Vitamin E supplements don’t protect healthy women against heart attacks and stroke, according to the latest results from the Women’s Health Study, a long-term clinical trial funded by the National Heart, Lung, and Blood Institute (NHLBI) and National Cancer Institute (both part of NIH). The vitamin also had no effect on the most common cancers in women or on total cancers.

An estimated 13.5% of women in the U.S. take vitamin E supplements. Laboratory and animal research has suggested that vitamin E might reduce the chance of clogged and blocked arteries. Observational studies suggested that people who eat foods high in vitamin E or take supplements have a lower risk of heart disease. Although several clinical trials have found little cardiovascular benefit from vitamin E, these trials were not conclusive. The Women’s Health Study aimed to look at the long-term effects of vitamin E among a large number of healthy women, studying 39,876 women age 45 years and older over an average of 10.1 years.

The study found that vitamin E didn’t significantly affect major cardiovascular “events”—a combination of nonfatal heart attack, nonfatal stroke and cardiovascular death. There were findings that warrant further study, however. There was some reduction in cardiovascular deaths among women taking the vitamin. Women 65 and older taking vitamin E also had a decrease in heart attacks and cardiovascular deaths (but not strokes). Total deaths, however, were unaffected by vitamin E.

NHLBI director Dr. Elizabeth G. Nabel says women shouldn’t rely on vitamin E supplements to prevent heart attack and stroke. “Instead,” she said, “women should focus on well-proven means of heart disease prevention, including leading a healthy lifestyle and controlling risk factors such as high blood pressure and high cholesterol.”