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Study Shows Vitamin E Increases Prostate Cancer Risk

Article date: October 12, 2011

By Stacy Simon

A follow-up study from a clinical trial that included 35,000 men shows that those who took vitamin E supplements were more likely to develop prostate cancer.


The original study, the Selenium and Vitamin E Cancer Prevention Trial (SELECT), began in 2001 and was designed to find out whether vitamin E and selenium could prevent prostate cancer. More than 35,000 men over age 50 in the US, Puerto Rico, and Canada were enrolled. Each participant was randomly assigned to take either selenium, vitamin E, a combination of the two, or a placebo for the course of the study.

The National Cancer Institute stopped the trial in 2008 because early analysis suggested the supplements didn't work, and could actually be harmful. After an average of 5 years, the analysis found no lower risk of prostate cancer in men taking the supplements, either alone or together. Men who were taking only vitamin E had a slightly higher risk of developing prostate cancer. The increased risk seen was not statistically significant; it could have been due to chance and so didn’t prove the supplements raised prostate cancer risk. Men in the study received letters telling them to stop taking their study pills and researchers continued monitoring the participants.

This follow-up study did find a statistically significant increase. Men who took 400 IU of vitamin E every day during the study were 17% more likely than men who didn’t take the supplement to develop prostate cancer during the 7 years they were monitored by researchers.

The follow-up results are published in The Journal of the American Medical Association.

According to the researchers, more than 50% of people 60 years old or older are taking supplements containing vitamin E, and 23% are taking at least 400 IU a day. They say this emphasizes the importance of large-scale trials to test the benefits and harms of dietary supplements.

Learn more about herbs, vitamins and minerals and what researchers have found out about their use when associated with cancer treatments.

Reviewed by: Members of the ACS Medical Content Staff

ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases.

Citation: Vitamin E and the Risk of Prostate Cancer, The Selenium and Vitamin E Cancer Prevention Trial (SELECT). Published in the Oct. 12, 2011 issue of JAMA (Vol. 306, No. 14). First author: Eric A. Klein, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, Ohio.

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