Vascular tone is, in part, controlled by a balance of mediators released into the blood stream by endothelial cells. Hypercholesterolemia disrupts this function, resulting in atherosclerosis. Studies in animals have demonstrated that diet can normalize endothelial dysfunction. In humans, a low-fat, low–saturated-fat diet (National Cholesterol Education Program stage 1 [NCEP-1] diet) is recommended to prevent atherosclerosis. Another diet that appears to be related to a lower risk of coronary heart disease is a Mediterranean diet rich in linolenic acid and monounsaturated fat.

Fuentes and associates examined the effects of these “healthy” diets on endothelial function in patients with hypercholesterolemia. Twenty-two men with plasma cholesterol concentrations greater than 200 mg per dL (5 mmol per L) were given a diet high in saturated fat for 28 days, after which they were divided into two groups. Each of these groups was assigned in a random, crossover design to either the Mediterranean diet or the NCEP-1 diet for two 28-day periods. Lipid profiles were measured at the conclusion of each diet intervention. Endothelial function was measured at the same time using postischemic vasodilation techniques and two-dimensional ultrasonography.

There was a significant decrease in the levels of plasma cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B following the NCEP-1 and Mediterranean diets. Endothelium-dependent vasodilation increased with the two low–saturated-fat diets, signifying improved endothelial function.

The authors conclude that correcting endothelial function through a lipid-lowering diet may protect against the progression of atherosclerosis.