316 ESSENTIAL FATTY ACIDS 



acrodynic potency of various seed oils is related to the linoleic acid content, 

 except when the linolenic acid content is high, in which case less effect than 

 expected is obtained. ^^ Earlier studies^^' ^^ indicated that ethyl linoleate has 

 no sparing action on pyridoxine, or that both are necessary for complete 

 cure. In rats on a diet deficient in both pyridoxine and essential fatty acids, 

 pyridoxine or linoleic acid supplements are equally effective in permitting 

 growth,^* and the content of highly unsaturated fatty acids increases in rats 

 regardless of which supplement is given. When chicks deficient in vitamin 

 E are fed different fractions of hog liver fatty acids, the most highly un- 

 saturated fraction is the most toxic, ®^ and unsaturated fatty acids increase 

 symptoms of vitamin E deficiency in chicks.®^ Vitamin E-deficient rats 

 given unsaturated fatty acids show a diffuse brown pigmentation of stored 

 fat, together with a lack of the normal pigment of the incisors which is due 

 to iron.^^ The pigmentation of lipids is taken to indicate^* a metabolic 

 interrelation of vitamin E and the essential fatty acids. Vitamin E increases 

 symptoms of essential fatty acid deficiency but potentiates strongly with 

 the effects of unsaturated fatty acids in counteracting this deficiency. ^^ 



D. ACTION ON PHYSIOLOGIC PROCESSES 



The essential fatty acids are necessary for normal reproduction and lacta- 

 tion in the rat.'^"''^^ The comparative potencies of the actions of methyl 

 arachidonate and methyl linoleate on growth are different from relative 

 curative effects on other disturbances in essential fatty acid deficiency in 

 rats.'^^' '^^ Very small amounts of methyl linoleate greatly increase fat storage 

 in the rat.''^ 



If linseed meal is added to an otherwise adequate diet, chicks show in- 



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