Metabolic syndrome (MetS) is associated with adverse cardiovascular events, and impaired vascular function. In this study we evaluated the effects of omega-3 polyunsaturated fatty acids (PUFAs) supplementation on vascular function, inflammatory and fibrinolytic process in subjects with MetS.

We studied the effect of a 12 weeks oral treatment with 2 g/day of omega-3 PUFAs in 29 (15 male) subjects (mean age 44 ± 12 years) with MetS on three occasions (day0: baseline, day 28 and day 84). The study was carried out on two separate arms (PUFAs and placebo), according to a randomized, placebo-controlled, double-blind, cross-over design. The diagnosis of MetS was based on the guidelines of Adult Treatment Panel III definition. Endothelial function was evaluated by flow-mediated dilation (FMD) of the brachial artery. Carotid-femoral pulse wave velocity (PWV) was measured as an index of aortic stiffness. Serum levels of interleukin-6(IL-6) and plasminogen activator inhibitor-1(PAI-1) were measured by ELISA.

Treatment with PUFAs resulted in a significant improvement from day 0 to 28 and 84 in FMD and PWV (p < 0.001 for all). Nevertheless, treatment with placebo resulted in no significant changes in FMD (p = 0.63) and PWV (p = 0.17). Moreover, PUFAs treatment, compared to placebo, decreased IL-6 levels (p = 0.03) and increased PAI-1 levels (p = 0.03). Finally, treatment with PUFAs resulted in a significant decrease in fasting triglyceride levels from day 0 to 28 and 84 (p < 0.001) and in serum total cholesterol levels (p < 0.001).

In subjects with MetS, treatment with omega-3 PUFAs improved endothelial function and arterial stiffness with a parallel antiinflammatory effect.