Carnitine has a central role in fat metabolism. During the overnight fasted state and in exercise performed at low to moderate intensity, long chain fatty acids serve as the primary energy source for Functional differences between l and d carnitine in metabolic regulation evaluated using a low carnitine Nile tilapia model British Journal of Nutrition Cambridge Core L Carnitine Vitamin Supplement for Energy and Metabolism Boost Carnitine transport and fatty acid oxidation ScienceDirect Translating the basic knowledge of mitochondrial functions to metabolic therapy: role of L carnitine ScienceDirect Targeting Skeletal Muscle Dysfunction With L Carnitine for the Treatment of Patients With Chronic Obstructive Pulmonary Disease In Vivo