Transformation of free long-chain fatty acids into acylcarnitines requires which nutrient?

• A. Carnitine
• B. Choline
• C. Arginine
• D. Glutamine

Answer: (A)

Carnitine is required to form acylcarnitines and transport long-chain fatty acids into the mitochondria for beta-oxidation. In cytosol, fatty acids are activated to fatty acyl-CoA, then CPT I transfers the acyl group to carnitine to make fatty acylcarnitine. This acylcarnitine is shuttled into the mitochondrial matrix by a specific transporter, where CPT II transfers the acyl back to CoA for oxidation. Short- and medium-chain fatty acids can enter mitochondria without this shuttle, but long-chain fatty acids rely on carnitine. The other nutrients listed do not participate in this transport process.