Flow-mediated vasodilation is not impaired when HDL-cholesterol is lowered by substituting carbohydrates for monounsaturated fat
British Journal of Nutrition
Low-fat diets, in which carbohydrates replace some of the fat, decrease serum cholesterol. This decrease is due to decreases in LDL-cholesterol but in part to possibly harmful decreases in HDL-cholesterol. High-oil diets, in which oils rich in monounsaturated fat replace some of the saturated fat, decrease serum cholesterol mainly through LDL-cholesterol. We used these two diets to investigate whether a change in HDL-cholesterol would change flow-mediated vasodilation, a marker of endothelial
... er of endothelial function. We fed thirty-two healthy volunteers two controlled diets in a 2 Â 3´5 weeks' randomised cross-over design to eliminate variation in changes due to differences between subjects. The low-fat diet contained 59´7 % energy (en%) as carbohydrates and 25´7 en% as fat (7´8 en% as monounsaturates); the oil-rich diet contained 37´8 en% as carbohydrates and 44´4 en% as fat (19´3 en% as monounsaturates). Average (SD) serum HDL-cholesterol after the low-fat diet was 0´21 (SD 0´12) mmol/l (8´1 mg/dl) lower than after the oil-rich diet. Serum triacylglycerols were 0´22 (SD 0´28) mmol/l (19´5 mg/dl) higher after the low-fat diet than after the oil-rich diet. Serum LDL and homocysteine concentrations remained stable. Flow-mediated vasodilation was 4´8 (SD 2´9) after the low-fat diet and 4´1 (SD 2´7) after the oil-rich diet (difference 0´7 %; 95 % CI 20´6, 1´9). Thus, although the low-fat diet produced a lower HDL-cholesterol than the high-oil diet, flow-mediated vasodilation, an early marker of cardiovascular disease, was not impaired.