878 XIV. NUTRITIONAL VALUE OF FATS 



minished. Calcium and magnesium were shown to ha^•e a progressive 

 effect. That is, the larger the amount present in the diet the greater the 

 depression in digestibility of the fat and the larger the proportion of soap 

 eliminated in the feces. 



The proportion of calcium lost in the stool or, conversely, the amount of 

 fatty acid which fails to be absorbed because it is excreted as a calcium 

 soap, has also been shown to vary with the type of fat. Thus Steggerda 

 and MitchelP'^^ found that, in the case of milk fat, the calcium metabolism 

 was not affected by the proportion of butterfat present in the diet. On 

 the other hand, when cocoa butter was employed,"- it was found that the 

 average calcium utilization by rats was decreased from a level of 73.9% 

 for a low-fat diet, or 72.1% for a 20% lard diet, to a value of only 57.6% 

 for a 20% cocoa butter diet. It is believed that the inhibiting effect of 

 cocoa butter on calcium utilization is in this case largely or entirely ac- 

 counted for by the greater formation of insoluble calcium soaps. 



Rao and De"^ reported that the inclusion of 10% of coconut oil con- 

 taining both the saturated and the unsaturated fatty acid fraction in a 

 normal diet increased the utilization of calcium in young growing rats. 

 However, the excretion of calcium in the urine was only indirectly affected 

 by the presence of fat in the diet. Thus, when the fecal excretion of cal- 

 cium was considerably increased, there was a decrease in the urinary elim- 

 ination of the metabolite. 



(11) The Effect of Dietary Fat upon Vitamin Requirements 



a. Thiamine and Fat. It was recognized by Evans and Lepkovsky"^ 

 that, on diets adequate except for their content of vitamin Bi, the onset of 

 polyneuritic symptoms was retarded on high-fat diets. On the other 

 hand, when carbohydrate diets were employed, polyneuritis developed at 

 an accelerated rate. It was found that many vegetable and animal fats 

 were equally efficacious in retarding the onset of avitaminosis. Thus, 

 lard, coconut oil, synthetic coconut oil, hydrogenated coconut oil, partially 

 hydrogenated cottonseed oil (Crisco), cottonseed oil, and perilla oil were 

 all effective. i^^'"« 



The only fat which did not possess a thiamine-sparing action was hy- 

 drogenated perilla oil."^ This substance was poorly absorbed"^ and, 



>" F. R. Steggerda and H. H. Mitchell, /. Nutrition, 45, 201-211 (1951). 



1" J. R. Beadles, H. H. Mitchell, and T. S. Hamilton, /. Nutrition, 45, 399-405 (1951 ). 



"3 M. N. Rao and S. S. De, Ind. J. Med. Research, 40, 235-242 (1952). 



"4 H. M. Evans and S. Lepkovsky, Science, 68, 298 (1928). 



"5 H. M. Evans and S. Lepkovskv, J. Biol. Chem., 92, 615-622 (1931 ). 



"6 H. M. Evans and S. T.epkovskv, /. Biol. Chem., 96, 165-177 (1982). 



