alfatokoferolia

Alpha-tocopherol, also known as alfa-tokoferolia, is a form of vitamin E, a fat-soluble nutrient essential for humans. It is one of eight naturally occurring forms of vitamin E, comprising four tocopherols (alpha, beta, gamma, delta) and four tocotrienols. Among these, alpha-tocopherol has the greatest biological activity in humans, and most dietary supplements provide the d- or dl- form of alpha-tocopherol.

Biological role and metabolism: alpha-tocopherol functions primarily as a lipid-soluble antioxidant, protecting cell membranes and lipoproteins from oxidative damage caused by reactive oxygen species. It may also influence immune function and other cellular processes, though evidence for specific disease prevention in healthy populations is mixed. Absorption occurs with dietary fat, and the vitamin is transported in chylomicrons to the liver, where hepatic alpha-tocopherol transfer protein preferentially preserves alpha-tocopherol and directs it into circulating lipoproteins for distribution to tissues.

Sources and intake: good dietary sources include vegetable oils (sunflower, safflower, soybean, olive), nuts and seeds, green leafy vegetables, and fortified cereals. The body stores alpha-tocopherol primarily in adipose tissue and the liver. The recommended intake for adults is about 15 mg per day of alpha-tocopherol activity; the upper intake level from supplements and fortified foods is generally set around 1000 mg per day to avoid adverse effects.

Deficiency and safety: deficiency is rare and typically occurs with fat malabsorption or certain genetic disorders, leading to symptoms such as neuropathy, ataxia, retinopathy, and immune dysfunction. Excessive supplementation can increase bleeding risk in some individuals and interact with medications affecting vitamin K.