746 XI. VITAMINS E (tocopherols j 



League of Nations is defined as the specific actiiaty of 1 mg. of synthetic 

 racemic tocopherol acetate. The international standard contains one mg. 

 of a standard a-tocopheryl acetate in 100 mg. of olive oil. This is the 

 amomit which, when administered orally, prevents resorption-gestation 

 in rats depri^^ed of vitamin E.*6'',460a ^^ ^j^g other hand, the M.F.D. 

 (mean fertility dose), which is more widely emplo.yed, amounts to 0.75 mg. 

 of cK-tocopherol. For a further discussion of vitamin E standards, the 

 reader is referred to The Lipids, Vol. I, pp. 819 and 820. 



It is impossible to make categorical statements about the A'itamin E 

 requirements without setting up precisely the conditions of the diet, age, 

 sex, type of fat, etc. For example, a number of investigators, including 

 Gottlieb et ai.,^" Emerson and Evans, "^^ Dam et al.,*^'^ and Bruce''^^ have 

 observed that the vitamin E requirement is increased by high-fat diets, 

 particularly when they are composed of highly unsaturated fats.^^^ Al- 

 though the daily requirement of the two sexes is about the same in mature 

 rats, Mason'"^ states that the male requirement to pre^'ent irreversible 

 disturbances of the germinal epithelium begins at the age of forty to fifty 

 days, while that of the females to ensure reproduction does not become 

 critical until after conception and implantation, which may occur at any 

 stage of the reproductive period. 



Goettsch and Pappenheimer^^^ reported that the amounts of vitamin E 

 necessary to prevent sterility and to inhibit dystrophy are within the same 

 range in the rat (2.5 mg. vs. 0.5 mg.). However, the amount of vitamin E 

 necessary to protect against "late lactation" paralysis in young rats from 

 vitamin E-deficient mothers depends upon the time of initiation of the 

 vitamin E therapy. Thus, when it is delayed, in the case of suckling rats 

 from the tenth to the seventeenth day, an increased dosage is required for 

 their protection. Evans and Emerson -^^ noted that, when the daily 

 dosage of tocopherol was decreased below 0.75 mg./day, the length of the 

 period of fertility was reduced. McCay and co-workers'*®^ reported that the 

 curtailment of the fertility period in the male and female, as the result of 

 an insufficient intake of vitamin E, did not influence longevity. 



The amount of \'itamin E required daily by rabbits is estimated as 0.2 

 to 0.4 mg. per kg. body weight.^®® The total requirement for the guinea 



^^ E. M. Hume, Nature, 148, 472-473 (1941). 



460a Anonymous, An International Standard for Vitamin E, Nature, 148, 473 (1941). 



«i G. A. Emerson and H. M. Evans, /. Nutrition, 27, 469-476 (1944). 



*62 H. Dam, H. Granados, and L. Prange, Acta Physiol. Scand., 18, 161-170 (1949). 



«»H. M. Bruce, /. Hi/g., 48, 171-183 (1950). 



48* M. Goettsch and A. M. Pappenheimer, J. Nutrition, 22, 463-476 (1941). 



«6 C. M. McCay, G. Sperling, and L. L. Barnes, Arch. Biochem., 2, 469-479 (1943). 



4««S. H. Eppstein and S. Morgulis, J. Nutrition, 22, 415-424 (1941). 



