DIGESTION, ETC. OF STEROLS IN THE G.I. TRACT 265 



of both free and esterified cholesterol obtained. Although these results 

 are interpreted by Bloor 87 as evidence that cholesterol aids in fat absorp- 

 tion, they may as readily be construed as indicative of the role of cholesterol 

 in fat transport after the absorption of the fatty acids from the gastro- 

 intestinal tract has been completed. 



c. Balance Experiments with Cholesterol. The problem of cholesterol 

 utilization has been attacked by the use of balance experiments. The 

 whole picture of cholesterol absorption is complicated by the fact that 

 cholesterol may be destroyed or converted into other steroids, that it may 

 be synthesized in the tissues, and that it is excreted into the gastrointestinal 

 tract through the bile or via the intestinal mucosa. 



The results of Kusumoto, 88 who could account for only 70% of the in- 

 gested cholesterol in the feces, are likewise interpreted as evidence of 

 cholesterol absorption, 87 but it is possible to explain this 30% loss by bac- 

 terial destruction in the gastrointestinal tract. Destruction of cholesterol 

 has been demonstrated in the chicken b}' Dam, 89 and by Page and Men- 

 schick in rabbits 90 and in cats. 91 The results of Schonheimer, 92 based 

 upon the study of a case of hypercholesteremia in man, likewise indicate 

 the probable destruction by the human subject. In a later publication, 

 Schoenheimer and Breusch 93 demonstrated that destruction of chole- 

 sterol occurs in mice; since the extent of destruction is increased when bile 

 acids are given, it is believed that the increased disappearance of chole- 

 sterol results from increased absorption. In othei Avords, it is indicated 

 that the degradation of cholesterol is a function of the tissues, and occurs 

 there rather than in the gastrointestinal tract. Similar conclusions can 

 also be drawn from the results of Cook. 94 



The role played by the intestinal bacteria has been the subject of ex- 

 tensive investigation. A number of workers 95-98 have suggested that 

 the intestinal flora are primarily responsible for the destruction of chole- 

 sterol. Rosenheim and Webster 99 concluded that it is improbable that 



87 W. R. Bloor, Biochemistry of the Fatty Acids, Reinhold, New York, 1943. 



88 C. Kusumoto, Biochem. Z., U, 411-415 (1908). 



89 H. Dam, Biochem. Z., 232, 269-273 (1931). 



90 I. H. Page and W. Menschick, J. Biol. Chem., 97, 359-368 (1932). 



91 W. Menschick and I. H. Page, Z. physiol. Chem., 218, 95-103 (1933). 



92 R. Schonheimer, Z. klin. Med., 123, 749-763 (1933). 



93 R. Schoenheimer and F. Breusch, J. Biol. Chem., 103, 439-448 (1933). 



94 R. P. Cook, Biochem., J., 31, 410-415 (1937). 



96 S. Bondzyriski and V. Humnicki, Z. physiol. Chem., 22, 396-410 (1896-1897). 



96 R. Schonheimer, H. v. Behring, R. Hummel, and L. Schindel, Z. physiol. Chem., 

 192, 73-76 (1930). 



97 S. J. Thannhauser, Klin, Wochschr., 13, 161-167 (1934). 



98 H. Dam, Biochem. J., 28, 820-825 (1934). 



