Abstract 171: Impact of the Mediterranean Diet on Apolipoprotein AI Kinetic in Men with Metabolic Syndrome

Abstract

The impact of the Mediterranean diet (MedDiet) on HDL metabolism has not been extensively studied to date. The objective of the study was to investigate the effect of the MedDiet consumed under controlled isoenergetic feeding conditions on HDL as well as on apolipoprotein (apo) AI kinetic in men with metabolic syndrome (MetS). The diet of 26 men aged between 24 to 62 years with the MetS (NCEP-ATP III) was first standardized to a North American control diet, which was consumed for 5 weeks. MedDiet was then consumed over a subsequent period of 5 weeks. Both diets were consumed under isoenergetic feeding conditions with all foods, including red wine, provided to participants. During the last week of each diet, participants received a single bolus of [5,5,5- 2 H 3 ] L -leucine and fasting blood samples were collected at predetermined time points over a period of 96 hours. Kinetic parameters were derived using multicompartmental modeling of the enrichment data over time. Although no change in plasma HDL-C concentrations was observed, consumption of the MedDiet led to a significant reduction in plasma apoAI concentration and pool size (both P <0.05) compared with the control diet. The MedDiet was also associated with a trend towards a reduction in apoAI production rate (PR, P =0.07) but had no impact on apoAI fractional catabolic rate (FCR, P =0.64). However, only variations in apoAI FCR correlated with diet-induced variations in plasma HDL-C and in apoAI concentrations ( r = -0.50 and r = -0.49 respectively, P <0.02). Based on the individual HDL-C response to MedDiet, responders and non-responders were identified. Participants among whom HDL-C concentrations were increased with MedDiet (mean ΔHDL-C: +9.9 ± 3.2 %) showed significantly greater reductions in apoAI FCR and in apoB and VLDL-TG concentrations (all P <0.04) than those among whom HDL-C levels were reduced after the MedDiet (mean ΔHDL-C: -11.1 ± 4.5 %). Data from this controlled feeding study suggest that the heterogeneous response of HDL-C and apoAI to MedDiet is primarily determined by variations in apoAI FCR, which in turn may be due to concurrent changes in plasma TG concentrations.