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Although chronic fish oil intervention had been shown to have a positive impact on vascular reactivity, very little is known about their acute effects during the postprandial phase. Our aim was to examine the impact of a fish oil-enriched test meal on postprandial vascular reactivity in healthy younger ( v. older ( ≥ 50 years) men. Vascular reactivity was measured at baseline (0 h), 2 and 4 h after the meal by laser Doppler iontophoresis and blood samples taken at 0 and 4 h for the measurement of plasma lipids, total nitrite, glucose and insulin. Acetylcholine- (ACh, endothelial-dependent vasodilator) and sodium nitroprusside (SNP, endothelial-independent vasodilator)-induced reactivities were greater at 4 h than at baseline or 2 h in the younger men (P P = 0·006) and SNP (P = 0·05) at 4 h in the younger compared with the older males. Postprandial NEFA concentrations were also greater at 4 h in the younger compared with the older men (P = 0·005), with no differences observed for any of the other analytes. Multiple regression analysis revealed age to be the most significant predictor of both ACh and SNP induced reactivity 4 h after the meal. In conclusion, the ingestion of a meal enriched in fish oil fatty acids was shown to improve postprandial vascular reactivity at 4 h in our younger men, with little benefit evident in our older men.

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. The aim of the present study was to examine the impact of the addition of fish oil fatty acids to a standard test meal on postprandial vascular reactivity. A total of 25 men received in a random order either a placebo oil meal (40 g of mixed fat; fatty acid profile representative of the U.K. diet) or a fish oil meal (31 g of mixed fat and 9 g of fish oil) on two occasions. Vascular reactivity was measured at baseline (0 h) and 4 h after the meal by laser Doppler iontophoresis, and blood samples were taken for the measurement of plasma lipids, total nitrite, glucose and insulin. eNOS (endothelial NO synthase) and NADPH oxidase gene expression were determined in endothelial cells after incubation with TRLs (triacylglycerol-rich lipoproteins) isolated from the plasma samples taken at 4 h. Compared with baseline, sodium nitroprusside (an endothelium-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 TRLs isolated following the placebo oil meal (P≤0.03). In conclusion, meal fatty acids appear to be an important determinant of vascular reactivity, with fish oils significantly improving postprandial endothelium-independent vasodilation.