884 XIV. NUTRITIONAL VALUE OF FATS 



protein metabolism because of deficient transamination and decarboxyla- 

 tion. Moreover, it is believed that the skin lesions in EFA deficiency 

 allow the water to pass through the skin more readily than normally, 

 whereas in pyridoxine deficiency an inadequate amount of histaminase is 

 present, with a resultant incomplete destruction of histamine. 



Another indication that EFA deficiency and acrodynia result from two 

 different types of deficiency is the fact that the liver dehydrogenases vary 

 according to the nature of the deficiency. Thus, Tulpule and Patward- 

 han^oa reported that, whereas the level of succinic dehydrogenase was 

 not affected in pyridoxine deficiency, its activity was reduced in the liver 

 in EFA deficiency, or in combined EFA and pyridoxine deficiencies. 

 Furthermore, the amount of butyric dehydrogenase in the liver was de- 

 creased in EFA deficiency, while it was unchanged when pyridoxine was 

 lacking in the diet. Combined EFA and pyridoxine deficiency did not 

 reduce the activity of butyric dehydrogenase any further. On the other 

 hand, either EFA or pyridoxine deficiency significantly decreased the 

 glutamic dehydrogenase in the liver. It is postulated that the higher 

 saturation of the fatty acids in the fiver which occurs in EFA or pyridoxine 

 deficiency is to be ascribed to a decrease in the desaturating capacity of 

 the liver or to interference with the metabohsm of other compounds from 

 which unsaturated fatty acids are derived. 



When a low content of dienoic acid was produced in the tissues of rats 

 by the withdrawal of EFA from the diet or by the exclusion of pyridoxine 

 or thiamine from the diet, coupled w^th a severe caloric restriction, charac- 

 teristic EFA deficiency symptoms were observed only in the first case. 2"" 

 This led Medes and co-workers^^" to conclude that pyridoxine exerts no 

 special supplementary action on the production or conservation of EFA. 



According to McHenry and Gavin, ^^^ ^^^ pyridoxine is a factor required 

 by the mammal for the synthesis of fat. Therefore, larger amounts are 

 apparently required in the diet when preformed fat is not fed, and it must 

 be produced in the body itself. 



Sherman^i^ reviewed the interrelationship of pyridoxine and fat me- 

 tabolism. 



e. Niacin, Folic Acid, Biotin, Vitamin B12, and Fat. Since both niacin 

 and folic acid are synthesized in the intestine of the rat, it is logical to 



203 P. G. Tulpule and V. N. Patwardhan, Arch. Biochem. Biophys., 39, 450-456 (1952). 



210 G. Medes, M. V. Mann, and J. B. Hunter, Arch. Biochem. Biophys., 32, 70-79 

 (1951). 



211 E. W. McHenry and G. Gavin, J. Biol. Chem., 138, 471-475 (1941). 



212 E. W. McHenry and G. Gavin, J. Biol. Chem., 125, 653-660 (1938). 



213 H. Sherman, Vitamins and Hormones, 8, 55-68 (1950). 



