Eight weeks of fish oil supplementation does not prevent sitting-induced leg endothelial dysfunction.

Prolonged sitting impairs leg endothelial function and this impairment is thought to be mediated by a sustained reduction in blood flow-induced shear stress. However, whether nutritional strategies can be used to prevent sitting-induced leg endothelial dysfunction remains unknown. Herein, we tested the hypothesis that 8 weeks of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation would prevent endothelial dysfunction associated with sitting. Nineteen healthy men were randomly assigned to a placebo group or EPA+DHA group in a double-blind fashion. The EPA+DHA group was administered EPA-rich fish oil, containing 600 mg EPA and 260 mg DHA per day for 8 weeks. The placebo group received matching capsules for the same duration of time. Popliteal artery flow-mediated dilation (FMD) was measured at baseline and before and after a 3-h sitting period. During sitting, blood pressure, popliteal artery diameter, and blood velocity were measured every hour. Throughout the sitting period, popliteal artery blood flow and shear rate were markedly and similarly reduced in both groups ( < 0.05). However, counter to the hypothesis, 3 h of sitting impaired popliteal artery FMD to the same extent in both groups ( < 0.05). In conclusion, daily EPA and DHA supplementation is not effective at preventing the detrimental effects of prolonged sitting on leg endothelial function. We provide evidence that sitting-induced leg endothelial dysfunction in young healthy subjects cannot be remediated by a nutritional strategy known to produce cardiovascular benefits. This could be partially due to the low total dose of EPA and DHA administered.