Carnitine transport and fatty acid oxidation ScienceDirect 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. Amazon.com: Life Extension L Carnitine 500 mg, Energy & Memory Supplement Free Form Amino Acid, Nitric Oxide Support, Healthy Blood Pressure Gluten Free, Non GMO, Vegetarian 30 Capsules (Pack of 2) : The Role of l Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation Acetyl L Carnitine vs L Carnitine: 4 Key Differences Momentous Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications