Carnitine transport and fatty acid oxidation ScienceDirect Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications L carnitine is primarily synthesized in the liver from the amino acids lysine and methionine through a series of four enzymatic reactions, with the liver and kidneys converting the precursor butyrobetaine into active Understanding the Role of Carnitine in TPN and IDPN Therapy Comprehensive review of the expanding roles of the carnitine pool in metabolic physiology: beyond fatty acid oxidation Journal of Translational Medicine Springer Nature Link