METABOLISM OF ABSORBED TOCOPHEROLS 699 



found. Thus, when doses of a-, y-, or 5-tocopherol were fed to hens in 

 amounts of 100 to 4,000 mg. Aveek, progressively increasing amounts of 

 the dietary tocopherols were found to be transferred to the egg;^^ the 

 amomit of tocopherol \'aried according to the type fed. When the dosage 

 was 400 mg./week, the relative efficiency of transfer to the egg was 22.1% 

 for the a-tocopherol, 3.6% for the y- variety, and 2.0% for the 5-type.^^-^^^ 

 There is no current information concerning the absorbability of the newer 

 members of the tocopherol family, i.e., e- and f -tocopherols, but one would 

 expect it to be comparable to that of other members of the group. 



5. The Transport of Tocopherols from the Intestine to the Tissues 



The data are extremely limited on the pathwaj^ of transport of absorbed 

 tocopherols from the gut to the blood-stream and the tissues. There is 

 no reason to suppose that the method of transport differs from that of the 

 other fat-soluble vitamins. However, there does not appear to be any 

 information in the literature in regard to the presence of vitamins E in the 

 lymph, or any evaluation of the proportion of these \dtamins carried via the 

 lymph and by the portal system. Harris"^ stated that the rates of ab- 

 sorption or orally-administered \'itamins A and E are sufficienth^ similar 

 to constitute presumptive evidence that the two \'itamins travel from the 

 intestine to the blood-stream by the same pathway. If this is the case, 

 the vitamins E would be carried from the intestinal lacteals in the chyle, 

 and would ultimately be poured into the blood-stream from the thoracic 

 duct. None would be carried via the portal route. 



6. The Metabolism of Absorbed Tocopherols 



(i) The Presence of Tocopherols in Blood 



According to Rosenberg,^"^ the total blood tocopherol averages 5.6 Mg-Z'lO 

 c.c. of serimi in female rats and 6.4 Atg., 10 e.c. serum in male rats when a 

 normal diet is given; however, when tocopherol is administered, the blood 

 level can be increased to 100 Vg- Vitamin E occurs in the blood as the free 

 alcohol, even after the ester has been administered. Quaife et al.^^ re- 

 ported that 75% of the blood tocopherol in man consisted of the a-variety 

 while other types comprised the balance. The total tocopherol contained 



1" P. L. Harris, Personal communkation to the author (March 1954). Cited in Vol. 

 II, The Lipids, p. 336. 



