L-carnitine can be formed in the animal’s body. The amino acids lysine and methionine act as precursors. The vitamins B6, B12, C, folic acid and niacin and the trace element iron are also necessary as catalysts of the endogenous synthesis of L-carnitine. The highest synthesising capacity is found in the liver. The primary biochemical function of Lcarnitine is to form esters with long-chain activated fatty acids in the cytosol of cells, catalyzed by carnitine palmitoyl transferase type I. These esters have the capacity to penetrate the mitochondial membrane. Within the mitochondrium the esters are cleaved off again from L-carnitine and fatty acids, catalyzed by type II of carnitine palmitoyl transferase. The activated fatty acids released inside the mitochondrium can be utilised for the production of energy via ß-oxidation. ATP is formed as the energetically utilisable end product (see Figure 2).