Cholesterol and coronary disease--outstanding questions.

The role of raised blood cholesterol in causing coronary atheroma is established, and a high dietary intake of saturated fat is a leading cause of coronary disease. Reduction of hypercholesterolemia in middle-aged males reduces CHD incidence, mostly nonfatal myocardial infarction. But there are many unresolved questions that should lead to a selective and moderate approach to the management of hypercholesterolemia. These include lack of the exact knowledge of how raised cholesterol leads to atheroma, equivocal evidence of whether reduction of hypercholesterolemia causes regression of atheroma, uncertainty about how far down cholesterol levels can safely be reduced and whether the cost-benefit always justifies action, the fact that reduction of hypercholesterolemia does not reduce total mortality and may increase noncardiac mortality, and insufficient evidence as to whether the same policies should be adopted for women, the elderly, and adolescents as for middle-aged men.