DHA-rich fish oil reverses the detrimental effects of saturated fatty acids on postprandial vascular reactivity

Background: Experimental elevation of nonesterified fatty acids (NEFAs) impairs endothelial function, but the effect of NEFA composition is unknown. Objective: The objective was to test the effect of acute elevation of NEFAs enriched with either saturated fatty acids (SFAs) or SFAs with long-chain (LC) n23 (omega-3) PUFAs on vascular function measured via flow-mediated dilatation (FMD), laser Doppler iontophoresis (LDI), and digital volume pulse (DVP). Design: In 59 subjects (30 men and 29 women), repeated oral fat feeding of either palm stearin (SFA) or palm stearin with DHA-rich fish oil (SFA + LC n23 PUFA) was performed on 2 separate occasions with continuous heparin infusion to elevate NEFAs for a duration of 60 to 240 min. Vascular function was measured at baseline and at the end of NEFA elevation; venous blood was collected for measurement of lipids and circulating markers of endothelial function. Results: NEFA elevation during consumption of the SFA-rich drinks was associated with a marked impairment of FMD, whereas consumption of SFAs + LC n23 PUFAs improved FMD response, with am ean (6SEM) difference of 2.06 6 0.29% (P , 0.001). Positive correlations were found with percentage weight of LC n2 3P UFAs in circulating NEFAs and change in FMD response [Spearman’s rho (rs )=0 .460,P , 0.001]. LDI measures increased during both treatments (P 0.026), and there was no change in DVP indexes. Conclusions: The composition of NEFAs can acutely affect FMD. The beneficial effect of LC n23 PUFAs on postprandial vascular function warrants further investigation but may be mediated by nitric oxide‐independent mechanisms. This trial is registered at clinicaltrials.gov as NCT01351324. Am J Clin Nutr doi: 10. 3945/ajcn.110.009233.