Compounded Carnitine (L) Injection Empower Pharmacy 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 L Carnitine: Benefits, Uses, Side Effects, and More Revisiting the Role of Carnitine in Heart Disease Through the Lens of the Gut Microbiota