Lipids, Carbohydrates, and Heart Disease

Abstract

The major cause of heart attack and stroke is atherosclerosis. Because the atherosclerotic lesion contains lipid, and because elevated cholesterol levels are epidemiologically associated with heart attack, the major thrust of dietary research in relation to heart disease has been toward fats in the diet. Decades of research in this area have led to the clear conclusions that (1) an increase in low-density lipoprotein cholesterol (LDL-C) predicts the risk of coronary heart disease (CHD) and stroke; (2) the risk of CHD is inversely related to the circulating level of high-density lipoprotein cholesterol (HDL-C); and that (3) the level of very-low-density lipoprotein cholesterol (VLDL-C) does not directly predict heart-attack risk but that an increase in this cholesterol fraction appears to enhance the risk posed by LDL-C. Additionally, the subclass of lipid known as small dense LDL-C has, over the past decade, been shown to predict pathology related to atherosclerosis. Prospective, randomized studies of the beneficial effect of lowering blood cholesterol levels through the use of a variety of drugs have conclusively shown that reducing the level of LDL-C markedly lowers the risk of CHD morbidity and mortality. A recent study directed at increasing the circulating level of HDL has also shown an improved outcome in CHD,1 and another study aimed at reducing triglycerides and raising the level of HDL in diabetic subjects has also shown improved outcome.2 Clearly, therefore, decreasing LDL-C and increasing HDL-C with or without a concomitant decrease in triglycerides improves cardiovascular outcomes.