Studies have found that eating apples on a regular basis significantly cuts the risk of heart disease, most likely because they contain a lot of antioxidants.
A medium unpeeled apple contains 4 grams of fiber, about one-fifth the amount most women should consume in a day (and more than the amount in a serving of many whole-wheat breads). Some of that fiber is soluble and can help lower LDL ("bad") cholesterol. The rest is insoluble, which aids digestion and weight control.
Several studies have connected the consumption of apples with a reduced risk of cancer, particularly lung cancer. Research also suggests that people who regularly eat apples are less susceptible to asthma. The fruit may protect the body against the risk of 2 diabetes as well.
Everyday Food, Martha Stewart September 2009