Acute ingestion of different dietary fatty acid species modulates postprandial lipid responses in New Zealand white rabbits

Although several invetigations have linked the degree of fatty acid saturat ion to plasma lipid responses in the postprandial state, further evaluation is necessary. In this study, we compared the effect of saturated (SFA), mo nounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids on postprandia l lipid metabolism using complementary in vivo and in vitro approaches. Fat (10 g) cholesterol (0.5 g) test meals that provided either lard (SFA), oli ve oil (MUFA), or sunflower oil (PUFA) were ingested by chow-fed New Zealan d white rabbits (n = 8). In addition, hepatic uptake of triglyceride-choles terol-rich lipoproteins (TCRL) isolated from rabbits chronically ingesting SFA, MUFA, or PUFA diets was measured using freshly isolated chow-fed rabbi t hepatocytes. Whatever dietary fatty acids ingested, postprandial triglyce ridemia and occurrence of radiolabelled dietary lipids in plasma were not m arkedly different. Conversely, SFA induced higher postprandial cholesterole mia and phospholipemia than MUFA (P < 0.05) whereas PUFA prevented postpran dial cholesterol increase. TCRL disappearance from cultured liver cell medi a was delayed with SFA-rich TCRL and faster with PUFA whereas MUFA-rich TCR L showed an intermediate figure. From these data, we conclude that SFA, MUF A, and PUFA elicited different postprandial plasma and lipoprotein lipid re sponses. The fatty acid composition of TCRL had a major impact on their sub sequent metabolism, especially uptake by cultured hepatocytes. The SFA-indu ced hypercholesterolemia could be related to an altered hepatic uptake wher eas a faster clearance and hepatic uptake could explain the cholesterol-low ering effect of PUFA in rabbits. MUFA, like PUFA, accelerate uptake by hepa tocytes but favor cholesterol ester enrichment of TCRL. (C) Elsevier Scienc e Die. 1999. All rights reserved.