Background: Hyperlipidemia and obesity are associated with metabolic syndrome and increased risk in developing diabetes and cardiovascular disease. Nutritional supplements, e.g. L-carnitine and polyunsaturated fatty acids (PUFAs), exert lipid-lowering effects. Hence, the hypothesis that dietetic intervention reduces plasma lipid levels and metabolic enzymes in overweight hyperlipidemic subjects was tested. Subjects and Methods: In a prospective placebo-controlled double-blind study in 22 moderately hyperlipidemic obese humans consuming low-fat yoghurt enriched with a combination of low-dose PUFAs, polyphenols and L-carnitine (PPC) twice a day for 12 weeks were compared to 20 matching participants ingesting low-fat yoghurt. The effects on plasma lipids and expression of enzymes involved in regulation of fatty acid oxidation in peripheral blood mononuclear cells (PBMCs) and HepG2 cells were evaluated. Results: PPC consumption led to significantly reduced plasma free fatty acid (–29%) and triglyceride (–24%) concentrations (each p < 0.05). PPC application increased significantly peroxisome proliferator-activated receptor α (PPARα) mRNA abundances and those of PPARα target genes (carnitine palmitoyltransferases-1, CPT1A and CPT1B, carnitine acetyltransferase and organic cation transporter 2; each p < 0.05) in PBMCs. In controls, plasma lipid levels and PBMC gene expression did not change. These findings were substantiated by the results of cell culture experiments in HepG2 cells. Conclusion: Supplementation of PPC had marked lipid-lowering effects and PBMC gene expression profiles seemed to reflect nutrition-related metabolic changes.

Increased plasma free fatty acid (FFA) levels are a feature of insulin resistance and type 2 diabetes. The aim of the present study was to assess the effect of L-carnitine supplementation on plasma lipids and the expression of enzymes in peripheral mononucleated cells (PMNC) involved in the regulation of fatty acid and glucose oxidation. L-Carnitine supplementation of 2 g/day resulted in a significant decrease in plasma FFA and in a less pronounced diminution of the plasma triacylglycerols. In addition, a concomitant increase in the relative mRNA abundances of carnitine acyltransferases (5- to 10-fold) and of the carnitine carrier OCTN2 (12-fold) in PMNC of pregnant women was found. The results of the present study provide evidence that L-carnitine supplementation in pregnancy (2 g/day) avoids a striking increase in plasma FFA, which are thought to be the main cause of insulin resistance and consequently gestational diabetes mellitus.