CHAPTER XIII 



THE PHYSIOLOGY AND BIOCHEMISTRY 

 OF THE ESSENTIAL FATTY ACIDS 



1. Introduction 



A number of physiologic functions depend more or less upon the fat 

 content of the organism for an efficient performance. Whether some of 

 these functions depend upon the general fat molecule per se or rather upon 

 certain fatty acid components is a moot question. In the present chapter 

 the physiologic reactions which can be definitely traced to certain poly- 

 unsaturated fatty acids are discussed. The first investigation which 

 proved that the rigid exclusion of fats from the diet results in a fat-defi- 

 ciency syndrome was that of Evans and Burr in 1926.^ This w^as followed 

 shortly thereafter by a report of a similar syndrome observed by McAmis 

 and her co-workers,- who demonstrated that rats receiving fats in their 

 diets grew better than did animals on a fat-free regimen. The final proof 

 that the lack of fat produces a deficiency disease was brought forward by 

 Burr and Burr,^ who also demonstrated that the condition could not be 

 ascribed to the lack of fat-soluble vitamins. In a further study of this 

 new fat-deficiency disease, Burr and Burr^ showed that the deficiency 

 symptoms disappeared immediately when lard, cod-liver oil, corn oil, or 

 linseed oil was fed. The curative agents were found to be present in the 

 saponifiable fraction. The highly unsaturated acids, linoleic, linolenic, 

 and arachidonic acids, were excellent curative agents, while saturated 

 acids such as stearic, palmitic, myristic, lauric, and those with shorter 

 chain lengths were found to possess no biologic activity. Thus, coconut 

 oil, hydrogenated coconut oil, and methyl stearate gave completely nega- 

 tive results.^ The fact that the polyunsaturated acids might be the active 



1 H. M. Evans and G. O. Burr, Proc. Soc. Exptl. Biol. Med., 2-',, 740-743 (1926- 1927). 



2 A. J. McAmis, W. E. Anderson, and L. B. Mendel, J. Biol. Chem., 82, 247-262 

 (1929). 



3 G. O. BvuT and M. M. Burr, /. Biol. Chem., 82, 345-3G7 (1929). 

 * G. O. Burr and M. M. Burr, J. Biol. Chem., 86, 587-621 (1930). 

 5 G. O. Burr, Federation Proc, 1, 224-233 (1942). 



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