Antioxidants are substances that may protect your cells against the effects of free radicals. Free radicals are molecules produced when your body breaks down food, or by environmental exposures like tobacco smoke and radiation. Free radicals can damage cells, and may play a role in heart disease, cancer and other diseases. Antioxidant substances include Beta-carotene Lutein Lycopene Selenium Vitamin A Vitamin C Vitamin E Antioxidants are found in many foods. These include fruits and vegetables, nuts, grains, and some meats, poultry and fish.