Does L Carnitine Work for Fat Loss? A Dietitian Explains L carnitine tartrate supplementation in the fight against infectious disease Hypertension and Insulin Resistance Hypertension Comprehensive review of the expanding roles of the carnitine pool in metabolic physiology: beyond fatty acid oxidation Journal of Translational Medicine Springer Nature Link L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy.