General Discussion 193 



human being. Perhaps he would also review the role of essential 

 fatty acids in cholesterol metabolism. 



Nicolaysen: I am quite optimistic both as regards animal and 

 human studies provided they are planned and executed. Out of 

 human pathology comes, as we all know, much valuable inspiration 

 for fundamental studies in animals ; and vice versa, carefully planned 

 work on animals — on isolated organs, tissues and single cells — is 

 fundamental in physiology. Any number of valuable results from 

 such animal work is, in fact, the very basis of modern medicine. 



I think we shall profit by following the same pattern, i.e. work on 

 animals and man ; however, results achieved in animals must, 

 whenever possible, be tried out for validity in the human species. 

 Since the science of nutrition is a true child of physiology and bio- 

 chemistry the above would, in my opinion, apply generally irre- 

 spective of age. Species differences can be elucidated without too 

 much difficulty. 



The Chairman's question caught me somewhat unaware, when he 

 asked me if I would review briefly the rather exciting problem 

 concerning the role of essential fatty acids in cholesterol metabolism. 

 It might therefore serve a useful purpose to take this problem to 

 illustrate what I mean. 



Considerable sensation has been caused by the recent achievements 

 in the field of cholesterol metabolism. In fact, it has been postulated 

 that essential fatty acids are responsible for normal cholesterol 

 transport and that the deficiency of these acids is responsible for 

 cholesterol accumulation and deposition in the arterial walls. The 

 implication has been that this new knowledge, properly applied in 

 human dietetics, would be instrumental in preventing atherosclerosis 

 and, in consequence, coronary thrombosis and cerebral infarction — 

 the two diseases responsible for about one-third of all deaths in our 

 countries. This rests on the assumption that the incidence of coronary 

 thrombosis and of cerebral infarction is intimately correlated to the 

 severity of the atherosclerosis. However, competent clinicians will 

 deny this and they focus attention primarily on the thrombosis 

 problem. On the other hand, it seems to be generally accepted that 

 thrombosis will not develop in arteries free from cholesterol plaques. 

 However, it may be of value to recall some analytical data regarding 

 different fats and their effect on blood cholesterol. 



An oil such as olive oil contains about 9 per cent of essential fatty 

 acids and depresses blood cholesterol. Lard, on the other hand, 

 increases blood cholesterol ; it contains 7 per cent of essential fatty 

 acids. It is even more puzzling that egg yolk, which increases blood 

 cholesterol very markedly, contains 60 per cent of fat as dry matter 

 with 18-19 per cent of essential fatty acids in the fat. 



ageing — m— 7 



