Vitamin E

( Originally Published 1956 )

Vitamin E has not been shown unequivocally to be essential in human nutrition although evidence suggests that this is the case. In experimental animals, manifestations of vitamin E deficiency include fetal resorption and dystrophic changes in skeletal muscle. In certain clinical diseases in man which resemble experimental deficiency, namely, habitual abortion and progressive muscular dystrophy, therapy with vitamin E has been attempted. Beneficial effects have not been demonstrated in these conditions or in a number of other pathologic states in which vitamin E has been prescribed.

An attempt to produce experimental vitamin E deficiency in adult men is under way at present (154). The only abnormal findings after more than three years on a diet very low in vitamin E are a decrease in the concentration of tocopherols in blood and excessive hemolysis of erythrocytes when tested with hydrogen peroxide in vitro. It seems unlikely that primary deficiency of vita-min E will occur in healthy adults. However, deficiency might arise as a result of impaired absorption, increased requirement or some abnormality in the metabolism of the vitamin.

Plasma tocopherol levels have been found to be much lower in infants than in adults. Normal levels in the former range from 0.23 to 0.43 mg per 100 ml, in the latter from 1.0 to 1.2 mg per 100 ml (155). Gyorgy and associates (156) observed that erythrocytes of newborn infants were more sensitive to hemolysis by hydrogen per-oxide than those of adults and that this sensitivity could be corrected by tocopherol administration. Similar sensitivity to hemolysis has been found in premature infants . It seems likely that supplementation of the diet of premature infants with tocopherol may be desirable since fat absorption is defective and both whole cow's milk and stored human milk have limited tocopherol content.

Evaluation of vitamin E nutrition must rest, at present, upon determination of plasma tocopherol concentration and the use of the in vitro erythrocyte hemolysis test. Absorption of vitamin E may be determined by a tolerance test similar to that described for vitamin A. Subjects are given a large dose of tocopherol (5-20 mg. per kg. body weight) and blood samples taken at 0, 3, 6, 9, 12 and 24 hours. Low curves have been reported in sprue, fibrocystic disease of the pancreas, the celiac syndrome and in some but not all cases of liver disease (155). Analysis of tissues specimens, obtained at biopsy, for tocopherol content may prove to be informative.