Controlled evaluation of fat intake in the Mediterranean diet: comparative activities of olive oil and corn oil on plasma lipids and platelets in high-risk patients.

Activities of low-fat diets with olive oil or corn oil on lipids and platelets were studied in 23 middle-aged patients with high atherosclerosis risk for 8 wk. The olive oil diet had a polyunsaturated-saturated ratio of 0.33 vs 1.28 for the corn oil diet. Plasma total cholesterol was reduced with corn oil, but high-density lipoprotein cholesterol levels were lower with corn oil and unchanged or raised by olive. Plasma apolipoprotein B levels were equally reduced by both diets; apolipoprotein AI and the apo AI:B ratio rose only with olive oil. Plasma-glucose levels were lowered significantly with olive oil. Changes in platelet function were characterized by a reduced sensitivity to arachidonic acid (particularly with corn oil) and to collagen (particularly with olive). An olive oil diet with a moderate fat intake (about 30% of total calories) leads to favorable plasma lipoprotein and platelet changes.