Selenium is an essential trace element necessary for the formation of the antioxidant enzyme Glutathione perioxidase (Glutathione Peroxidase), an important enzyme with antioxidant properties that stops the oxidation of fats, especially bad cholesterol (LDL). Selenium is also linked to the sulfur amino acid, methionine, in a natural form, as found in nutrition. Selenium is incorporated into the body in a large number of vital proteins, called selenoproteins. Selenium proteins may reduce the risk of prostate cancer because they are involved in the production of testosterone, a hormone that is an important regulator of both normal and abnormal growth. These proteins also help to regulate thyroid function and play an important role in the immune system.