Clinical Evidence for Vitamin E continued...
After 7.5 years, researchers found no differences between the antioxidant group and the placebo group in terms of heart disease, cancer incidence, or death from all causes. However, when the researchers looked at cancer incidence according to gender, supplementation did appear to protect men but not women from developing cancer. Men were 31% less likely to develop cancer than women.
On average, the men had lower levels of antioxidants in their blood at study entry than did the women, and the researchers conclude that this could explain the difference in protection.
"The ineffectiveness of supplementation in women may be due to their better baseline antioxidant status," they wrote.
Time to Abandon Antioxidants?
So what do the new studies mean for people still taking mega doses of antioxidants? Johns Hopkins University epidemiology professor Eliseo Juallar, MD, says it is now clear that the practice is of little or no benefit for preventing disease and could be harmful.
Juallar coauthored the widely publicized review presented at an American Heart Association (AHA) meeting earlier this month, finding that high-dose vitamin E supplementation is associated with an increased risk of dying.
The study's relevance for young, healthy people has been questioned, because the researchers focused on trials involving mostly elderly, chronically ill patients. But the Johns Hopkins researcher says the evidence is clear.
"There is no question that beta-carotene at high doses is harmful, and it is also clear that [high-dose] vitamin E is not protective and might be harmful," he says.
Juallar contends that taking as little as 400 IU of vitamin E -- the most widely sold dosage -- may be dangerous. AHA nutrition spokeswoman Alice Lichtenstein, DSc, says it is now obvious that vitamin E supplementation does not protect against heart disease, but the evidence that it is harmful is not completely convincing.
"What we can say is that there do not appear to strong enough data to advise people to take antioxidant vitamins, including vitamin E, to reduce their risk of cardiovascular disease," she tells WebMD.
SOURCES: Hercberg, S. Institut National de la Sante et de la Recherche Medicale (INSERM) and Unite de Surveillance et d'Epidemiologie Nutritionnelle, Paris. Eliseo Juallar, MD, DRPH, assistant professor of epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Md. Alice Lichtenstein, D.Sc, senior scientist and director, Cardiovascular Nutrition Laboratory, Tufts University Friedman School of Nutrition. Boston; chair, nutrition committee, American Heart Association. Eidelman et al., Archives of Internal Medicine, July 26, 2004; vol 164: pp 1552-1556. AHA Scientific Sessions 2004, New Orleans, Nov. 7-10, 2004.