Apples contain a type of soluble fiber called pectin that has been shown to help lower LDL, or bad, cholesterol levels. They are also high in antioxidants, which may help to reduce the risk of cancer and cardiovascular disease, and they are low in calories, so they are unlikely to contribute to weight gain when eaten in moderation. Apples also contain polyphenols, which may contribute to healthy blood-sugar regulation.
Since the average apple contains just 126 calories, apples are commonly touted as a weight-loss food. Most of these calories come from carbohydrates; the average apple contains 13.81 grams of carbohydrates. Eating an apple with a meal may increase the feeling of fullness without increasing calorie intake, since the average apple contains 4.37 grams of dietary fiber, a nutrient that contributes to feelings of fullness. Many of the health benefits of apples are derived from their high content of phytochemicals, such as quercetin and epicatechin. These and other nutrients are primarily found in the apples' skin.
The health benefits of apples have long been touted. The saying "An apple a day keeps the doctor away" arose in the 19th century, and recent research confirming the anti-cancer and cholesterol-lowering effects of apples suggests that there is some truth to this proverb.