Selenium supplements have been marketed as a natural method of preventing prostate cancer, but the scientific evidence supporting this claim is controversial.

Selenium supplements have been marketed as a natural method of preventing prostate cancer, but the scientific evidence supporting this claim is controversial.

Now, scientists report that, for men who already have prostate cancer, taking selenium supplements may actually be harmful. This finding was published online June 15, 2009 in the Journal of Clinical Oncology.

Researchers from the University of California, San Francisco and their colleagues studied 489 patients with localized or locally advanced prostate cancer in order to evaluate the association between selenium levels in the blood, prostate cancer, and a certain variant of a gene called manganese superoxide dismutase (SOD2). The scientists found that, among prostate cancer patients with the SOD2 gene variant, higher levels of selenium in the blood might increase the likelihood of having more aggressive disease.

It is important to note that, in this study, there was no way of which patients had been taking selenium supplements. This study only examined the levels of selenium in the blood, regardless of source. Further studies are needed to determine which men can safely take selenium supplements. Until these data are available, it might be wise for patients with prostate cancer to avoid taking selenium-containing supplements.

Source:

JCO Early Release, published online ahead of print June 15, 2009.