DIGESTION, ETC. OF FAT-SOLUBLE VITAMINS 313 



vitamin A is much less than in the case of carotene. Schmidt and 

 Schmidt 419 reported that vitamin A could still be efficiently absorbed by 

 choledochocolostomized vitamin A-deficient rats. 



d'. The Effect of Fat Feeding: Fat likewise plays a less important 

 role in the absorption of vitamin A from the gastrointestinal tract than 

 it does in the case of the carotenoids. Although Basu 227 stated that fat 

 is required for the absorption of vitamin A and carotene, contrary results 

 have been reported for the absorption of vitamin A in rats by De 420 as well 

 as by Reifman and associates. 418 The presence of fats was also found to 

 be unessential for the absorption of vitamin A in the fowl, 232 as well as 

 in man. 228 



e'. The Effect of Mineral Oil: The presence of mineral oil in the in- 

 testine may likewise modify the absorption of vitamin A, but here also the 

 effects are less serious than in the case of provitamin A. In fact, Moness 

 and Christiansen, 421 as well as Alexander and co-workers, 268 failed to 

 demonstrate any deleterious effect whatsover on the part of mineral oil 

 on the utilization of vitamin A. 422 However, a number of other 

 workers 269 ' 277 ' 423-425 reported some impairment in the absorption of vita- 

 min A when mineral oil was present, although to a lesser degree than in the 

 case of carotene. 



f. A Comparison of the Utilization of Vitamin A Alcohol and Vitamin 

 A Esters: In general, the absorption of vitamin A has been believed to 

 proceed equally well, in normal subjects, when given as the ester or as the 

 alcohol. 426 ' 427 However, since the hydrolysis of the vitamin A ester to 

 the alcohol must precede its absorption, any conditions which retard or 

 inhibit the hydrolysis of the ester should at the same time reduce the 

 effectiveness of the ester form. Accepting this as a working hypothesis, 

 Week and Sevigne compared the biological responses to vitamin A given 

 in the form of natural esters, acetate or free alcohol when fed to chickens 428 



419 W. Schmidt and C. L. A. Schmidt, Univ. Calif. (Berkeley) Pub. Physiol., 7, 211-221 

 (1930). 



420 N. K. De, Indian J. Mea. Research, 24, 751-766 (1937). 



421 E. Moness and W. G. Christiansen, J. Am. Pharm. Assoc., 18, 997-998 (1929). 



422 A. C. Curtis and P. B. Horton, Am. J. Med. Sci., 200, 102-107 (1040). 



423 O. Andersen, Acta Paediat., 24, -122-427 (1939). 



424 P. B. Hawk, B. L. Oser, and W. H. Summerson, Practical Physiological Chemistry, 

 12th ed., Blakiston, Philadelphia, 1947, p. 1037. 



425 M. C. Smith and H. S. Spector, Univ. Arizona, Coll. Ayr. Ariz. Ayr. Ex pi. Sta., 

 Tech. Bull. No. 84, 373-395 (1940). 



426 A. B. McCoord, C. P. Katsampes. C. F. Lavender, F. J. Martin, R. A. Ulstrom, 

 R. H. Tully, III, and A. J. Keenan, Pediatrics, 2, 652-665 (1948). 



427 A. E. Sobel, L. Besman, and B. Kramer, Am. J. Diseases Children, 77, 576-591 

 (1949). 



428 E. F. Week and F. J. Sevigne, J. Nutrition, 39, 233-250 (1949). 



