Effects of different dietary cholesterol concentrations on lipoprotein plasma concentrations and on cholesterol efflux from Fu5AH cells

Background: The fatty acid composition of the diet can modulate the effect of dietary cholesterol on plasma lipoproteins, However, HDL composition and its capacity to promote cholesterol efflux can be influenced by the diet. Objective: Modifications in plasma lipids and in the capacity of serum to stimulate the cholesterol efflux induced by a low-fat diet [National Cholesterol Education Program (NCEP) Step I diet], by a monounsaturated fatty acid (MUFA)-rich diet, and by addition of cholesterol to both diets was studied. Design: Fifteen young, healthy men followed 2 NCEP Step I diets (< 30% of fat as energy, with < 10% saturated fat and 14% MUFAs) for 24 d, providing 0.027 or 0.068 mg cholesterol kJ(-1) . d(-1), and 2 oleic acid-enriched diets (38% of energy as fat, with 24% MUFAs) providing the same amount of dietary cholesterol as the NCEP Step I diets. Results: Total cholesterol, LDL cholesterol, apolipoprotein (apo) B, and apo A-I concentrations decreased after the NCEP Step I and MUFA diets compared with the usual diet. HDL cholesterol also decreased after the NCEP Step I diet. Total:HDL cholesterol, apo B, and apo B:apo A-I were lower after the MUFA diets than after the NCEP Step I diets. There were no significant differences between the lipid profiles obtained after the NCEP Step I and MUFA diets were enriched with cholesterol. The capacity of serum to promote cholesterol efflux was significantly higher after the cholesterol-enriched NCEP Step I diet than after the NCEP Step I diet. Conclusions: The MUFA diet induced a better lipid profile than the NCEP Step I diet: however, the increase in the cholesterol content of both diets produced similar plasma lipid changes. The cholesterol in the NCEP Step I diet increased the cholesterol efflux induced by total serum.