Vitamin E is the primary lipid-soluble antioxidant in human biology, required for free radical protection of structures having high lipid content such as cell and organelle membranes, lipoprotein particles, and the central nervous system environment. Clinical research has discovered specific functions of vitamin E for supporting immunocompetence, optimal circulation and joint health. E-400 is a natural extract and supplies not only the primary alpha-tocopherol vitamer, but also the beta-, delta-, and gamma-vitamers, in order to more closely match the variety of forms found in the diet. E-400 is also unesterified, making it suitable for external use as well.