Vitamins E and C confirmed safe at high doses

May 2 2005

Fourteen leading safety and antioxidant experts reviewed the available scientific literature on vitamins E and C and concluded vitamin E is safe for the general population at intakes up to 1600 IU daily and vitamin C is safe at up to 2000 mg daily, according to a new article published in the April issue of the American Journal of Clinical Nutrition (AJCN).

"This peer-reviewed expert analysis should help reassure consumers about the safety of vitamin E for a healthy population at the most common daily doses on the market -- 400 IU and 200 IU -- for vitamin E single supplements," said John Hathcock, Ph.D., vice president, scientific and international affairs, Council for Responsible Nutrition (CRN), and the lead author on the article. However, Dr. Hathcock pointed out that consumers should not view the study's conclusions as a license to exceed recommended doses on product labels, noting that the UL ("Tolerable Upper Intake Level") is a dose at which "there is no known harm but it is not a recommendation or suggestion for daily use."

In reviewing the available scientific literature on vitamins E and C, the scientists reviewed clinical trials as well as epidemiological studies in humans, determining there was sufficient information from human data to support a conclusion on safety. This is in contrast to the approach taken by the Institute of Medicine (IOM), a scientific advisory body, which established its UL for vitamin E based on an extrapolation from animal data. The IOM set a UL at 1000 mg for vitamin E (which is equivalent to 1000 IU synthetic; 1500 IU natural).

With regard to vitamin C, the authors noted that "Numerous studies of vitamin C supplementation have provided no pattern of evidence to support concerns about safety other than occasional gastrointestinal upset or mild diarrhea..." The authors came to the same conclusion as the IOM in establishing the UL at 2000 mg for vitamin C.

The review of the scientific literature encompassed 95 references, including the recent, controversial meta-analysis on vitamin E from Johns Hopkins University.

Vitamins E and C are among the most popular dietary supplements. Many studies suggest that these antioxidant supplements, either alone or in combination with other supplements, can help promote overall good health and be helpful in lowering the risk of specific chronic diseases, such as Alzheimer's, age-related macular degeneration, cataracts, some types of cancer, and ischemic heart disease.