Serum enriched with n-3 polyunsaturated fatty acids inhibits procoagulant activity in endothelial cells

Nine healthy male volunteers (mean age 24.3 years, range 21-27 years) ingested 25 ml cod liver oil (CLO) daily for 8 weeks. Blood samples were collected before and after the intervention period. A slight increase in total serum cholesterol (+ 12.2%, P less than 0.01) and high density lipoprotein cholesterol (+ 16.9%, P less than 0.01) were calculated to have a non-significant effect on the high/low density lipoprotein ratio. Polyunsaturated fatty acids in serum were displaced from the n-6 family to the n-3 family, reflected by an eight-fold increase of the eicosapentaenoic (20:5 n-3)/arachidonic (20:4n-6) acid ratio. Human umbilical vein endothelial cells were grown in a medium to which 30% sterile filtered serum, collected before and after CLO supplementation for 72 h, was added. After 2 h exposure to lipopolysaccharides the thromboplastin activity in endothelial cultures incubated with serum enriched with n-3 fatty acids was 43% lower than in cultures containing serum collected before the intervention (1.86 +/- 0.48 10(-3)/10(6) cells vs 3.26 +/- 0.85 10(-3)/10(6) cells). It is suggested that serum prepared from subjects given n-3 fatty acids may support the thromboresistence of endothelial cells.