Antioxidants: What You Need to Know

How Much Do I Need?

The American Heart Association, for one, does not recommend using antioxidant supplements "until more complete data are in," but instead, suggests "people eat a variety of foods daily from all of the basic food groups." Moreover, in April 2000, the Food and Nutrition Board of the Institute of Medicine, an advisory group that is part of the National Academy of Sciences, reported that Vitamin C, vitamin E, selenium, and carotenoids like beta-carotene should come from food, not supplements. After examining available data on the beneficial and harmful health effects of antioxidants, the panel concluded that there isn't enough evidence to support using large doses of these nutrients to combat chronic diseases. In fact, the group warned that extremely high doses of antioxidants may lead to health problems, including diarrhea, bleeding, and the risk of toxic reactions.

Since 1941, the Food and Nutrition Board has determined the types and quantities of nutrients that are needed for healthy diets by reviewing scientific literature, considering how nutrients protect against disease, and interpreting data on consumption of nutrients. For each type of nutrient, the Board has established a Recommended Dietary Allowance (RDA)-a daily intake goal for nearly all (98 percent) healthy individuals, and a "tolerable upper intake level" (UL)-the maximum amount of a nutrient that healthy individuals can take each day without risking adverse health effects. In some cases, the Board has decided there isn't enough evidence to determine the amount at which a particular nutrient is essential or harmful to health.

Over the last several years, the Board has been updating and expanding the system for determining the RDA and UL values, which are now collectively referred to as the Dietary Reference Intakes, or DRIs. The following recommendations were made for consumption of antioxidants in the 2000 report, "Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids":

RDA (adults)
Upper Level (adults)
Vitamin E
15 mg
1,070 mg natural vitamin E

785 mg synthetic vitamin E

Higher amounts impair blood clotting, increasing likelihood of hemorrhage.
Vitamin C
Women: 75 mg
Men: 90 mg
2,000 mg
Higher amounts could lead to diarrhea and other GI disturbances. Extremely high levels may lead to cancer, atherosclerosis, and kidney stones.
Chronic high doses turn your skin yellow-orange, but it is not toxic. However, research indicates it is unwise to consume doses of beta-carotene beyond what is in a multivitamin and your regular diet.
55 micrograms
400 micrograms
Higher amounts could cause hair loss, skin rashes, fatigue, GI disturbances, and nervous system abnormalities.