Epidemiology as a guide to clinical decisions--II. Diet and coronary heart disease.

Should clinicians prescribe fat-controlled diets to prevent coronary heart disease (CHD), and, if so, which patients should be given this advice? In this report, we use a three-step model to explain the hypothesis that dietary fats are a cause of CHD: dietary saturated fat and cholesterol raise serum cholesterol levels (step 1), which are a cause of subclinical coronary atherosclerosis (step 2), and, in turn, clinically manifest CHD (step 3). An evaluation of the scientific evidence for each step leads us to conclude that dietary fats definitely influence the level of serum cholesterol, and that serum cholesterol is probably a cause of atherosclerosis and CHD. To determine the clinical implications, we examined the potential of various foods to keep cholesterol levels lower, as well as the projected magnitude of reduction in CHD risk. The likelihood of benefit varies among patients, ranging from uncertain or trivial (for those with lower serum cholesterol levels, those who are free of other risk factors and the elderly) to substantial (for patients with higher serum cholesterol levels, those who have other risk factors and those who are young). This analysis supports an individualized approach to clinical management; each decision to prescribe a fat-controlled diet should be a judgment that depends on art-the therapeutic philosophy of each clinician and the particular needs of each patient-as well as on science. The implication for public health policies is that they should promote rather than a uniform eating pattern for all Americans, a uniform environment that enhances individual choices. This should include efforts to educate the medical profession and the public, and more comprehensive and informative foodlabeling practices.