Chronic fish oil intervention had been shown to have a positive impact on endothelial function. Although high fat meals have often been associated with a loss of postprandial vascular reactivity, studies examining the effects of fish oil fatty acids on vascular function in the postprandial phase are limited. Our aim was to examine the impact of the addition of fish oil fatty acids to a standard test meal on postprandial vascular reactivity.

Twenty-five men received in random order either a placebo oil meal (40 g of mixed fat, fatty acid profile representative of the UK diet) or a fish oil meal (31 g mixed fat and 9 g fish oil) on 2 occasions. Vascular reactivity was measured at baseline (0 h) and 4 h after the meal by laser Doppler iontophoresis and blood samples taken for the measurement of plasma lipids, total nitrite, glucose and insulin. Endothelial nitric oxide synthase (eNOS) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase mRNA gene expression was determined in endothelial cells after incubation with triacylglycerol-rich lipoproteins (TRLs) isolated from the 4 h plasma samples.

Compared with baseline, sodium nitroprusside (endothelial independent vasodilator) induced reactivity (P=0.024) and plasma nitrite levels (P=0.001) were increased after the fish oil meal. In endothelial cells, postprandial TRLs isolated after the fish oil meal increased eNOS and decreased NADPH oxidase gene expression compared with placebo oil meal TRLs (P
In conclusion, meal fatty acids appear to be an important determinant of vascular reactivity, with fish oils significantly improving postprandial endothelial independent vasodilation.