Effects of a 4-week freshwater fish (trout) diet on platelet aggregation, platelet fatty acids, serum lipids, and coagulation factors.

Eight healthy subjects consumed a diet in which all animal products were replaced by 750 g/day of freshwater trout. Platelet eicosapentaenoic acid (EPA) as a percentage of total platelet fatty acids rose from a prediet level of 0.2 +/- 0.4% to 3.4 +/- 1.6% after 4 weeks on the diet. Platelet arachidonic acid remained unchanged. Platelets became more hyperaggregable to collagen (p less than .025) but became hypoaggregable to arachidonic acid (p less than .05). The Ivy bleeding time became prolonged rising from a mean of 148 seconds before the diet to 168 seconds at 2 weeks and 202 seconds at 4 weeks. Serum lipids, coagulation profiles, and blood pressure remained unchanged. The changes induced by this diet were much less marked than changes induced by marine fish diets and diets supplemented by marine fish oil extracts, despite the fact that an equivalent amount of EPA was consumed and incorporated into platelets. These findings suggest that other substances, in addition to n-3 unsaturated fatty acids, may be responsible for the antithrombotic properties of marine fish.