Vitamin E supplement may increase prostate cancer risk, national U.S. study finds

The finding comes from a report summarizing the latest results of the Selenium and Vitamin E Cancer Prevention Trial (SELECT). Eric Klein, M.D., chair of the Glickman Urological and Kidney Institute at Cleveland Clinic, is the lead author.

SELECT began in 2001 to test earlier research suggesting selenium and vitamin E supplements may reduce the risk of developing certain cancers. Some vitamin supplements containing enhanced levels of selenium and vitamin E were marketed to consumers during this time period with claims of reducing cancer risk.

The paper, which will appear in the October 12 edition of the Journal of the American Medical Association, found that a group of men taking a daily dose of 400 IU of vitamin E from 2001 to 2008 had 17 percent more cases of prostate cancer than men who took a placebo.

"For the typical man, there appears to be no benefit in taking vitamin E, and in fact, there may be some harm," said Dr. Klein, an internationally renowned prostate cancer expert who served as the national study coordinator.

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 trial was funded by the National Cancer Institute and administered by the Southwest Oncology Group (SWOG), an international network of research institutions with study sites in 400 locations across the U.S., Puerto Rico and Canada.

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.

Prostate cancer is the most common non-skin cancer in American men with a current lifetime risk of 16 percent. For 2011 it is estimated 240,000 new cases and 33,000 deaths will result in the U.S.

Men who participated in the SELECT trail can find more information at www.SWOG.org.