ACUTE EFFECT OF HIGH-FAT MEALS RICH IN EITHER STEARIC OR MYRISTIC ACID ON HEMOSTATIC FACTORS IN HEALTHY-YOUNG MEN

Suggestions have been made that saturated fatty acids with 12-18 carbo n atoms, stearic acid (18:0) in particular, are prothrombogenic. These suggestions are based mainly on in vitro measurements. In the present study the effect of dietary fats high in stearic or myristic acid (14 :0) on plasma triacylglycerol concentrations and key variables of bloo d aggregation (in vitro and in vivo), coagulation, and fibrinolysis wa s studied over 24 h in 10 healthy young men. For each dietary fat, two identical high-fat test meals were served: one in the morning (0 h) a nd one 8 h later, and blood samples were collected at 0, 2, 4, 6, 8, a nd 24 h. Both fats decreased platelet aggregation compared with fastin g values. Stearic fat resulted in a tendency toward lower activity of plasminogen activator inhibitor 1 (PAI-1) than did myristic fat (P < 0 .08). PAI-1 was also lower 24 h after consumption of either fat than i nitially (P < 0.05). Stearic fat, but not myristic fat, tended to caus e some increase in factor VII coagulant activity and beta-thromboglobu lin after 4 h. In conclusion, an acute prothrombotic effect of fats hi gh in myristic and stearic acid was not confirmed.