[Comparison of the effect of linolenic acid and eicosapentaenoic acid on prostaglandin biosynthesis and thrombocyte function in humans].

Platelet aggregation, bleeding time, prostaglandin biosynthesis and plasma cholesterol fatty acids were investigated in 12 healthy females (25-32 years), who were given different amounts of linolenic acid (0%, 4%, 8%, 12%, 16% of total energy intake) or eicosapentaenoic acid (1.7%) with formula diets for 2 weeks each. Linolenic and eicosapentaenoic acids prolonged the bleeding time and inhibited platelet aggregation and prostaglandin biosynthesis. These effects became apparent after a linolenic acid intake of 12% of the energy intake. A decrease in PGE in 24 h urine was observed after intake of linolenic acid amounting to 8% of energy intake. Eicosapentaenoic acid influenced all parameters measured ten times more than linolenic acid. Linolenic acid intake had no effect on the ratio of linoleic/arachidonic acids in plasma cholesterol esters in contrast to in vitro findings. Thus energy intake comprising 1.7% of eicosapentaenoic acid is sufficient to affect thrombocyte function in man. The concomitant intake of linolenic-type fatty acids inhibits the biosynthesis of prostaglandins E2 and F2 alpha to different degrees.