The review, published in the American Journal of Clinical Nutrition, used data from 12 studies with a combined total of more than 13,000 participants. The studies looked at the relationships between prostate cancer risk and blood selenium levels, selenium content of toenail clippings, and selenium intake.
The reviewers combined the data and analyzed it to identify whether a relationship existed. They looked at:
Although some of the studies did not show this tapering off of protection from selenium, the reviewers speculated that selenium levels and intakes in these studies may not have been high enough to show the possible detrimental effects of having too much.
The results led the reviewers to comment on the complex nature of the relationship between selenium and prostate cancer, saying, “We showed in our dose-response meta-analysis that a decreased risk of prostate cancer appears to be associated with a relatively narrow range of selenium status.” They emphasized the importance of clearly identifying the ideal range in order to make safe recommendations about supplementing with selenium.
Selenium is a mineral micronutrient and a powerful antioxidant. Scientists believe it plays a role in cancer prevention and some studies have found that it protects against colon and lung cancers, as well as prostate cancer. It also keeps the immune system strong and appears to protect the heart and blood vessels.
Here are some ways to ensure that you get enough selenium every day:
(Am J Clin Nutr 2012; doi: 10.3945/ajcn.111.033373)