Objective: To assess the effect of a Mediterranean diet (MedDiet) with and without weight loss (WL) on apolipoprotein B100 (apoB100) metabolism in men with metabolic syndrome.
Approach and results: The diet of 19 men with metabolic syndrome (age, 24-62 years) was first standardized to a North American isoenergetic control diet for 5 weeks, followed by an isoenergetic MedDiet for an additional 5 weeks under full-feeding conditions (MedDiet-WL). Participants next underwent a 20-week supervised WL program under free-living conditions (-10.2 ± 2.9% body weight; P<0.01) and finally consumed the MedDiet (5 weeks) under weight-stabilizing feeding conditions (MedDiet+WL). In vivo kinetic of apoB100 was assessed in the fasted state at the end of the 3 controlled diets using a bolus of D3-leucine. Compared with the control diet, MedDiet-WL reduced low-density lipoprotein (LDL)-apoB100 pool size (-14.2%, P<0.01) primarily through an increase in LDL-apoB100 fractional catabolic rate (+30.4%, P=0.02) and increased LDL particle size (P<0.01) but had no effect on very-LDL (VLDL)-apoB100 pool size or triglyceride concentrations, despite a significant increase in VLDL-apoB100 fractional catabolic rate (+25.6%; P=0.03). MedDiet+WL had no further effect on LDL-apoB100 pool size and fractional catabolic rate but further increased LDL particle size and reduced VLDL-apoB100 pool size versus the control diet primarily through an increase in VLDL-apoB100 fractional catabolic rate (+30.7%; P<0.01).
Conclusions: Consumption of MedDiet increases LDL size and reduces LDL-apoB100 concentrations primarily by increasing the catabolism of LDL even in the absence of WL in men with metabolic syndrome. MedDiet seems to have a trivial effect on VLDL concentrations and kinetics unless accompanied by significant WL.
Clinical trial registration -url: http://www.clinicaltrials.gov. Unique identifier: NCT00988650.
Keywords: apolipoprotein B100; diet, Mediterranean; metabolic syndrome; weight loss.