3J(> IV. DIGESTION OF LIPIDS OTHER THAN FATS 



given in the form of natural esters as when employed in the form of the 

 alcohol (8. 1 % vs. 32.8% of that administered) . When the jojoba oil fed was 

 reduced to one-twentieth of this level (0.1 ml. instead of 2.0 ml. for each 

 feeding), the variations in vitamin A deposition as related to the form of 

 the vitamin A largely disappeared. It is therefore difficult to escape the 

 conclusion that the vitamin A esters must have a markedly lower absorp- 

 tion in chickens than do the alcohols when given in large quantities of oil, 

 particularly when such diluent oils are difficultly absorbed. March and 

 co-workers 430 have also reported that the carrier influences the effectiveness 

 of the form in which vitamin A is administered. When an aqueous carrier 

 was employed, the natural ester and the acetate were found to be better 

 utilized by the chick than was the free alcohol. On the other hand, 

 when cottonseed oil was the carrier, the best utilization obtained with the 

 acetate, followed in order by the alcohol and the natural ester. The low 

 utilization of the palmitate ester of vitamin A in an oil carrier was found 

 to be due not to the destruction of vitamin A but rather to an interference 

 with the absorption of vitamin A through the intestinal mucosa. 



The results obtained in the tests on chickens were shown to apply to a 

 somewhat lesser extent to rats. 429 Jojoba seed oil was found to have a 

 definite depressing action on vitamin A absorption only when the vitamin 

 was given as the natural ester. Week and Sevigne 431 suggest that mineral 

 oil and ethyl laurate contain factors which inhibit the hydrolysis of vita- 

 min A esters in vivo. 



In recent work of Week and Sevigne, 432 it was found that the earlier 

 data obtained in chickens and rats may also apply to man. After a dose 

 of 134,000 jug- of vitamin A in 50 g. of margarine was given to male sub- 

 jects, it was found that the vitamin A absorption, as judged by the vita- 

 min A tolerance curves in the blood, was best with the alcohol, somewhat 

 less with the vitamin A acetate, and poorest with the mixture of natural 

 ester. In the case of female subjects, the vitamin A alcohol yielded a 

 significantly better result than did the vitamin A acetate, while no sig- 

 nificant differences could be noted between the response of the vitamin A 

 in alcohol and in the natural ester form. The results of Popper et al. i3Z 

 on hospital controls and on patients with liver disease differ somewhat 

 from those of Week and Sevigne. 432 When vitamin A was given in either 

 an aqueous or an oily menstruum, the plasma levels were slightly higher 



430 B. E. March, E. English, and J. Biely, Arch. Biochem. Biophys., 86, 259-268 (1952). 

 481 E. F. Week and F. J. Sevigne, /. Nutrition,, 1>2, 525-537 (1950). 

 432 E. F. Week and F. J. Sevigne, J. Nutrition, 40, 563-576 (1950). 

 43S H. Popper, F. Steigmann, and H. A. Dyniewicz, Proc. Soc. Exptl. Biol. Med., 73, 

 188-190(1950). 



