L Carnitine Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe Early research into L carnitine was often cited as underwhelming, showing negligible changes in muscle carnitine content and fat loss outcomes. However, these findings may have been limited by a short study window Role of L carnitine in female infertility Reproductive Biology and Endocrinology Springer Nature Link L Carnitine Trimethylamine N Oxide From Gut Microbiota in Chronic Kidney Disease Patients: Focus on Diet Journal of Renal Nutrition