Vitamin E may increase prostate Ca risk, analysis of SELECT data shows

Men who take a daily vitamin E supplement face an increased risk of prostate cancer, according to a new report summarizing the latest results of the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

The results, which were published in JAMA (2011; 306:1549-56), found that a group of men taking a daily dose of 400 IU of vitamin E from 2001 to 2008 had 17% more cases of prostate cancer than men who took placebo.

"For the typical man, there appears to be no benefit in taking vitamin E, and in fact, there may be some harm," said first author Eric Klein, MD, of the Glickman Urological and Kidney Institute at Cleveland Clinic.

SELECT tracked more than 35,000 men at locations across the United States, Canada, and Puerto Rico who took daily doses through the fall of 2008. The men were divided into four groups: vitamin E and selenium; vitamin E alone; selenium alone; and placebo. The group taking vitamin E was the only group shown to have a statistically significant increased risk of prostate cancer.

Earlier, considerable preclinical and epidemiologic evidence indicated that selenium and vitamin E may reduce prostate cancer risk. The initial report of SELECT, published in December 2008, "found no reduction in risk of prostate cancer with either selenium or vitamin E supplements but a statistically nonsignificant increase in prostate cancer risk with vitamin E," Dr. Klein and colleagues wrote. "Longer follow-up and more prostate cancer events provide further insight into the relationship of vitamin E and prostate cancer.

"In this article, we report an observation of important public health concern that has emerged with continued follow-up of SELECT participants. Given that more than 50% of individuals 60 years or older are taking supplements containing vitamin E and that 23% of them are taking at least 400 IU/d despite a recommended daily dietary allowance of only 22.4 IU for adult men, the implications of our observations are substantial."

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