Metabolism: The carnitine shuttle and fatty acid metabolism (practice) Khan Academy Short Note On Carnitine Shuttle: Fatty acids are oxidized in mitochondria, and synthesized in the cytoplasm. Long chain fatty acids must form an active intermediate, fatty acyl CoA, before being oxidized inside mitochondria. Catherine Medium chain fatty acid oxidation is independent of l carnitine in liver and kidney but not in heart and skeletal muscle American Journal of Physiology Gastrointestinal and Liver Physiology American Physiological Society Carnitine: Genetic Variants Affecting Mitochondrial Energy and Health