Postprandial lipemia following consumption of saturated fat and omega-6PUFA rich diets: interactions with omega-3PUFA

Background: Consumption of foods high in saturated fatty acids (SFA) has been associated with elevated blood lipid levels and consequently with increased risk of chronic diseases. However, studies on animal models have demonstrated that dietary SFA raise blood lipid (cholesterol and triglyceride) levels only when the diet is deficient in omega-3 polyunsaturated fatty acids (omega-3PUFA). Objective: To examine the postprandial effects of omega-3PUFA supplementation on plasma lipid profile when the background diet is high either in SFA or in omega-6 polyunsaturated fatty acids (omega-6PUFA). Design: The study was a randomised controlled, cross-over, dietary intervention trial involving 17 healthy women aged 18 to 65 years. Blood was collected after an overnight fast, then subjects consumed a single meal consisting of 3 capsules of omega-3PUFA (1.8g), 200mL water and 150g mashed potato mixed with either 38g butter (Meal A, high SFA) or 32g sunflower oil (Meal B, high omega-6PUFA). Blood samples were then collected at 1, 3, 4 and 6 hours post meal consumption. Following at least one week washout, the same procedure was repeated, following consumption of the alternate meal. Blood lipid profile (cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides) was measured at each time point. Outcomes: The change in plasma triglycerides (measured as area under the curve) was significantly higher when participants consumed omega-6PUFA plus omega-3PUFA, compared with the SFA plus omega-3PUFA meal (P=0.0309). A trend for higher change in plasma triglycerides in pre-menopausal women was also evident (P=0.0663). No significant difference was observed in plasma total, LDL and HDL-cholesterol. Conclusion: Change in plasma cholesterol was similar when subjects consumed either SFA or omega-6PUFA in association with of omega-3PUFA. However, omega-3PUFA supplementation appears to be more effective in controlling post-prandial levels of plasma triglycerides when the background diet contains SFA rather than omega-6PUFA. Source of funding: PRC in Physical Activity & Nutrition, University of Newcastle, NSW, Australia and CNPq (Coordenação Nacional de Desenvolvimento Científico e Tecnológico), Brazil.