INFLUENCE OF DIETS RICH IN SATURATED AND OMEGA-6 POLYUNSATURATED FATTY-ACIDS ON THE POSTPRANDIAL RESPONSES OF APOLIPOPROTEINS B-48,B-1OO,E,AND LIPIDS IN TRIGLYCERIDE-RICH LIPOPROTEINS

The effects of diets rich in saturated fatty acids (SFA) (total polyun saturated fatty acids [PUFA] [g]/total SFA [g][P/S ratio], 0.2) or ome ga-6 PUFA (P/S ratio, 1.3) on the postprandial response of triglycerid e-rich lipoproteins (TRL) was determined in normolipidemic young men. After 15 and 29 days of diet intervention, the postabsorptive concentr ations of apolipoprotein (ape) B-48 and apoB-100 were higher in the SF A group than in the PUFA group, but the absolute increase in apoB-48 w as similar 3 hours after a challenge meal containing one third of dail y energy and returned to postabsorptive values at 6 hours; this respon se was closely coupled to that of TRL triglycerides. In both groups, t he 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 post absorptive values at 6 hours only in those fed the PUFA diet; in the S FA group, apoB-100 remained high at 6 hours and fell below postabsorpt ive values only 9 hours after the meal. This apoB-100 response was aff ected primarily by the fatty acid composition of the diet and not by t hat of the challenge meal. The postprandial response of apoB-100 was c losely coupled to that of cholesterol and apoE. These observations sug gest that in healthy young men, neither the fatty acid composition of the diet nor that of the challenge meal affects the clearance of chylo micron remnants after a fat-containing meal. By contrast, the postpran dial accumulation of hepatogenous TRL is prolonged in individuals fed a diet rich in SFA.