Editorial: The Hazards of Vitamin E

November 14, 2004

Millions of Americans take big doses of vitamin E with the unproved assumption that the dietary supplement will improve their health. Now it turns out that large doses may actually be harmful.

That perplexing news was delivered by researchers from Johns Hopkins medical institutions last week, in a scientific talk and medical journal article that combined and reanalyzed the results of 19 studies involving some 136,000 people in North America, Europe and China. The researchers concluded that daily doses of 400 international units and above, the amount typically contained in vitamin E capsules, slightly increased the risk of dying from all causes. Those who took the high doses experienced 39 additional deaths per 10,000 people compared with those who took no supplements.

There are reasons to be cautious in generalizing these findings. Some statisticians find the pooling of results from disparate studies unpersuasive. Most of the patients were elderly people suffering from chronic illnesses, so the relevance to younger and healthier people is uncertain. The dose of vitamin E in a typical multivitamin pill, about 30 units, is far below the apparent danger zone.

Yet the findings should sound a cautionary note for millions of people who swallow big-dose vitamin E capsules as an antidote to ward off heart disease, cancer, Alzheimer's and even the common cold. There is scant evidence to support the presumed benefits, and now there is a signal of potential harm.