Acetyl l Carnitine Ameliorates Metabolic and Endocrine Alterations in Women with PCOS: A Double Blind Randomized Clinical Trial Advances in Therapy Springer Nature Link Targeting Skeletal Muscle Dysfunction With L Carnitine for the Treatment of Patients With Chronic Obstructive Pulmonary Disease In Vivo 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. Carnitine Deficiency: What Is It, Causes, Symptoms, and More Osmosis