Pathobiological Relationship of Excessive Dietary Intake of Choline L Carnitine: A TMAO Precursor Associated Aggravation in Heart Failure in Sarcopenic Patients Metabolic therapy for cardiovascular diseases with propionyl L carnitine ScienceDirect 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 Primary carnitine deficiency cardiomyopathy International Journal of Cardiology