What are the benefits and side effects of L carnitine (Levocarnitine)? Is L Carnitine safe for athletes at doses up to 6000 mg day? Consensus Role of carnitine in disease Nutrition & Metabolism Springer Nature Link 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