Dose responses in platelet fatty acid composition, aggregation and prostanoid metabolism during moderate freshwater fish diet.

The dose responses in platelet fatty acid composition, aggregation and thromboxane production and in plasma prostacyclin level during moderate freshwater fish diet was studied in healthy male students (n = 100). There were four fish diet groups eating 0.9, 1.5, 2.3 or 3.8 fish-containing meals per week for 12 weeks. The meals provided about 0.25, 0.5, 0.6 or 1.1 g n-3 fatty acids per day, respectively. The increase of n-3 at the expense of n-6 fatty acids in total platelet lipids took place already with 1.5 weekly fish meals (0.5 g n-3 fatty acids/d). Most of the observed changes in platelet fatty acids were seen already after 5 weeks. ADP-and collagen-induced platelet aggregation was measured from controls and 1.5 and 3.8 fish meals per week groups. The maximum platelet aggregation values of the group with the highest fish intake were significantly lower than in the controls at the end of dietary period. A tendency towards reduced platelet aggregability was observed also in the group eating 1.5 fish meals per weeks. Thromboxane B2 and 6-keto-PGF1 alpha were determined from controls and two groups with highest fish intake. The highest intake was needed to decrease the thromboxane B2 production of clotted blood and the plasma 6-keto-PGF1 alpha concentration. A positive correlation between ADP-induced aggregation and thromboxane B2 production was found. These results show that platelet characteristics can already be modified with a very moderate freshwater fish intake.