Selenium is advertised as yeast sourced Selenium, a trace mineral with numerous functions in the body. Selenium is important in the synthesis of several antioxidants, including Glutathione. The formula manufactured by Healthy Origins has received numerous positive reviews from consumers, so we may conclude the formula is fairly effective. Caution is advised when using Selenium, since it can be toxic if used in large amounts. It is advised you first talk to a healthcare provider.