EXCRETION OF LIPIDS BY WAY OF LARGE INTESTINE 343 



Although Iwatsura and Nakamura 605 noted that the excreted fat is con- 

 stant even if various types of fat are added to the diet, Cook, 105 in his ex- 

 cellent review on lipid absorption and excretion, pointed out the fact that 

 lipid excretion is slightly increased on a fat-containing diet in a variety of 

 species, as compared with that on a fat-free regimen. These data are sum- 

 marized in Table 1 1 . 



Table 11 



Livid Excretion in the Feces op Several Species on Fat-Low and Fat-Containing 



Diets" 



Total lipid Unsaponifiable matter 



(g./kg.) (mg./kg. ) 



Species Low-fat diet Fat diet Low-fat diet Fat diet 



Rat 6 0.3 0.85 100 200 



Guinea pig 6 1.5 150 



Rabbit 6 0.4 80 



Cat c 0.15 0.2 13 30 



Dog c 0.05 0.1 12 25 



-Man'' 0.05 20 



" Adapted from R. P. Cook, "Comparative Aspects of Lipid Absorption and Excre- 

 tion," in R. T. Williams, Lipid Metabolism, Bioehem. Soc. Symposia, No. it, 14-29, 

 Cambridge Univ. Press, 1952, p. 23. 



6 R. P. Cook and R. O. Thomson, Quart. ./. Exptl. Physiol., 36, 01-74 (1951). 



' \V. M. Sperry ami W. R, Bloor, ./. Biol. Chem., 60, 201-287 (1924). 



d D. C. Edwards and R. 1'. Cook, Unpublished results cited by Cook (footnote a 

 above). 



According to Wollaeger, Comfort, and Osterberg, 606 the increased lipid 

 excretion in the feces following the ingestion of fat can be calculated from 

 the formula y = 2.93 -f- 0.02 l.r, in which x represents the quantity of 

 ingested fat. Thus, it is calculated that, with an intake of 350 g. of fat, 

 as much as 10 g. of lipid would be excreted in the feces. 



Lewis and Partin, 607 reported that the daily fecal excretion of lipids by 

 normal human subjects on a diet practically devoid of fat approximates 

 .3 g. For a man of average weight (70 kg.), this would involve an excretion 

 of 70 mg./kg., which is higher than the value suggested by Cook 105 for 

 human subjects receiving fat diets. Not only does the ingestion of fats 

 cause an increase in fecal lipids, but also, according to Edwards and Cook, 608 

 the fatty acid excretion in the feces is increased in rats fed cholesterol. 

 The fatty acids excreted are those which are normally present. 



605 R. Iwatsura and T. Nakamura, ,/. Bioehem. (Japan). 37. 397-408 (1950). 



606 E. E. Wollaeger, M. W. Comfort, and A. E. Os-terberg, Gastroenterology, 9, 272-283 

 (1947). 



r "' 7 (1. T. Lewis and H. C. Partin, Federation Proc, 12, 239 (1953). 

 60S D. C. Edwards and R. P. Cook, Bioehem. ./., 48, ix (1951 ). 



