826 XIII. ESSENTIAL FATTY ACIDS 



taken. The latter effect was not believed to be ascribable to the choles- 

 terol present in the ingested animal fats. Although it is uncertain whether 

 or not the vegetable oil effect is to be attributed to the EFA, it is only natural 

 to assume that the variation in the response of the blood cholesterol to 

 vegetable and animal fats is to be traced to this variation in composition. 

 Sinclair^-- considers that human diets in most civilized countries are becom- 

 ing increasingly deficient in essential polyethenoid fatty acids (arachidonic 

 acid), due to hydrogenation and hardening of food fats and to other manu- 

 facturing processes. As a result, the cholesterol in the diet is esterified with 

 abnormal or unusually saturated fatty acids. These abnormal esters are 

 not readily disposed of, and may cause atheroma. Similarly, abnormal 

 phospholipids containing abnormal or unusually saturated fatty acids are 

 less readily disposed of, and are retained in the plasma; they increase the 

 coagulability of the blood, and contribute to coronary and cerebral throm- 

 bosis. 



The importance of the essential fatty acids in relation to atherosclerosis 

 in the rabbit has been clearly demonstrated by Ivritchevsky and co- 

 workers.^-^ Rabbits were fed complete diets containing the following varied 

 lipid components: I, no fats or cholesterol (control group) ; II, cholesterol 

 (3%), corn oil (9%); III, cholesterol (3%), shortening (9%); IV, choles- 

 terol (3%); V, corn oil (9%) ; VI, shortening (9%). The corn oil had an 

 iodine value of 130, and the shortening was a vegetable oil hydrogenated to 

 give a solid fat having an iodine number of 72. After two months, the 

 rabbits were sacrificed and the extent of atherosclerosis was given a mathe- 

 matical score based upon 0, +, + + , + + + , and + + + + , considered 

 as 0, 1, 2, 3, and 4. The follo^^^ng averages were obtained on the state of 

 the atherosclerosis in the several groups: T, 0.06; II, 2.71; III, 3.71; 

 IV, 3.80; V, 0.10; and VI, 0.10. It is thus evident that the feeding of 

 corn oil, which contains a high proportion of essential fatty acids, is able 

 to suppress the deposition of cholesterol in the aorta of rabbits to a marked 

 extent, even when the animals are subjected to such a severe strain as is 

 afforded by the presence of 3% cholesterol in the diet. On the other hand, 

 the shortening did not appear to alleviate the condition. These data like- 

 wise refute the concept that fat 'per se has an atherogenic effect. 



"2 H. M. Sinclair, Lancet, 1956, 1, 381-383. 



223 D. Kritchevsky, A. W. Moyer, W. C. Tesar, J. B. Logan, R. A. Brown, M. C. 

 Davies, and H. R. Cox, Am. J. Physiol., 178, 30-32 (195-1). 



