Selenium is as essential trace mineral and functions as part of the antioxidant enzyme glutathione peroxidase. It is bonded to the essential sulfur amino acid, methionine, in a naturally occurring form as found in the diet. Selenium is found most abundantly in Brazil Nuts, organ meats, seafood, and wheat germ. From the FDA's website: "Selenium may reduce the risk of certain cancers. Some scientific evidence suggests that consumption of selenium may reduce the risk of certain forms of cancer. However, FDA has determined that this evidence is limited and not conclusive."