Do Selenium Supplements Help Prevent Prostate Cancer?

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In case you haven’t seen earlier studies, a new Phase III trial provides evidence concerning whether selenium supplements help prevent prostate cancer, and the answer is no. This latest study was done to determine if selenium benefits might protect men who have high-grade PIN prostatic intraepithelial neoplasia (HGPIN) against developing prostate cancer. Men with HGPIN have an increased risk of prostate cancer.

A total of 423 men with HGPIN participated in the double-blind, randomized, placebo-controlled trial in which half the men took 200 micrograms (mcg) of selenium (as selenomethionine) vitamin daily while the other half took placebo. Over a three-year period, the rates of prostate cancer were 35.6% in the selenium group and 36.6% in the placebo group. Most of the men in both groups who developed prostate cancer also had similar Gleason scores of 6 or less.

Earlier studies have come up with similar results. In the large-scale Selenium and Vitamin E Cancer Prevention Trial (SELECT Trial), investigators found that selenium did not prevent the development of prostate cancer.

In another study that examined the impact of 200 mcg selenium on men with HGPIN, the researchers reported that after three years, selenium had no protective effect against the development of prostate cancer when compared with placebo.

So although selenium is a mineral that is necessary for overall health (55 mcg daily for adults), this study provides more evidence that selenium benefits are not as clear as originally thought and that selenium doesn’t protect against prostate cancer, and in particular for men who have high grade PIN (HGPIN).

Read more in our Prostate Cancer Health Center.


Lippman SM et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: The Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA 2009 Jan; 301(1):39-51.

Marshall JR. Presented at the American Urological Association Annual Meeting, May 29 to June 3, 2010, San Francisco.

Marshall JR et al. Phase III trial of selenium to prevent prostate cancer in men with high-grade prostatic intraepithelial neoplasia: SWOG S9917. Cancer Prev Res (Phila) 2011 Sep 6; DOI: 10.1158/1940-6207