318 ESSENTIAL FATTY ACIDS 



X. Requirements 



RALPH T. HOLMAN 

 A. OF ANIMALS 



The daily linoleic acid requirement for maximum growth of rats has been 

 variously set at 20 to 100 mg.^"^ The prophylactic dose of linoleic acid 

 seems to be of the order of 20 mg. per day. Using highly purified diet, Mac- 

 Kenzie el al.^ found that 23 mg. of methyl linoleate per day was sufficient 

 to allow normal growth and reproduction. Greenberg ei at? found that the 

 daily dietary requirement for the male rat was in the range of 50 to 100 

 mg. of linoleic acid, whereas the female requires between 10 and 20 mg. 

 They also found that linolenic acid, if sparked by some linoleic acid, had 

 growth-promoting activity equal to that of linoleic acid. However, Deuel 

 et al} found that 10 % cottonseed oil in the diet of rats receiving an optimum 

 level of linoleate gave added growth, indicating the possibility of a benefi- 

 cial effect of oil itself or of some constituent of the oil. 



The linoleic acid requirement varies with the composition of the diet. 

 Rations including corn starch or rice starch fail to produce fat deficiency" 

 because of unsaturated fatty acids bound in the starch granules. Diets con- 

 taining saturated fats as the sole source of energy accentuate fat defi- 

 ciency.'" When Sinclair fed trielaidin fs dietary fat, the deficiency symp- 

 toms could not be cured by a daily dose of 20 mg. of corn oil.'' These 

 scattered observations suggest that either the requirement for linoleic acid 

 is increased when non-essential fat is metabolized, or that some synthesis 

 of essential fatty acids is possible from sucrose. 



Several early studies seemed to indicate that tissue linoleic acid parallels 



' G. O. Burr and M. M. Burr, J. Biol. Chem. 86, 587 (1930). 



2 0. Turpeinen, J. Nutrition 15, 531 (1938). 



3 G. 0. Burr, J. B. Brown, J. P. Kass, and W. O. Lundberg, Proc. Sac. Exptl. Biol. 

 Med. 44, 242 (1940). 



^ E. M. Hume, L. C. A. Nunn, I. Smedley-Maclean, and H. H. Smith, Biochem. J. 

 32, 2162 (1938). 



5 E. M. Hume, L. C. A. Nunn, I. Smedley-Maclean, and H. H. Smith, Biochem. J. 

 34, 879 (1940). 



«C. G. MacKenzie, J. B. MacKenzie, and E. V. McCoUum, Biochevi. J. 33, 935 

 (1939). 



' S. M. Greenberg, C. E. Calbert, E. E. Savage, and H. J. Deuel, Jr. /. Nutrition 

 41, 473 (1950). 



8 H. J. Deuel, S. M. Greenberg, C. E. Calbert, E. E. Savage, and T. Fukui, /. Nutri- 

 tion 40, 351 (1950). 



9H. M. Evans and S. Lepkovsky, J. Biol. Chem. 96, 143 (1932). 



i» H. M. Evans and S. Lepkovsky, /. Biol. Chem. 96, 157 (1932). 



11 R. G. Sinclair. /. Nutrition 19, 131 (1940). 



