Selenium is an essential trace mineral in the human body. This nutrient is a component of glutathione peroxidase, an important enzyme that protects arteries and cell membranes from damage by free radicals that are produced during normal oxygen metabolism. The body has developed defenses, such as antioxidants, to control levels of free radicals because they can damage cells and contribute to the development of chronic problems.

Selenium is also essential for normal functioning of the Defense mechanism of body and thyroid gland. Selenium may also aid in protein synthesis, growth and development, and fertility, especially in the male. It has been shown to improve sperm production and motility.