Some men who take high doses of selenium and vitamin E supplements could increase their risk of aggressive prostate cancer, according to a recent study led by Dr. Alan Kristal, professor of epidemiology at the University of Washington School of Public Health and a member of the Fred Hutchinson Cancer Research Center.

In a study published in the Journal of the National Cancer Institute, Dr. Kristal and colleagues found that taking selenium supplements increased the risk of high-grade prostate cancer by 91 percent among older men with higher levels of selenium (as measured in toenails). The supplements also offered no benefit for men with low levels of selenium. Researchers also found that taking vitamin E supplements increased the overall risk of prostate cancer by 63 percent among men with low levels of selenium.

Selenium is a trace mineral that some people take for its antioxidant properties. Data and samples were analyzed from the Selenium and Vitamin E Cancer Prevention Trial, a larger study of more than 35,000 men. "Men using these supplements should stop, period," said Dr. Kristal. "Neither selenium nor vitamin E supplementation confers any known benefits – only risks."

Last year, Dr. Kristal was senior author of a study confirming the links between fish-oil supplements and high levels of omega-3 fatty acids to an increased risk for prostate cancer.

Link: http://jnci.oxfordjournals.org/content/early/2014/02/21/jnci.djt456.abstract