Omega-3 polyunsaturated fatty acids alleviate dietary saturated fat-induced postprandial rise in blood lipid levels

Saturated fatty acids (SFA) have been associated with elevated blood lipid levels, although animal studies have demonstrated that dietary SFA raise blood lipid levels only when the diet is deficient in omega-3 polyunsaturated fatty acids (n-3PUFA). Therefore, we investigated the postprandial effects of n-3PUFA supplementation on plasma lipid profile when the background diet was high either in SFA or in omega-6 polyunsaturated fatty acids (n-6PUFA). This was a randomised controlled, cross-over, dietary intervention trial involving 17 healthy females aged 18 to 65 years. Blood was collected after an overnight fast, then subjects consumed a single meal consisting of 3 capsules of n-3PUFA (1.8g), 200mL water and 150g mashed potato mixed with either 38g butter (high SFA) or 32g sunflower oil (high n-6PUFA). Blood samples were then collected at 1, 3, 4 and 6 hours post meal consumption. After 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. Change in plasma triglycerides (measured as area under the curve) was significantly higher when participants consumed n-6PUFA plus n-3PUFA, compared with the SFA plus n-3PUFA meal (P=0.0309). In addition, no significant difference was observed in cholesterol levels. Thus, n-3PUFA supplementation appears to be more effective in controlling post-prandial levels of plasma triglycerides in females, when the background diet contains SFA rather than n-6PUFA.