Aims/hypothesis: We examined the acute postprandial effects of meals containing unsaturated fatty acids on flow-mediated dilation (FMD) of the brachial artery and triacylglycerols in individuals with type 2 diabetes. We hypothesised that consumption of omega-3 fatty acids would enhance vascular function. Saturated fat reduces FMD for several hours, but there is inconsistent evidence about whether foods containing unsaturated fats impair FMD acutely. Little is known about the acute effects of omega-3 fatty acids on vascular reactivity.
Methods: We measured FMD before and 4 h after 3 test meals (50 g fat, 2,615 kJ) in 18 healthy adults with type 2 diabetes. The monounsaturated fatty acids (MUFA) meal contained 50 g fat from high oleic safflower and canola oils. Two additional meals were prepared by replacing 7% to 8% of MUFA with docosahexaenoic acid and eicosapentaenoic acid from sardine oil or alpha-linolenic acid from canola oil.
Results: In the sample as a whole, FMD was increased 17% at 4 h vs. the fasting baseline. After the MUFA meal, subjects with the largest increases in triacylglycerols had the largest FMD decreases. The opposite pattern was observed after meals containing docosahexaenoic acid and eicosapentaenoic acid or alpha-linolenic acid. In subjects with high fasting triacylglycerols, meals containing 3 to 5 g of omega-3 fatty acids increased FMD by 50% to 80% and MUFA alone had no significant effects on FMD.
Conclusions/interpretation: Endothelium-dependent vasodilation was not impaired 4 h after meals containing predominantly unsaturated fatty acids. The fatty acid composition of the meal and the metabolic status of the individual determine the vascular effects of a high-fat meal.