DIGESTION, ETC. OF FAT-SOLUBLE VITAMINS 325 



amount of vitamin D was excreted in the bile of the drisdol-treated dogs, 

 while practically no vitamin D was found in the bile of the dogs receiving 

 the viosterol injection. 



In certain cases, vitamin D has been shown to be excreted in the feces. 

 After obstruction of the common bile duct in dogs, a single dose of vitamin 

 D administered as viosterol or drisdol resulted in its excretion in the feces 

 for only ten to sixteen days. 494 On the other hand, when such dosages 

 of vitamin D were given to normal dogs, vitamin D was found in the feces 

 eight months after viosterol and at least six months after drisdol had 

 been given. Moreover, parenterally administered viosterol or drisdol 

 was shown to be excreted in the feces of dogs in which the bile flow or that 

 of pancreatic juice had been excluded from the intestine. Heymann 494 

 believes that this indicates that a portion of the vitamin D is normally 

 excreted through the intestinal wall. The largest percentage of the 

 vitamin is eliminated by the first third of the small intestine. 



The presence of mineral oil has been shown in most cases to reduce the 

 absorption of vitamin D. Although Dutcher el a/. 495 and Jackson 496 

 could not demonstrate that mineral oil exerted any deleterious effect on 

 the absorption of vitamin D, more recent studies of vSmith and 

 Spector 425 ' 497,498 indicated that mineral oil interferes markedly with the 

 absorption of vitamin D, both in rats and in dogs. 



It must be inferred that vitamin D esters are hydrolyzed in the intestine 

 prior to absorption. Windaus and Rygh 499 have shown that those esters 

 of vitamin D which are incapable of hydrolysis have no antirachitic 

 potency. It has not been established whether the non-utilization of 

 such esters is to be ascribed to their failure to be absorbed or to their 

 biological inactivity after absorption in the conjugated form. 



No differences in absorption of the different vitamins D have been noted 

 in normal dogs. Morgan and Shimotori 500 found that equal protection 

 from rickets could be noted in dogs receiving vitamin D 2 , vitamin D 3 , 

 or a tuna liver oil, after a single dose of 20,000 units. When a single 

 massive dose containing 200,000 units was given, symptoms of prostration 

 were observed with both vitamins D> and D 3 . 



494 W. Heymann, J. Biol. Chem., 122, 257-262 (1937-1938). 



495 R. A. butcher, J. O. Ely, and H. E. Honeywell, Proc. Soc. Exptl. Biol. Med., 24, 

 953-955 (1927). 



496 R. W. Jackson, ,/. Nutrition, 7, 617-622 (1934). 



497 M. C. Smith and H. Spector, /. Nutrition, 20, 19-30 (1940). 



498 M. C. Smith and H. Spector, ./. Nutrition. 20, 197-202 ( 1940). 



499 A. Windaus and O. Rygh, Nachr. Ges. Wis*. Gottingen, Math.-physik. Klasse, III, 

 .'02-216(1928). 



600 A. F. Morgan, and N. Shimotori. ./. Biol. Chem., l/,7. 1X9-200 (1943). 



