292 ESSENTIAL FATTY ACIDS 



data can be found in standard references on the composition of fats and 

 oils, and for more information the reader is referred to them.^"^ 



The highly unsaturated fatty acids are abundant in fish oils such as cod 

 and shark liver oils, but their value as essential fatty acids is doubtful. The 

 structures of some acids isolated from these sources differ from the essential 

 fatty acids in that they have ethylene-interrupted rather than methylene- 

 interrupted polyunsaturated systems. The literature contains a few hints 

 that fish oil acids are toxic to the animal. 



The widespread occurrence of linoleate in vegetable oils and arachidonate 

 in animal tissues makes the possibility of spontaneous fat deficiency unlikely 

 n man or in animals if a natural selection of food is allowed. 



VIII. Effects of Deficiency 



A. IN ANIMALS AND INSECTS 

 RALPH T. HOLMAN 



1. Rat 



The discovery of a fat-deficiency syndrome arose through the attempts 

 of Evans and Burr to produce a synthetic diet free of vitamin E.^ The syn- 

 drome was first recognized and described as fat deficiency by Burr and 

 Burr,- and since then the deficiency has often been called the Burr and 

 Burr syndrome. Simultaneously McAmis ei al. reported a reduced growth 

 on fat-free diets' but did not recognize the essential nature of the fatty 

 acids responsible. These workers were able to produce the deficiency because 

 of their departure from past practice in substituting sucrose for starch 

 as carbohydrate energy source. (Starch contains an appreciable amount 

 of unsaturated fat as a component of the granule.) Using sucrose as energy 

 source and exhaustively extracted casein as protein component, they were 

 able to reduce the fat content of the ration enough to demonstrate fat de- 

 ficiency. Rats maintained on fat-deficient rations reach an early growth 

 plateau, their skin becomes scaly and their coat rough, usually within a 



5 G. S. Jamieson, Vegetable Fats and Oils. Reinhold Publishing Co., New York> 



1943. 

 ^ A. E. Bailey, Industrial Oil and Fat Products. Interscience Publishers, New York, 



1945. 

 B T. P. Hilditch, The Chemical Constitution of Natural Fats, 2nd. ed. John Wiley 



and Sons, New York, 1947. 



1 H. M. Evans and G. O. Burr, Proc. Soc. Exptl. Biol. Med. 24, 740 (1927). 



2 G. O. Burr and M. M. Burr, /. Biol. Chem. 82, 325 (1929). 



3 A. J. McAmis, W. E. Anderson, and L. B. Mendel, /. Biol. Chem. 82, 247 (1929). 



