Postprandial lipid and hormone responses to meals of varying fat contents: modulatory role of lipoprotein lipase?

Objective: Substrate and hormone responses to meals of differing fat content were evaluated in normal subjects in order to investigate mechanisms underlying the regulation of postprandial lipoprotein concentration. Design: A randomised cross-over study with three different meals on three occasions. Setting: Free-living subjects associated with Surrey University. Subjects: Ten male volunteers (aged 18-23 years) were recruited. Interventions: Three test meals containing 20, 40 or 80 g fat but identical carbohydrate and protein content were randomly allocated to volunteers. Major outcome measures: Pre- and postprandial blood samples were taken for the analysis of plasma triacylglycerol, non-esterified fatty acids, glucose, immunoreactive insulin and glucose-dependent insulinotrophic polypeptide levels and post-heparin lipoprotein lipase activity measurements. Results: Peak triacylglycerol concentrations and lipoprotein lipase activity measurements were significantly higher following the 80 g than the 20 g fat meal (P = 0.009 and P = 0.049 respectively). Areas under the glucose-dependent insulinotrophic polypeptide time-response concentration curves were significantly higher following the 80 g compared with the 20 g fat meal (P = 0.04), but no differences in insulin response to the meals were seen. The 30-360min decrease in the non-esterified fatty acid concentration was less following the 80g than the 20g meal (P = 0.001) Conclusions: The results suggest that glucose-dependent insulinotrophic polypeptide may mediate increased lipoprotein lipase activity in response to fat-containing meals and may play a role in circulating lipoprotein homeostasis. This mechanism may be overloaded with high fat meals with adverse consequences on circulating triacylglycerol and NEFA concentrations.