172 II. DIGESTION AND ABSORPTION OF FATS 



shown to approach that obtained in the fatty acid tests. When lipolysis 

 was inhibited by hexadecyl sulfate, the opposite effect was observed. 

 Frazer 809 had shown earlier that the administration of lipase to human 

 subjects caused a considerable reduction in the postabsorptive lipemia. 



Auld and Needham 810 have recently recorded a similar result in the case 

 of a patient with non-traumatic chylothorax. When fats stained with 

 Sudan III were fed to this man, a substantial amount of the dye was re- 

 covered from the chylothorax. On the other hand, when Sudanized fatty 

 acid was given together with glycerol, no dye was recovered in one instance, 

 and only a small amount in a second test. These results are interpreted as 

 supporting the Frazer hypothesis. Although this evidence would appear to 

 be quite convincing in establishing different pathways for the absorption 

 of triglycerides and fatty acids, opposite results have been obtained re- 

 cently on rats by Bloom and associates, 787,790 by Borgstrom, 788 as well as by 

 Reiser and Bryson. 811 



(5) Current Status of Theories of Fat Absorption 



Undoubtedly certain aspects of fat absorption are best explained by the 

 Lipolytic Theory, and other features of fat utilization seem to support the 

 Partition Theory. Both of these hypotheses have merit, and it seems prob- 

 able that eventually a new theory will be propounded which includes the 

 salient features of both concepts. 



8. The Rate of Absorption of Common Fats 



The rate of absorption of fat is an important index of its nutritional value. 

 Although no differences may be observed between the total quantities of 

 two fats which can be utilized, as determined from digestibility studies, 

 when the fats are taken in moderate amounts, an entirely different picture 

 may be obtained if they are fed in large doses. Thus, the maximum amount 

 of a fat which may be taken without causing a digestive disturbance varies 

 widely. If the fat is one which is slowly absorbed, diarrhea may occur on 

 the administration of relatively small quantities ; in the case of a fat having 

 a more rapid rate of absorption, a greater tolerance obtains before the onset 

 of diarrhea. It is therefore evident that absorption rates and digestibility 

 coefficients, although related, afford information on independent physio- 

 logical responses to fat. 



809 A. C. Frazer, /. Physiol, 102, 329-333 (1943). 



810 W. H. R. Auld and C. D. Needham, Lancet, 260, 991-993 (1951). 



811 R. Reiser and M. J. Bryson, J. Biol. Chan., 189, 87-91 (1951). 



