Oral administration of l-carnitine improves the clinical outcome of fertility in patients with IVF treatment.

Age-dependent decline of mitochondrial function has been proposed to be a main cause of decline of embryo quality. Then, L-carnitine plays important roles in reducing the membranous toxicity of free-fatty acids by forming acyl-carnitine and promoting beta-oxidation, preventing cell damage. Recent research revealed that L-carnitine played important roles in vitro in oocyte growth, oocyte maturation and embryo development. However, such beneficial effects of L-carnitine in vivo have yet to be verified. The effect of oral L-carnitine supplementation on embryo quality and implantation potential was examined. A total of 214 patients were included in this study. They all previously received in vitro fertilization-embryo transfer (IVF-ET) and failed to conceive. Then they were administered L-carnitine for 82 days on average and underwent IVF-ET again. There were no significant differences in the total number of retrieved oocytes, and their maturation and fertilization rates between before and after L-carnitine administration. The quality of embryos on Days 3 and 5 after insemination was improved following L-carnitine administration (p<.05) in cycles after L-carnitine administration compared with previous cycles. Healthy neonates were born after IVF-ET following L-carnitine administration. Our data suggested that oral administration of L-carnitine to fertility patients improved the developmental competence of their oocytes after insemination.