title: Vitamin E: a reexamination.
abstract: An attempt is made to place into proper perspective the relative values of the eight natural forms of vitamin E and the epimers of the synthetic products with regard to their biological activities. Since differences in activities reported are mostly in a function of different rates of biological turnover, feeding a non-alpha-tocopherol compound three times a day would be expected to give a different biological value than if the total were fed once a week or together with alpha-tocopherol. An analysis of data to support an increase in the current RDA for vitamin E is presented. Recent developments on the prolongation of blood clotting time by vitamin E are interpreted from the viewpoint that alpha-tocopherol is oxidized to tocopherylquinone, which is an inhibitor of vitamin K.
mesh_terms: D000397:Air Pollution; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001777:Blood Coagulation / Q000187:drug effects; D055598:Chemical Phenomena; D002621:Chemistry; D002648:Child; D004355:Drug Stability; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005260:Female; D006801:Humans; D007223:Infant; D007536:Isomerism; D008168:Lung / Q000187:drug effects; D008297:Male; D009132:Muscles / Q000502:physiology; D009751:Nutritional Requirements; D010084:Oxidation-Reduction; D011247:Pregnancy; D012098:Reproduction; D013329:Structure-Activity Relationship; D014481:United States; D014810:Vitamin E / Q000494:pharmacology / Q000502:physiology; D014811:Vitamin E Deficiency / Q000201:enzymology; D014812:Vitamin K / Q000037:antagonists & inhibitors
chemical_list: D000975:Antioxidants; D005231:Fatty Acids, Unsaturated; D014812:Vitamin K; D014810:Vitamin E