What is L Carnitine? L Carnitine is an amino acid, naturally produced in the liver and kidneys. Stored in skeletal muscle, the heart and brain, the main dietary sources of L carnitine are red meat and dairy products. Why use L Carnitine? L Carnitine is a high quality supplement providing 1000mg of L Carnitine per serving. Who can benefit? L Carnitine is an ideal supplement for those looking to increase their L Carnitine intake. To be taken as part of a varied and balanced diet and a healthy lifestyle.