INFLUENCE OF DIETARY FISH ON PLATELET FUNCTION AND THROMBOXANE FORMATION

Many studies have been performed with respect to the effects of fish (products) on the possible prevention of ischemic cardiovascular disease in man. Most of the trials, however, were poorly designed without a proper control group, and their results are equivocal. We, therefore, performed a well- controlled intervention trial to investigate the effect of a reasonable amount of dietary fish on certain risk indicators of arterial thrombogenesis. In Tromstf, Maastricht and Zeist, healthy male volunteers were given a dietary supplement consisting of 135 g of canned mackerel (n=40) or meat paste (control, n=42) per day for a period of 6 weeks. Compliance was monitored on the basis of the urinary excretion of lithium, added to the supplements. Average compliance was about80% and decreased slightly with time. Bleeding time was significantly prolonged and platelet number decreased in the mackerel group.Platelet aggregation inPRP induced by thrombin decreased only at a low dose.Collagen-induced platelet aggregation in PRP decreased significantly. This was associated with a 50% reduction of the collagen-induced TxB2 formation in PRP(P < 0.001). TxB3 synthesis increased significantly in the mackerel group from 0.9 to 7.8% of the TxB2 production (GC/MS). Collagen- induced platelet aggregation and ATP release in whole blood were measured with the Chronolog whole blood lumiaggregometer (Maastricht only). In the same samples TxB2 formtion was measured (RIA) and although a significant reduction was seen in the mackerel group, platelet functionswere not significantly altered. However, platelet release (but not aggregation) was significantly related to the compliance and a decreasing effect of the mackerel supplement was observed in those 50% of the volunteers having the highest compliance. This demonstrates the necessity of monitoring compliance by objective means. Acknowledgements: Financial support was obtained from the Dutch Heart Foundation. The International Association of Fish Meal Manufactures (Potters Bar, Herts, England) provided the mackerel.