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What is an antioxidant and who should take one?

Antioxidants are vitamins and minerals that help prevent oxygen from reacting with other chemicals in cells. Such reactions may damage cells in ways that make heart disease and cancer more likely. Examples of antioxidants are vitamin A, >vitamin C, >vitamin E, and >beta-carotene.

Vitamin E is the antioxidant that has been studied the most. Some medical research has shown that vitamin E can reduce the risk of heart attacks in people with heart disease. But other studies have not found this same benefit. Also, it has not been proven that vitamin E can prevent people from getting heart disease or cancer.

There’s very little reliable information that shows a benefit from antioxidants other than vitamin E. Studies of vitamin A, vitamin C, and beta-carotene have not shown them to prevent cancer or heart disease.

If you have heart disease, your doctor may suggest that you take vitamin E. A safe and useful dose for improving antioxidant activity is 400 IU per day. Some people believe that natural forms of vitamin E may be more active than synthetic forms, but this has not been proven.

Sources:
American Heart Association Science Advisory Committee. "Antioxidant Consumption and Risk of Coronary Heart Disease: Emphasis on Vitamin C, Vitamin E, and Beta-carotene," Circulation 99 (1999).
Silverman, H., J. Romano, G. Elmer. The Vitamin Book. Bantam Books, 1985.
Christen WG. “Design of Physicians' Health Study II--A Randomized Trial of Beta-Carotene, Vitamins E and C, and Multivitamins, in Prevention of Cancer, Cardiovascular Disease, and Eye Disease, and Review of Results of Completed Trials”, Annals of Epidemiology 10 (2000).
Lee IM. “Beta-carotene Supplementation and Incidence of Cancer and Cardiovascular Disease: the Women's Health Study”, Journal of the National Cancer Institute 15 (1999).
Yusuf S. “Vitamin E Supplementation and Cardiovascular Events in High-Risk Patients. The Heart Outcomes Prevention Evaluation Study Investigators”, New England Journal of Medicine 342 (2000).

This answer prepared 6/2/00.