NutraBio Selenium Supplement, 200mcg Selenium is an essential component of glutathione, the body's most potent natural antioxidant. Yeast-free selenium amino acid glycinate is an advanced form of chelated selenium with superior absorption. Selenium functions in a number of antioxidant enzyme systems in the body such as glutathione peroxidase (GPx), thioredoxin reductase (TrxR) and iodothyronine deiodinases (IDD). NutraBio uses Albion Minerals Selenium Glycinate Chelate an advanced, more bioavailable and patented form of the essential mineral selenium. While most selenium supplements aren't easily absorbed and cause gastric upset, Albion selenium is chelated with the amino acid glycine to produce small, organic molecules that pass easily through the digestive tract and are gentler on the digestive system. Selenium is a trace mineral involved in many key functions in the body. It has 90 servings. NutraBio is made in the USA.