Carnitine is best described as which?

• A. A trimethyl amino acid similar in structure to choline, it is required as a cofactor for transformation of free long-chain fatty acids into acylcarnitines and transport into the mitochondria.
• B. An essential mineral involved in bone formation.
• C. A carbohydrate used for energy.
• D. A water-soluble vitamin used in glycolysis.

Answer: (A)

Carnitine’s job is to shuttle long-chain fatty acids into the mitochondria so they can be oxidized for energy. It’s a trimethyl amino acid derivative, structurally similar to choline, which helps it act as a carrier in the fatty acid transport system. In the mitochondria, long-chain fatty acyl-CoA is converted to acylcarnitine by CPT I, allowing entry into the matrix, where CPT II reconverts it to acyl-CoA for beta-oxidation. Because this transport step is essential for fat-derived energy, the description that carnitine is required as a cofactor for forming acylcarnitines and moving them into the mitochondria fits best. It’s not a mineral involved in bone, a carbohydrate, or a vitamin used in glycolysis.