Selective inhibition of OCTN2 is more effective than inhibition of gamma butyrobetaine dioxygenase to decrease the availability of l carnitine and to reduce myocardial infarct size ScienceDirect The Role of L Carnitine in Kidney Disease and Related Metabolic Dysfunctions NKF KDOQI Guidelines History of L carnitine: Implications for renal disease Journal of Renal Nutrition Understanding the Benefits and Uses of Carnitine in Health and Fitness Fitness Health 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.