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 postheparin 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 30-360 min decrease in the non-esterified fatty acid concentration was less following the 80 g than the 20 g 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.