Postprandial effects of dietary trans fatty acids on apolipoprotein(a) and cholesteryl ester transfer

BACKGROUND: The consumption of trans fatty acids adversely affects fasting plasma lipoprotein concentrations. OBJECTIVE: This study aimed to investigate whether postprandial lipoprotein metabolism is affected by the consumption of trans fatty acids. DESIGN: In a randomized crossover study, 19 healthy men consumed fatty meals that were identical except that 10% of energy was provided as trans 18:1 acids in the trans meal and as oleic acid in the cis meal. RESULTS: The meals induced similar responses in plasma lipids. Cholesteryl ester transfer (CET) was activated after consumption of both meals (P < 0.0001); however, it was 28% higher after the trans meal than after the cis meal (280 +/- 129 compared with 219 +/- 116 nmol cholesteryl ester/mL plasma * 6 h; time x diet interaction: P < 0.0001). Plasma apolipoprotein(a) apo(a)] concentrations remained constant; however, triacylglycerol-rich lipoproteins formed 4 h after ingestion of the trans meal contained a higher concentration of apo(a) than did those formed after ingestion of the cis meal (48.9 +/- 6.6 compared with 39.6 +/- 5.4 U/L; P < 0.02). The change in CET and in the proportion of plasma apo(a) in the triacylglycerol-rich lipoprotein fractions correlated with indexes of alimentary lipemia. CONCLUSIONS: Consumption of meals high in trans fatty acids results in higher CET and postprandial lipoprotein concentrations enriched in apo(a) than does consumption of meals free of trans fatty acids. This study highlights the importance of double-bond configuration in determining postprandial lipoprotein composition.