Apples provide your body with quercetin, a flavonoid antioxidant that protects cells against wear and tear that can contribute to chronic conditions such as heart disease and cancer. Just don't peel them; most of the quercetin found in apples is in the skin, so it's best to wash the fruits well and eat them whole.

In addition to apples, other good sources of quercetin are onions, raspberries, blueberries, cranberries, cherries, broccoli, and leafy greens. Quercetin is a plant pigment that has antioxidant properties. It may be helpful in preventing the oxidation of bad cholesterol and in inhibiting cancerous changes to cells. Studies suggest that people with the highest intakes of quercetin may have a reduced risk of heart disease and lung cancer.