FACTORS AFFECTING THE REQUIREMENT 807 



excretion of fatty acids in the feces of rats fed mineral oil. In addition, 

 the fecal fatty acids were found to have an increased iodine value after 

 the ingestion of mineral oil. However, it is believed that this effect cannot 

 be ascribed solely to the solvent action of the hydrocarbon on EFA, since 

 the deficiency symptoms were pre\"ented by the administration of linoleate 

 either orally or intraperitoneally. 



(4) The Effects of Vitamins and Hormones 



Although the metabolism of most of the water-soluble B vitamins is 

 interrelated with that of fat in general, it was pointed out by Salmon '^^ 

 that the deficiencies in pantothenic acid, pyridoxine, and EFA, respectively, 

 result in the production of forms of dermatitis which are similar in appear- 

 ance. The closest relationship appears to exist between the requirement for 

 fat and that of pyridoxine, according to Hogan and Richardson,''*^ and Birch 

 and Gyorgy.^'*^ The dermatitis which occurs on a diet low in pyridoxine 

 but containing 10% of fat can be cured when a small amount of lard is 

 added to the diet.'''^ Birch '■^'^ later showed that the onset of dermatitis 

 due to a pyridoxine deficiency was delayed by the addition of fat to the 

 diet; in some cases, the abnormal skin condition was completely prevented. 



Most of the evidence points to the fact that the effectiveness of fats in 

 counteracting the dermatitis caused by pyridoxine deficiency is proportional 

 to the unsaturation, i.e., presumably to the EFA content. This explana- 

 tion would account for the fact that lard is effective in alleviating pyridox- 

 ine deficiency, since it is ordinarily relatively high in arachidonic and 

 linoleic acids, whereas butter, which has a relatively low content of EFA, 

 is somewhat less efficacious. Schneider'^^ ascribed the low antidermatitis 

 potency of rancid butter to the destruction of the antidermatitis factoi 

 (later identified as linoleic acid) during the course of rancidification. 



All of the principal components of the EFA are capable of curing pyri- 

 doxine deficiency. According to Quackenbush et al.'^^'^ linoleic acid is the 

 most effective of the three principal EFA in alleviating the deficiency symp- 

 toms due to the lack of pyridoxine. Salmon'^" found that the methyl 

 esters of linoleic and linolenic acid are less effective than the oils or their 



"* W. D. Salmon, /. Biol. Chem., I40, cix-cx (1941). 

 "s A. G. Hogan and L. R. Richardson, Nature, 136, 186 (1935). 

 "«T. W. Birch and P. Gyorgy, Biochem. J., SO, 304-315 (1936). 

 i"T. W. Birch, J. Biol. Chem., 124, 775-793 (1938). 

 '« H. A. Schneider, Proc. Sac. Exptl. Biol. Med., 44, 266-267 (1940). 

 1" F. W. Quackenbush, F. A. Kummerow, and H. Steenbock, ,/. Nutrition, 24, 213-224 

 (1942). 



'=0 W. D. Salmon, ./. Biol. Chem., 133, civ-cv (1938). 



