Frontiers Dietary supplementation with L carnitine elevates intracellular carnitine levels and affects gene expression of SLC25A20 and COX4I1, as well as non mitochondrial respiration of bovine blood cells during systemic immune challenge 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 Carnitine Metabolite of the month biocrates life sciences gmbh Carnitine: Genetic Variants Affecting Mitochondrial Energy and Health Mitochondrial Disease Cause, Symptoms, Treatments