Letter by Violi and Pignatelli Regarding Article, “Effects of Random Allocation to Vitamin E Supplementation on the Occurrence of Venous Thromboembolism: Report From the Women’s Health Study” To the Editor:

Vitamin E supplementation has been widely studied in interven-tional trials in patients with cardiovascular disease, but the results have been disappointing.1 These trials were planned on the assump-tion that vitamin E possesses antioxidant properties that may retard atherosclerosis. In the trial by Glynn et al,2 vitamin E supplementa-tion was given to healthy women on the assumption that vitamin E possessed antithrombotic properties that could prevent the occur-rence of venous thromboembolism. During a follow-up of 10 years, the trial demonstrated that vitamin E supplementation (600 IU every other day) reduced the risk of venous thromboembolism, indicating that it may have an antithrombotic effect in vivo; however, the underlying mechanism of this effect was not clarified. The authors report that vitamin E interferes with vitamin K–dependent clotting factor activation2 but fail to mention that, at concentrations achiev-able in the human circulation, vitamin E is also able to inhibi