The effects of saturated fat and n-6 polyunsaturated fat on postprandial lipemia and hemostatic activity.

The effect of different fat loads on postprandial lipemia and hemostatic activity was examined in 10 middle-aged men using 3 different meals. One meal was rich in saturated fatty acids (cream), the other rich in n-6 polyunsaturated fatty acids (sunflower oil) and the third was fat-free containing only carbohydrates. Lipoprotein lipids and hemostatic parameters were measured during fasting and 2, 4, 6 and 8 h after the test meal. In fasting samples, several hemostatic parameters were significantly associated with lipoprotein lipids. Most notable were the strong associations of fibrinolysis parameters tissue plasminogen activator antigen and plasminogen activator inhibitor activity (PAI-1) with total and very low density lipoprotein (VLDL) triglycerides. During lipemia, the associations were approximately similar or slightly weaker than in the fasting state. Both fat loads resulted in similar postprandial lipid responses: VLDL and high density lipoprotein (HDL) triglycerides reached maximum at 4 h after the meal. VLDL cholesterol also increased 4 and 6 h after the fat loads. HDL3 cholesterol declined after the fatty meals but no change was observed in the HDL2 fraction. The fat-free meal gave no significant lipid changes during the time course studied. Factor VII activity (F VII:C) increased 6 and 8 h after the fatty meals, whereas a decrease was observed after the fat-free meal. The changes (+/- S.D.) at 8 h after cream, sunflower oil and fat-free meal were 5.2 +/- 3.3, 3.3 +/- 4.2 and -5.8 +/- 7.9 percentage points, respectively, and the effect of the meal on the changes was statistically significant (F (8,99) = 2.99, P = 0.0048). F VII antigen (F VII:Ag) tended to decline during the day but there was no difference between the meals. Factor VIII activity (F VIII:C) was highest after the polyunsaturated fat meal and lowest after the fat-free meal. PAI-1 declined during the day and the decline tended to be steepest after the fat-free morning meal. The effect of the meal on the changes in lipoprotein lipids and hemostatic factors varied significantly between individuals. In conclusion, postprandial lipemia after a single fatty meal was associated with procoagulatory change in F VII:C but there was no difference between saturated fat and n-6 polyunsaturated fat.