L Carnitine is an amino acid (a building block for proteins) that is naturally produced in the body. The body can actually produce this substance out of the amino acids lysine and methionine. The body can convert it to other amino acids called acetyl-L-carnitine and propionyl-L-carnitine. L carnitine helps the body produce energy. It is important for heart and brain function, muscle movement, and many other body processes. This amino acid's main role in the body has to do with mitochondrial function and energy production. In cells, it helps transport fatty acids into the mitochondria, where they can be burned for energy. Acetyl-L-carnitine (ALCAR) is a derivative of the amino acid L carnitine. It is produced naturally in the brain, liver, and kidneys and is known to facilitate the uptake of acetyl CoA into the mitochondria during fatty acid oxidation, enhance acetylcholine production, and stimulate protein and membrane phospholipid synthesis.