Vitamin E refers primarily to α-tocopherol, a fat-soluble antioxidant essential for protecting cell membranes from lipid peroxidation caused by reactive oxygen species. It supports immune function, gene expression, and neurological health. Naturally occurring in vegetable oils, nuts, seeds, and leafy greens, it exists in eight forms (tocopherols and tocotrienols), with α-tocopherol exhibiting the highest biological activity in humans. Used in dietary supplements, food fortification, and cosmetics for its stabilizing properties. Deficiency leads to ataxia and hemolytic anemia; excess is excreted due to poor absorption.