Selenium, a trace essential mineral, is a component of many antioxidant enzymes, which inhibits oxidation by Reactive Oxidative Species (ROS). Selenium acts as an antioxidant in the metabolism of the thyroid, oxidation/reduction reaction, reproduction and immune function.

Generally, Selenium deficiency depresses the immune function, and Selenium reacts with heavy metals, such as cadmium, silver, and mercury in the foods, for protecting our body from these toxins.