L carnitine is effective for both fat loss and athletic performance. However, oral L carnitine has lower bioavailability and can be harmful at high doses, so it should be avoided. Even cardiologists give IV Comprehensive Guide to L Carnitine L Tartrate, Methylcobalamin & Folic Acid Tablet Steris Healthcare Pvt Ltd Mumbai Role of carnitine in disease Nutrition & Metabolism Springer Nature Link L Carnitine helps your body turn fat into usable energy and plays a role in recovery, endurance, and even fertility., Your body does make it, and oral supplements are effective but injectable Levocarnitine (Carnitor): Uses, Side Effects, Dosage & More GoodRx