The bright and the dark sides of L carnitine supplementation: a systematic review Journal of the International Society of Sports Nutrition Springer Nature Link Investigating the effect of permeation enhancers on oral absorption of a BCS IV compound, ombitasvir, utilizing animal models ScienceDirect 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 Revisiting the Role of Carnitine in Heart Disease Through the Lens of the Gut Microbiota