Review Unresolved Problems in the Diet-Heart Issue

An enigma for the 1980s is the continuing diet-heart controversy. Over 60 years ago, the cholesterol-fed rabbit model of atherosclerosis was discovered, and coronary atherosclerosis was linked to the clinical syndrome of myocar-dial infarction. Over 30 years ago, the role of dietary fat in the etiology of atherosclerotic disease was suggested, and epidemiologic evidence linking diet to atherosclerotic disease began to accumulate. The number of scientific papers on diet and atherosclerosis is now enormous. On the one hand, believers assemble these reports into an argument for dietary cholesterol and saturated fat being major causative agents for the high levels of atheroscle-rosis in the technically developed countries. On the other hand, skeptics contend that inconsis-tencies, gaps, and paradoxes in the evidence do not permit one to infer a causative relationship between these dietary components and athero-sclerosis. When conservative interpretations of the diet-heart issue1 are contrasted with recommendations such as those of the American Heart Association,2 it is no wonder that the public is confused. Why is this issue so difficult to resolve? In this review, we will examine selected aspects of the diet-heart relationship that may be responsible for some of the gaps in the evidence linking diet to atherosclerotic disease. The first of these, th