Antioxidants are substances in foods that help protect cells from the ravaging effects of free radicals, or unstable molecules that attack cells and leave them vulnerable to cancer, heart disease, and many other conditions. Fruits and vegetables are a great source of many different antioxidants, including vitamins C, E, and A; beta-carotene; and lycopene.

How Antioxidants Prevent Cancer

A wealth of research from large-scale, randomized clinical trials indicates that antioxidants may slow or possibly prevent the development of cancer, according to the American Institute for Cancer Research. It states that 30 to 40 percent of cancers are directly linked to diet.

Antioxidants neutralize free radicals. Free radicals are molecules with incomplete electron shells that make them more chemically reactive than those with complete electron shells. Exposure to various environmental factors, including tobacco smoke and radiation, can also lead to free radical formation. The most common form of free radicals is oxygen, which becomes electrically charged or “radicalized” when it robs electrons from other molecules, causing damage to the DNA.

Foods Rich in Antioxidants

Antioxidants are abundant in fruits, vegetables, nuts, grains, some meats, poultry, and fish. The following list describes food sources of common antioxidants.

• Beta-carotene is found in many foods that are orange in color, including sweet potatoes, carrots, cantaloupe, squash, apricots, pumpkin, and mangos. Some green leafy vegetables are also high in beta-carotene, including collard greens, spinach, chard, watercress, kale, and romaine lettuce.

• Lutein, which can help promote healthy eyes, is abundant in green leafy vegetables such as collard greens, spinach, and kale.

• Lycopene is a powerful antioxidant found in tomatoes, watermelon, guava, papaya, apricots, pink grapefruit, and blood oranges. Studies show that 85 percent of Americans get their lycopene from tomatoes and tomato products.

• Selenium is a mineral rather than an antioxidant nutrient, but it is essential for antioxidant enzymes. You can find selenium in cabbage, oranges, garlic, grapes, carrots, chard, and turnips. Brazil nuts also contain large quantities of selenium.

• Vitamin A is found in sweet potatoes, carrots, spinach, chard, beet greens, watercress, mangos, cantaloupe, apricots, broccoli, and romaine lettuce.

• Vitamin C, also called ascorbic acid, is found in abundance in mangos, citrus fruit, asparagus, cantaloupe, watercress, Brussels sprouts, cauliflower, strawberries, and papaya.

• Vitamin E is found in almonds, mangos, nuts, broccoli, asparagus, carrots, tomatoes, spinach, and watercress. It is also found in several oils, including wheat germ, safflower, corn, and soybean oils.