Study Doubts Benefits of Vitamin E for Women

Vitamin E supplements, taken by millions of Americans as a potential cure-all, do not prevent heart disease and stroke in most women, but may provide some protection among those over age 65, according to a major new study involving nearly 40,000 women.

Vitamin E capsules are widely recommended by cardiologists for heart disease prevention because such antioxidants are thought to prevent the buildup of plaque in arteries.

The authors of the study, which appears today in the Journal of the American Medical Assn., and its major sponsor, the National Institutes of Health, think such recommendations are misguided.

“We can now say that, despite their initial promise, vitamin E supplements do not prevent heart disease and stroke,” said Dr. Elizabeth G. Nabel, director of the NIH’s National Heart, Lung and Blood Institute.

Vitamin E proponents had a different response to the study, arguing that the results among older women showed a powerful benefit.

“This research is actually one of the most exciting studies in a decade to show the profound benefits of vitamin E in older women, around the ages where they generally begin to get heart disease,” said Dr. Maret G. Traber, an Oregon State University expert on vitamin E.

“The data from this study showed that in a group of about 4,000 women over age 65, supplementation with vitamin E caused a 24% decrease in major cardiovascular events, a 34% reduction in heart attacks and a 49% reduction in cardiovascular death,” she said.

Researchers at Brigham and Women’s Hospital in Boston said the findings arose from a small subgroup of the study population and deserved further review, but they still did not recommend vitamin E supplements.

“I find that conclusion inexplicable,” Traber said.

The study involved 39,876 female healthcare professionals over 45 who were studied for at least 10 years.

The women were divided into four groups that, every other day, received one of the following: aspirin and a placebo; 600 international units of vitamin E and a placebo; aspirin and vitamin E; or two placebos.

Overall, 184 women in the vitamin E group and 181 in the placebo group had nonfatal heart attacks; 220 in the vitamin E group and 222 in the placebo group had nonfatal strokes.

Adding in heart attack deaths, there were 482 cases of heart attack and stroke in the vitamin E group and 517 in the placebo group -- a 7% difference that was not statistically significant.

“A healthy lifestyle and regular screening ... are a woman’s best choice for disease prevention,” said lead author I-Min Lee of Brigham and Women’s Hospital.

Earlier results from the study, reported in March, demonstrated that low doses of aspirin did not protect women against heart disease and stroke, even though they did have a protective effect in men.

The new results “highlight the importance of recognizing biological differences between the sexes in cardiovascular research by providing valuable sex-specific data on primary prevention,” wrote Dr. Rita F. Redberg of UC San Francisco in an editorial in the same issue of the journal.

Results from a similar study of vitamin E in men are not expected until 2008, she said.

One reason for the unexpected findings in the women’s study may lie in the nature of heart disease. Although heart disease is the No. 1 cause of death in both sexes, women tend to develop symptoms about 10 years later than men, on average.

Many researchers attribute the difference to the protective effects of naturally occurring estrogen in women, although supplemental estrogen after menopause does not appear to extend the protection.

According to Traber, 3.6% of women between 55 and 64 have heart disease, a much lower proportion than among men. The potential protective effect of vitamin E may be apparent only in women over 65.

The Women’s Health Study also found that neither vitamin E nor aspirin protected against cancer in general or against the types of cancer most common among women -- lung, breast and colon.

The study identified 2,865 cases of cancer overall, with no significant differences between the vitamin E and placebo groups and between the aspirin and placebo groups.

They observed a slight “tending” toward protection against lung cancer by aspirin and recommended further study.

Study author Nancy R. Cook of Brigham and Women’s Hospital recommended against prescribing low doses of aspirin as a primary method to prevent cancer.