Supports a healthy immune system and is antagonistic to heavy metals. Hypoallergenic. Gluten and casein free. Capsules are plant based. Ultra Tested. Selenium is an essential trace mineral that functions primarily to provide antioxidant activity in the body. It works synergistically with vitamin E in reducing free radical damage to cell membranes. Selenium is also associated with supporting a healthy immune system.Selenium is antagonistic to heavy metals including lead, mercury, aluminum and cadmium and may offer protection from environmental traces of these contaminants.Kirkman's selenium capsules utilize LSelenomethionine as the selenium source. This is a biologically active form, which was very effectively absorbed in clinical studies conducted by the Nutrition 21 Corporation.