Diet and Coronary Heart Disease

Abstract

Diets low in total fats are widely recommended for the general public for the purpose of prevention of coronary heart disease (CHD). These diets lower the plasma cholesterol and low-density lipoproteins, and they are consumed in many countries where the prevalence of CHD is low. However, low-fat diets have not been widely accepted in the United States and other countries where rates of CHD are high. Although there has been a moderate reduction in fat intake among Americans, this change has not been sufficient to produce a major reduction in plasma cholesterol. For this reason, an alternate approach to lowering the plasma cholesterol by diet is needed.

One approach is to use a diet high in polyunsaturated fatty acids. When polyunsaturates are substituted for saturates in the diet, the result is a fall in cholesterol levels. For this reason, polyunsaturates have been widely advocated. However, polyunsaturates have potential drawbacks. No large populations have ever consumed large amounts of polyunsaturates to prove their safety. Furthermore, these fatty acids have adverse effects in laboratory animals; they suppress the immune system and promote the development of experimental cancer. Thus, many investigators oppose the addition of large amounts of polyunsaturates to the American diet.

A third approach to a cholesterol-lowering diet is to use monounsaturated fatty acids. Monoun-saturates have been consumed in the Mediterranean region for many years, where rates of coronary heart disease and cancers are relatively low. We have carried out metabolic ward studies and have shown that monounsaturates are as effective as both polyunsaturated fatty acids and carbohydrates for lowering plasma total cholesterol and low-density lipoproteins. However, monounsaturates do not lower high-density lipoproteins as do polyunsaturates and carbohydrates. Therefore, monounsaturates appear to be at least as effective as the other two constituents for cholesterol lowering.