What is the metabolic role of choline?

• A. A cofactor in amino acid synthesis
• B. Structural component of cell membranes only
• C. Acts as a direct antioxidant
• D. Required for lipid transport and metabolism

Answer: (D)

Choline’s metabolic role centers on lipid transport and metabolism because it is converted into phosphatidylcholine, a major phospholipid of cell membranes that is essential for packaging and exporting triglycerides as very-low-density lipoproteins (VLDL) from the liver. Without enough phosphatidylcholine, VLDL synthesis is impaired, causing triglycerides to accumulate in the liver and leading to fatty liver. Choline also serves as a methyl donor via betaine, and it is a precursor to acetylcholine, but the lipid transport function is the primary reason it’s needed for lipid metabolism. The other options don’t fit as well: choline isn’t a cofactor for amino acid synthesis, it isn’t a direct antioxidant, and its role isn’t limited to a structural component of membranes.