320 IV. DIGESTION OF LIPIDS OTHER THAN FATS 



The absorption of vitamins D 2 and D ;J has also been proved by the 

 demonstration that the type of vitamin D in egg yolk of hens corresponds 

 to that in the dietary regimen after the feeding of irradiated ergosterol 

 or cod-liver oil. 501,502 Similar variations have been noted by Bethke 

 et a/. 503 in the type of vitamin D in milk as related to its presence in the 

 food. 



(3) Vitamins E {Tocopherols) 



When the tocopherols are given in moderate doses, they are relatively 

 poorly utilized. Although Me Arthur and Watson 504 were unable to 

 prove the presence of any significant amount of the vitamins E in the 

 urine, more recent investigations have indicated that the absorption of 

 these vitamins is not complete, and that definite quantities are excreted 

 in the feces, particularly after large doses. 505 



After feeding a-tocopherol tagged with C 14 in oil solution to rats, 

 Shantz 506 found that only 20% was absorbed, and that the remaining 

 80% was excreted in the feces. These figures are in line with the results 

 of Engel and Heins, 507 who reported that 40% of the vitamin E from 

 wheat germ oil and 87% from dried grass were lost in the feces. On the 

 basis of the finding that the feeding of feces resulted in cure of vitamin E 

 deficiency, Pindborg 508 postulated a synthesis of vitamin E in the intestine. 

 Harris 509 criticized this interpretation; he believes that the fecal vitamin 

 E merely represents unabsorbed vitamin E from the food. Swick and 

 Baumann 282 reported that the maximum concentration of tocopherol 

 occurred in the intestinal wall of the rat five hours after the ingestion of 

 free a-tocopherol, and eight hours after the feeding of a-tocopherol ace- 

 tate. Maximum values were of the same order of magnitude in both cases. 



Considerable differences exist in the ability of the animal to utilize the 

 different tocopherols. This is illustrated in the experiments of Quaifc 



M > R. M. Bethke, P. R. Record, C. H. Kick, and D. C. Kennard, Poultry Sri., 15, 326- 

 335 (1936). 



602 R. M. Bethke. P. R. Record, O. H. M. Wilder, and C. H. Kick, Poultry Sci., 15, 

 336-344(1936). 



603 R. M. Bethke, W. E. Krauss, P. R. Record, and O. H. M. Wilder, J. Nutrition, 11, 

 21-30(1936). 



504 C. S. McArthur and E. M. Watson, Can. Chetn. Process Inds., 23, 350-352 (1939). 

 sot A. Juhdsz-Schaffer, Arch. path. Anat. u. Physiol. (Virchow's), 281, 53-65 (1931) 



606 E. M. Shantz, Unpublished data cited by P. L. Harris, Ann. Rev. Biochem., 18, 

 391-394(1949), p. 410. 



607 C. Engel and J. T. Heins, Acta Previa Neerland. Physiol. Pharmacol. Microbiol., 13, 

 37 (1943). 



608 J. J. Pindborg, Nature, 164, 493 (1949). 



609 P. L. Harris, Nature, 165, 572 (1950). 



