Clinical Briefs:Dietary Strategies for CHD Prevention

With Comments from John La Puma, MD, FACP

Source: Hu FB, Willett WC. Optimal diets for prevention of coronary heart disease. JAMA 2002;288:2569-2578.

A review was undertaken of the best metabolic, epidemiologic, and clinical trial evidence regarding diet and coronary heart disease (CHD) prevention. Controlled trials with clinical endpoints were sought; as few exist, substantial weight was given to large prospective cohort studies that reported disease outcomes and metabolic studies with established intermediate endpoints.

Analyzing MEDLINE through May 2002 for epidemiologic and clinical investigations of CHD and major dietary factors (fat, cholesterol, omega-3 fatty acids, trans-fatty acids, carbohydrates, glycemic index, fiber, folate, specific foods, and dietary patterns) yielded 147 original investigations and reviews of metabolic studies, epidemiologic studies, and dietary intervention trials of diet and CHD. Data were examined for relevance and quality and extracted by one of the authors.

Compelling evidence from metabolic studies, prospective cohort studies, and clinical trials in the past several decades indicates that at least three dietary strategies are effective in preventing CHD: substitution of nonhydrogenated unsaturated fats for saturated and trans-fats; increased consumption of omega-3 fatty acids from fish, fish oil supplements, or plant sources; and consumption of a diet high in fruits, vegetables, nuts, and whole grains and low in refined grain products.

However, simply lowering the percentage of energy from total fat in the diet is unlikely to improve lipid profile or reduce CHD incidence. Many issues remain unsettled, including the optimal amounts of monounsaturated and polyunsaturated fats, the optimal balance between omega-3 and omega-6 polyunsaturated fats, the amount and sources of protein, and the effects of individual phytochemicals, antioxidant vitamins, and minerals.

Substantial evidence indicates that diets using nonhydrogenated unsaturated fats as the predominant form of dietary fat, whole grains as the main form of carbohydrates, an abundance of fruits and vegetables, and adequate omega-3 fatty acids can offer significant protection against CHD. Such diets, together with regular physical activity, avoidance of smoking, and maintenance of a healthy body weight, may prevent the majority of cardiovascular disease in Western populations.

Comment

More than any other question, patients ask me, "Is it OK if I eat (fish) (butter) (fast food)?" Of course, I love this—I’d much rather try to clear up the confusion in the office, by e-mail, or on the phone, then have to deal with the stroke, heart attack, hypertension, diabetes, or cancer that is down the road.

Drs. Hu and Willett have championed the traditional Mediterranean diet, finding that it is not total fat that matters in heart disease, but the kind of fat. This review allows them to show us the money—with extensive and authoritative references.

They find that a variety of diets can prevent heart disease, as long as they include foods with omega-3 fatty acids (fish, flax, walnuts, and purslane); low glycemic loads and lots of soluble fiber (barley, oats, and beans); folic acid (grains, cereals, and leafy greens); nuts (especially walnuts and almonds); small amounts of alcohol (< 5 g/d); and more fruits and vegetables (especially leafy greens, and specifically not potatoes).

The authors acknowledge the anatomical success of cardiologist Dean Ornish’s very low-fat diet, exercise, stress management, and yoga program, which significantly reduced progression of atherosclerosis, but find it "unnecessarily rigid and difficult for most people to follow."

They show why the major source of protein should come from nuts, soybeans, legumes, poultry, and fish; the major source of fats should come from the same, and from vegetables, olives, and canola; and the major source of carbohydrates should come from whole, unrefined grains, fruits, and vegetables. Trans fats should be minimized or eliminated, as should saturated fats.

Recommendation

Patients who have coronary disease and want to halt its progression should eat this way. To help them maintain motivation (and a healthy weight) over the long term, they need one-on-one accountability, effective self-monitoring, and 150-300 minutes of exercise weekly. Recommend a physician or dietitian who specializes in this work if you cannot give it your time.