Lipids and atherosclerosis.

More than 50 years ago the observation was made that the prevalence of atherosclerosis is unusually low among some of the world's populations. Shortly thereafter came the suggestion that this circumstance is due to the low fat content of their diets and the low cholesterol concentration in their blood. Efforts to apply this thinking for the benefit of human health have taken various turns. The first approach was to recommend a low-fat diet. It was thought that the type of fat in the diet was immaterial and that the dietary cholesterol content made no difference either. Later, it was shown that excellent falls in blood cholesterol could be obtained with high-fat diets if most of the fat was polyunsaturated. Dietary cholesterol was found to play a role, but it must be held at exceptionally low levels before its importance becomes evident. Recently, we have become fearful of excessively high intakes of polyunsaturated fats because no population has consumed such a diet over a long period of time and because of suggestive experimental and epidemiological evidence that the incidence of some forms of cancer may be increased. A low-fat, low-cholesterol diet is the preferred prescription for hyperlipidemia.