The preferential distribution of alpha-tocopherol in humans over the other forms of tocopherol stems from the faster metabolism of the other forms and from the alpha-tocopherol transfer protein (alpha-TTP). 3 Beta- and delta-tocopherols are found in the plasma in minute concentrations only. Among the tocopherols, the alpha- and gamma-tocopherols are found in the serum and the red blood cells, with alpha-tocopherol present in the highest concentration. The richest dietary sources of vitamin E are edible vegetable oils as they contain all the different homologues in varying proportions. Alpha-and gamma-tocopherols are the two major forms of the vitamin, with the relative proportions of these depending on the source. There are eight naturally occurring forms of vitamin E namely, the alpha, beta, gamma and delta classes of tocopherol and tocotrienol, which are synthesised by plants from homogentisic acid. chroman-6-ols), collectively termed tocochromanols (divided into tocopherols and tocotrienols), includes all of the tocol and tocotrienol derivatives which qualitatively exhibit the biological activity of d-alpha-tocopherol. 1 Vitamin E is present in fat-containing foods 2 and, as the fat-soluble property of the vitamin allows it to be stored within the fatty tissues of animals and humans, it does not have to be consumed every day. V itamin E is the collective term given to a group of fat-soluble compounds first discovered in 1922 by Evans and Bishop these compounds have distinct antioxidant activities essential for health.
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