Dietary intervention with oil rich fish reduces platelet-monocyte aggregation in man

Background: Dietary intake of fish rich in omega-3 fatty acids is associated with a reduction in cardiovascular events. The mechanisms for this are uncertain and previous studies investigating effects on platelet function have produced inconsistent results. Platelet-monocyte aggregation is a sensitive marker of platelet activation and may contribute to the initiation and progression of atherothrombosis. This study assessed the effect of dietary intervention with oily fish on platelet-monocyte aggregation in healthy subjects. Methods: Fourteen subjects had their diet supplemented with 500 g of oil-rich fish per week for 4 weeks. A control group of 14 subjects received no dietary intervention over a 4-week period. Platelet-monocyte aggregates were assessed with flow cytometry. Results: Dietary intervention with fish led to an increase in omega-3 fatty acids in plasma phospholipids (14.2 +/- 3.4% versus 5.8 +/- 1.3%, P < 0.001). In contrast to the control group, platelet-monocyte aggregates were reduced by 35% following dietary intervention with oily fish (16.0 +/- 9.0% versus 24.8 +/- 10.9%, P < 0.01), and returned to basal levels 4 weeks after discontinuation of supplementation. There was an inverse correlation between platelet-monocyte aggregation and plasma omega-3 fatty acid concentrations (r = -0.421, P = 0.006). There were no changes in the plasma markers of platelet activation, soluble P-selectin or soluble CD40 ligand. Conclusions: We have demonstrated, for the first time, that dietary intervention with oil-rich fish reduces platelet-monocyte aggregation in man. Our results suggest that reduced platelet activation provides a potential mechanism through which fish oils confer their cardiovascular preventative benefits. (C) 2007 Published by Elsevier Ireland Ltd.