Are Vitamin E Supplements a Risk for Prostate Cancer?

When I was a medical student, many years ago, vitamin E was being touted as a cure for male infertility – based solely on its effectiveness in this condition in rats.  Unfortunately, it was not effective in men.  Since then nutritionists have sought other possible uses for this fat-soluble vitamin with antioxidant properties.  Starting in 2001, 35,500 North American men were enrolled in a study of oral selenium and vitamin E as possible agents for preventing cancer.  At a first analysis, those men in the groups taking vitamin E alone and vitamin E plus selenium showed a non-significant trend toward an increased risk of prostate cancer.  The trial was stopped, because it was clear that the supplements didn’t protect against cancer.  Now the results of analysis of all the data available up to July 2011 have been published in the Journal of the American Medical Association. 

After an average of roughly 7 years' follow-up, men given vitamin E alone showed a 17% relative increase in prostate cancer risk over those on placebo.  This increase, although significant, was in fact small - 10.9 vs. 9.3 cancers per 1000 person-years. The men given selenium alone and selenium plus vitamin E had non-significant increased prostate cancers compared with the placebo group: 9% and 5%, respectively.  

The authors found no apparent explanation for the increased risk with vitamin E, and other experts have tended to dismiss the possible danger, in spite of considerable media attention. One thing is clear – neither vitamin E nor selenium showed any reduction in the risk of cancer in men, and there is little reason for people to take high-dose supplements of either.