INTERACTIONS BETWEEN DIETARY-FAT, FISH, AND FISH OILS AND THEIR EFFECTS ON PLATELET-FUNCTION IN MEN AT RISK OF CARDIOVASCULAR-DISEASE

Recent studies have suggested that omega 3-fats of marine origin may h ave a protective role in heart disease. This study aimed to compare th e effects of fish or fish oil, in the setting of a high- or low-fat di et, on platelet aggregation and platelet thromboxane in men with incre ased risk of cardiovascular disease. One hundred twenty men who were n onsmokers, 30 to 60 years old, with mildly elevated blood pressure and cholesterol were randomly allocated to one of five high-fat (40% of d aily energy) or two low-fat (30%) groups for 12 weeks. The five high-f at groups took either 6 or 12 fish oil capsules daily; fish; a combina tion of fish and fish oil; or placebo capsules. The two low-fat groups took either fish or placebo capsules. Fish meals provided 1.3 g of ei cosapentaenoic acid daily, equivalent to 6 fish oil capsules, and cont ained an average of 3.65 g/d of omega 3-fatty acids. Multiple regressi on analysis of the combined groups showed that all groups taking omega 3-fatty acids reduced platelet aggregation to both collagen (P<.0001) and platelet-activating factor (PAF) (P<.05) and platelet thromboxane B-2 responses (P<.05) to collagen-induced aggregation. The low-fat di et alone had no effect on PAF-induced platelet aggregation and only a small effect on platelet responses to collagen (P<.05). Platelet aggre gation responses to PAF were reduced more by fish oil than fish in a h igh-fat diet, whereas fish had a greater effect when part of a low-fat rather than a high-fat diet. There was no significant difference in c ollagen-induced platelet aggregation or platelet thromboxane between f ish and fish oils on a high or low fat intake. In conjunction with our previous findings of improvements in lipoproteins, blood pressure, an d heart rate in this population, these results on platelet function su ggest that dietary omega 3-fatty acids incorporated into a low- rather than a high-fat diet have a wider spectrum of more favorable effects on cardiovascular risk factors.