FATS AS ESSENTIAL DIETARY COMPONENTS 877 



content of the liver are significantly diminished in rats fed skim milk, the 

 cerebroside content of the brain of rats fed skim milk (jr whole milk, 

 respectively, did not differ significantly. Moreo^•cr, the urinai-y excretion 

 of galactose by the skim-milk-fed rats might l)e due to the non-conversion 

 of galactose into glycogen in the liver under such conditions. In <-ontra- 

 distinction to rats, rabbits fed skim milk for two months did not excrete 

 galactose in the urine. 



{10) The Effect of Dietary Fat upon Calcium Utilization 



It has become increasingly evident in recent years that an interrelation- 

 ship exists between the utilization of calcium and that of fat. Thus, 

 certain high-fat diets may decrease the utilization of calcium, whereas 

 in an analogous manner high-calcium diets may reduce the utilization of 

 fats. Givens^^^ reported that, when the absorption of fats or of fatty 

 acids was poor, the excretion of fecal calcium Avas increased. In fact, they 

 found that the calcium storage was decreased to a great extent under 

 such conditions, even when the calcium intake was kept at a comparatively 

 high level. In investigating this condition Bosworth and co-workers^^^ 

 concluded that the presence and composition of calcium compounds in 

 the intestine are the determining factors in soap formation, and that the 

 amount of calcium ultimately excreted in the feces also depends upon the 

 solubility of the soap formed. These w^orkers suggested that calcium 

 oleate is more readily soluble in bile than is calcium palmitate or calcium 

 stearate. Therefore, when the fats consist largely of oleic acid, calcium 

 would have a less depressing effect upon the absorption of the fatty acids 

 than when palmitic and stearic acids were the predominant fatty acids. 

 Boyd, Crumm, and Ljmian^^^ arrived at essentiallj^ similar conclusions on 

 the basis of experiments on rats, although they found that palmitic acid 

 calcium soaps were also well utilized. In a further investigation of this 

 problem, Cheng, Morehouse, and Deuel^"^ reported that, although the 

 presence of calcium and magnesium in the diet did not influence the di- 

 gestibility of low-melting fats, it markedly decreased that of the higher- 

 melting simple triglycerides and hydrogenated fats. In the absence of 

 calcium in the diet, the proportion of soap in the feces w-as markedly di- 



1" M. H. Givens, /. Biol. Chem., SI, 441-444 (1917). 



168 A. W. Bosworth, H. I. Bowditch, and L. A. Giblin, Am. J. Diseases Children, 15, 

 397-407(1918). 



169 O. F. Boyd, C. L. Crumm, and J. F. Lyman. J. Biol. Chem., 95, 29-41 (1932). 



"0 A. L. S. Cheng, M. G. Morehouse, and H. J. Deuel, Jr., /. Nutrition, 37, 237-250 

 (1949). 



