The effect of acute carbohydrate load on the monophasic or biphasic nature of the postprandial lipaemic response to acute fat ingestion in human subjects.Br J Nutr. 1998 Nov; 80(5):411-8.BJ
Previous studies in this laboratory have elicited a monophasic response in postprandial plasma triacylglycerol (TAG) level with fat intakes of 0.5 g fat/kg body weight accompanied by about 17 g carbohydrate as lactose. Recent studies involving the same level of fat with a higher level of carbohydrate, 136 g of which 60 g was sucrose, appeared to elicit a biphasic response. The present study compared these two test meals and showed a significant meal x time interaction for plasma total TAG (P = 0.0228) reflecting a monophasic response with the lower-carbohydrate test meal. The higher-carbohydrate meal induced significantly higher insulin and glucose-dependent insulinotropic polypeptide responses (P = 0.0009 and P = 0.0041 respectively). A significant meal x time interaction was seen for plasma non-esterified fatty acids (P = 0.0437). The biphasic plasma TAG response seen with the high-carbohydrate meal largely reflected the TAG-rich lipoprotein (TRL) or chylomicron fraction, which would tend to suggest a biphasic pattern of absorption. This was borne out by TRL-TAG fatty acid compositions. Both peak in the biphasic response showed active incorporation of the main dietary fatty acids, 18:1n-9, 18:2n-6 and 18:3n-3 into TRL-TAG. These results indicate that under the specific test-meal conditions used in the present study, a biphasic pattern of fat absorption was seen.