Effects of Diet on Blood Lipids In Man

Abstract

1. Lipids exist in the blood serum as emulsions ("chylomicrons") and as solutions of lipoprotein containing proteins, cholesterol, and other lipids. Interest in relation to atherosclerosis is centered on the cholesterol and the beta lipoproteins which contain most of the cholesterol. 2. The diet influences the blood lipids in man and animals but great quantitative differences between species makes it essential to study man himself to discover the effects of the diet on the blood lipids in man. 3. The amount of lipid in the chylomicron form in the serum is practically independent of the concentration of cholesterol and lipoproteins in the serum. The correlation between the concentrations of alpha and beta lipoproteins is very low. 4. Experiments on man show that dietary cholesterol per Se, even in large amount, has no important influence on the serum cholesterol concentration but that the latter is markedly affected by the total fat content of the diet. 5. Calorie intake per se has little influence on the blood lipids. Such effect as it has may be secondary to fat metabolism differences commonly associated with differences in calorie intakes. 6. Studies on population samples of healthy men show a marked direct relationship between the content or proportion of fat in the diet on the one hand and the concentration of total cholesterol and of beta lipoproteins in the serum on the other. The effect of the diet tends to be greater in middle-aged men than in younger men. 7. The average concentration of cholesterol in the serum of men in areas where the diets are very high in fats (of the order of 40 per cent of calories), is 25 to 50 per cent greater than the average in areas where the diets are low in fats (of the order of 20 per cent, or less, of calories). 8. A significant effect of dietary fat level on the serum cholesterol concentration is evident in man in a few weeks on a changed diet. The effect tends to increase very slowly with time thereafter and it is most pronounced when comparison is made between populations habitually subsisting on different diets. 9. It is not known how the dietary fat intake exerts its controlling influence on the blood lipids of man but the mechanisms must be complex.

Inégalités de santé

“…Par ailleurs, certains paramètres biologiques mesurables inclus dans ces études, comme la cholestérolémie ou la pression artérielle, apparaissent aussi variables, et associés à l'incidence des cardiopathies ischémiques et à la mortalité. C'est Ancel Keys qui, croyant en la prévention diététique de l'athérosclérose (Keys et al, 1955), relance l'épidémiologie géographique, par une série d'études pilotes menées dans différents pays, qui culmine avec « l'étude des 7 pays » initiée en 1957 (Keys, 1980). Cette dernière étude, à la fois transculturelle et prospective, conforte l'hypothèse lipidique au fur et à mesure de la publication des résultats.…”

A short history of saturated fat: the making and unmaking of a scientific consensus

“…Keys based his idea on a handful of small feeding experiments conducted on humans together with some animal data suggesting that high blood cholesterol caused fatty deposits of the type thought to clog arteries and cause heart attacks [2]. Keys had further observed, on travels through post-War Europe, that less wealthy populations in Sardinia, Naples, and Spain, appeared to suffer lower rates of heat attacks while consuming diets low in saturated fat-rich foods, such as meat and dairy [3][4][5]. Keys postulated that saturated fat and cholesterol caused heart disease -his diet-heart hypothesis -whose claims he asserted in no fewer than 20 papers in 1957 and 1958 [2].…”

The Role of Structure and Biophysical Properties in the Pleiotropic Effects of Statins

“…For over a century, cholesterol has been of great interest in science and medicine, from the initial discovery of cholesterine more than 200 years ago [44], its implication in atheromatous plaques in Virchow's Triad [45,46], to the modern use of statins. In addition, adoption of the "lipid hypothesis" of atherogenesis was pivotal in the current understanding of how cholesterol and hypercholesterolaemia relate to coronary artery disease and myocardial infarction [47][48][49][50][51][52][53][54]. This began concurrently during the 1950s' discovery of the clinically relevant relationship between cholesterol and atherogenesis.…”