Factors Affecting the Requirement for Essential Fatty Acids

Factors Affecting the Requirement FOR Essential Fatty Acids 

Although the discovery of the requirement for EFA as a dietary constituent was first made on the rat, and considerable information has been obtained by the study of this species, the necessity of these acids has been found to be very widespread. Fraenkel and Blewett (1946) demonstrated that the EFA are required by certain insects, such as the Mediterranean flour moth (Ephestia kUhniella), the tobacco moth (E. eiUdla), the fig moth (E. cautella), and the Indian-meal moth Phdia interpunctella (Lep.)). 

Mice develop a deficiency similar to that of rats on regimens devoid of EFA (White et al, 1943) in fact, this species has recently been used by Decker et al (1950) for a comprehensive study of EFA. Although Russell and co-workers (1940) were unable to provoke a fat deficiency in chickens, Reiser (1950a) was later successful in producing the deficiency in this species. In the latter tests, sucrose was used in the diet in place of the ground yellow corn employed by Russell et al (1940). It was suggested that, in the earlier tests, there was a sufficient supply of EFA, chemically combined with the starch particles and not removed by the usual methods of extraction, to prevent EFA deficiency. 

The hog represents a species relatively refractory to EFA deficiency. The failure to induce a fat deficiency in this species may be related to the high content of EFA frequently stored in its tissues. Thus, Ellis and Isbell (1926a,b) noted that lard from hogs on a high-soybean diet sometimes had a linoleate content as high as 31.9%. When the animals were subjected to a fat-free diet, it was found that the linoleate content decreased to as little as 1.3% (Ellis and Zeller, 1930). It would appear to 

The dog represents a species which is readily susceptible to the fat-deficiency syndrome. Because of the convenient size of this species, which will enable a clinical study to be made on one animal over a period of time, considerable work has been reported on EFA deficiency in these animals. Hansen and Wiese (1943) first demonstrated that the symptoms of fat deficiency in the dog are similar to those produced by fat-free diets in other species. It has been suggested that dietary fat may supply a factor necessary for the maturation of epithelial, sebaceous, and sudoriparous cells. The fat-deficiency symptoms in the dog were found to respond quickly to a diet containing fresh lard to the extent of 29% of the total calories (Hansen and Wiese, 1943, 1951). 

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V. Factors Affecting the Requirement for Essential Fatty Acids. 43... 

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