Figure 2. In the mitochondrial matrix, butyrate undergoes ß-oxidation and produces acetyl-coenzyme A. Because of the excess of acetyl-coenzyme A produced by butyrate and the limited capacity of the Krebs cycle, part of the acetyl-coenzyme A is then redirected to the synthesis of fatty acids in the cytosol. The acetyl-coenzyme A used in fatty acid production is transported from the mitochondria to the cytosol by a complicated transfer mechanism involving carnitine and carnitine acyl-carnitine translocase (CACT). This mechanism is also important to maintain a normal level of intramitochondrial free CoA that is, therefore, available for further metabolic reactions (A). In case of carnitine deficiency, there is a complete acylation of the mitochondrial CoA pool, a very risky situation that results in the breakdown of mitochondrial oxidative metabolism (B).