Influence of diets rich in saturated and omega-6 polyunsaturated fatty acids on the postprandial responses of apolipoproteins B-48, B-100, E, and lipids in triglyceride-rich lipoproteins.

The effects of diets rich in saturated fatty acids (SFA) (total polyunsaturated fatty acids [PUFA] [g]/total SFA [g][P/S ratio], 0.2) or omega-6 PUFA (P/S ratio, 1.3) on the postprandial response of triglyceride-rich lipoproteins (TRL) was determined in normolipidemic young men. After 15 and 29 days of diet intervention, the postabsorptive concentrations of apolipoprotein (apo) B-48 and apoB-100 were higher in the SFA group than in the PUFA group, but the absolute increase in apoB-48 was similar 3 hours after a challenge meal containing one third of daily energy and returned to postabsorptive values at 6 hours; this response was closely coupled to that of TRL triglycerides. In both groups, the percent increase in TRL apoB-48 and triglycerides was greater after the PUFA meal than after the SFA meal. The concentration of TRL apoB-100 also increased at 3 hours in both diet groups but returned to postabsorptive values at 6 hours only in those fed the PUFA diet; in the SFA group, apoB-100 remained high at 6 hours and fell below postabsorptive values only 9 hours after the meal. This apoB-100 response was affected primarily by the fatty acid composition of the diet and not by that of the challenge meal. The postprandial response of apoB-100 was closely coupled to that of cholesterol and apoE. These observations suggest that in healthy young men, neither the fatty acid composition of the diet nor that of the challenge meal affects the clearance of chylomicron remnants after a fat-containing meal. By contrast, the postprandial accumulation of hepatogenous TRL is prolonged in individuals fed a diet rich in SFA.