Data from the 1970s first suggested that
vitamin E may be effective in decreasing mortality from
cardiovascular disease. As the understanding of the
antioxidant effect of this
vitamin evolved, researchers began to further study the
biologic effects of
vitamin E. In vitro studies have shown
vitamin E to have several potentially cardioprotective effects, including antagonizing the oxidation of
low-density lipoproteins, inhibiting platelet aggregation and adhesion, preventing smooth muscle proliferation, and preserving normal coronary dilation. Several prospective studies, including the US Nurses' Health Study and the US Health Professionals' Follow-up Study, found a 34% and 39% reduction, respectively, in the risk of having a
cardiac event for those taking
vitamin E supplements. The Iowa Women's Health Study found a 47% reduction in cardiac mortality. Results of randomized, controlled clinical trials have not found consistent benefit, however. The best known of these trials, the Cambridge Heart
Antioxidant Study, found a 47% reduction in fatal and nonfatal
myocardial infarction in patients with proven
coronary atherosclerosis who were given 400 or 800 IU of
vitamin E daily. There was, however, no effect on mortality. While emerging and promising data suggest the potential benefit of
vitamin E for high-risk cardiac patients, physicians should be alert to the results of randomized, controlled clinical trials already in progress.