Effects of monounsaturated enriched sunflower oil on CHD risk factors including LDL size and copper-induced LDL oxidation

Objective: To compare the effects of a diet high in monounsaturated enriched sunflower oil and a low fat diet on CHD risk factors including in vitro Cu-induced LDL oxidation and LDL size, lipids, lipoproteins, glucose and insulin. Design: A randomized crossover dietary intervention. Setting: Free living individuals. Subjects: Fourteen healthy males 35 to 55 years of age and 14 healthy postmenopausal women 50 to 60 years of age completed the dietary intervention. Two subjects did not complete the study, and their data were not included. Interventions: A low fat, high carbohydrate diet (22% to 25% of energy from total fat, 7% to 8% of energy from monounsaturated fat and 55% to 60% of energy from carbohydrate) was compared to a monounsaturated enriched sunflower oil (MO) diet (40% to 42% of energy from fat, with 26% to 28% from monounsaturated fat and 40% to 45% of energy from carbohydrate) in an isocaloric substitution. Each dietary period was one month. Results: Total cholesterol, LDL cholesterol, triglycerides and glucose were not significantly different between the two diets. HDL cholesterol, HDL3 cholesterol and insulin were significantly higher on the MO diet, mean 7%, 7% and 17% higher respectively. Copper-induced LDL oxidation lag phase was significantly longer (mean 18%) after the MO diet compared to the low fat, high carbohydrate diet. LDL particle size was not significantly different. Conclusions: The significant increase in LDL oxidation lag phase and the significantly higher HDL cholesterol on the MO diet would be expected to be associated with a decrease in CHD risk.