Vitamin E is a fat-soluble vitamin. There are eight forms of vitamin E, however, the most biologically active form is d-alpha-tocopherol. The best defined role for vitamin E is an antioxidant for unsaturated fatty acids in cell membranes. It is also important in energy metabolism and synthesis of RNA, DNA, and red blood cells. It acts as an antioxidant in the lungs against smog. Vitamin E is absorbed in the presence of bile in the small intestine. Deficiency of vitamin E may result in hemolysis of RBC's, sterility, higher risk for heart disease and stroke.