CARNITOR (levocarnitine) Oral Solution (1 g per 10 mL multidose) 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 JCI l Carnitine in omnivorous diets induces an atherogenic gut microbial pathway in humans Revisiting the Role of Carnitine in Heart Disease Through the Lens of the Gut Microbiota