Selenium is a trace mineral that is essential to good health but required only in small amounts [1,2]. Selenium is incorporated into proteins to make selenoproteins, which are important antioxidant enzymes. The antioxidant properties of selenoproteins help prevent cellular damage from free radicals. Free radicals are natural by-products of oxygen metabolism that may contribute to the development of chronic diseases such as cancer and heart disease [2,3]. Other selenoproteins help regulate thyroid function and play a role in the immune system [4-7].
http://www.ncbi.nlm.nih.gov/pubmed/12134713
