There is no convincing scientific evidence that taking large amounts of vitamin C, vitamin E, or the nutrients selenium and beta carotene can reduce the chances of getting cancer, heart disease, diabetes, Alzheimer's disease or other illnesses, a National Academy of Sciences panel announced Monday.
Despite popular belief that high doses of these so-called antioxidants can protect the body from a variety of illnesses, including the common cold, there is insufficient evidence to recommend that Americans get more of these nutrients than is necessary to prevent basic nutritional deficiencies, the panel said. In fact, extremely high doses might lead to health problems, according to the panel, which for the first time set upper limits for vitamins C and E and for the mineral selenium.
The panel, which is revising all the government's official recommendations for how much vitamins and minerals Americans should get every day, also found insufficient evidence to set a minimum intake level for beta carotene, one of the most popular antioxidant supplements, or for lutein or lycopene. And because of evidence that beta carotene can potentially cause cancer in some people, especially smokers, the panel urged caution before taking it in high doses, recommending supplements "only for the prevention and control of vitamin A deficiency."