
CANCER AND COGNITION: Although eating more fruits and vegetables in general is associated with lower cancer risk, apples are among only a few individual fruits with an anti-cancer connection. For reasons not yet fully understood, apples are particularly linked to lower risk of lung cancer-much as they also seem to have anti-asthma benefits in the lungs. A 2005 Italian study as well as animal tests have further suggested apples may reduce the risk of other cancers, including colorectal, larynx, breast and ovarian.
Apples could also be good for your brain. Tests in mice found a significant improvement in cognitive performance after feeding the equivalent of about 20 ounces of apple juice in humans. In additionto combating oxidative stress, apple compounds help prevent the decline of the neurotransmitter acetylcholine that occurs with aging.