COMPARISON OF 3 FATTY MEALS IN HEALTHY NORMOLIPIDEMIC MEN - HIGH POSTPRANDIAL RETINYL ESTER RESPONSE TO SOYBEAN OIL

Background Oral fat tolerance tests (FTTs) have been widely used as a tool to investigate post-prandial lipaemia. However, there is no conse nsus regarding the type and amount of fat used in the tests. Methods W e compared three commonly used FTTs, each containing 63 g of fat: a mi xed meal, a liquid cream meal and a liquid soybean oil meal. The study group consisted of 10 healthy normolipidaemic men. We measured trigly cerides (TGs), retinyl esters (REs), apolipoprotein E (apoE), apolipop rotein B-48 (apoB-48) and apolipoprotein B-100 (apoB-100) in plasma an d in triglyceride-rich lipoprotein (TRL) fractions separated by densit y-gradient ultracentrifugation at baseline and 3, 4, 6, and 8 h after the FTTs. Results We observed similar TGs, apoE, apoB-48 and apoB-100 responses after all three FTTs, despite the different fatty acid compo sition of the meals. In contrast, the commonly used marker for exogeno us particles, RE, differed clearly when polyunsaturated (soybean oil) and saturated fat (cream or mixed meal) were used. The RE response in plasma (P<0.005, repeated measures ANOVA), in chylomicrons (P<0.013) a nd in very low-density lipoprotein (VLDL) 1 (P<0.017), as well as the RE area under the incremental curve in plasma and chylomicron fraction s, were markedly increased after the soybean oil meal compared with th e mixed meal and cream meal tests. The peak of RE response occurred pa rallel to the responses of other markers (i.e. TG or apoB-48) of post- prandial TRL during soybean oil meal. In contrast, RE peak concentrati on was delayed after saturated fat-containing meals. After soybean oil , FTT plasma cholesterol concentration was lower and the chylomicron c holesterol concentration was higher compared with mixed or cream meals , but no differences were detected in post-prandial high-density lipop rotein (HDL)cholesterol concentration. Conclusion When the amount of f at is similar, post-prandial responses of TG, apoE, apoB-48, apoB-100 and HDL-cholesterol were comparable after different FTTs.