Effects of linolenic and eicosapentaenoic acids on prostaglandin biosynthesis and platelet function in man

Abstract

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.

Fatty acid composition of the diet: impact on serum lipids and atherosclerosis

“…Regarding the effect of EPA on thrombocyte aggregation (see below) experiments in humans have shown that the equivalent dose of ~-linolenic is approximately tenfold higher [9]. Because of the slow conversion of cz-linolenic acid to EPA and DHA in humans, these very long chain fatty acids may produce effects which are not exhibited by ~-linolenic acid.…”

“…To increase bleeding time, reduce platelet aggregation, and reduce prostaglandin synthesis, approximately the tenfold dose of ~-linolenic acid is needed compared to EPA [8,9]. To increase bleeding time, reduce platelet aggregation, and reduce prostaglandin synthesis, approximately the tenfold dose of ~-linolenic acid is needed compared to EPA [8,9].…”