Collagen Synthesis — MFDS Part 1 MCQ

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ModeratePhysiologyCollagen SynthesisMFDS Part 1

A patient with severe dietary restriction presents with gingival bleeding, perifollicular haemorrhages and delayed healing following a dental extraction. Defective collagen maturation is suspected. Which vitamin is required as a cofactor for the hydroxylation of proline and lysine residues in procollagen?

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Correct answer: B — Vitamin C

Vitamin C is the required cofactor for prolyl and lysyl hydroxylases during procollagen maturation. Hydroxyproline helps stabilise the collagen triple helix, while hydroxylysine contributes to glycosylation and subsequent cross-link formation. Deficiency therefore produces structurally defective collagen, causing scurvy with gingival bleeding, perifollicular haemorrhage and impaired wound healing. Vitamin D primarily regulates calcium and phosphate metabolism. Vitamin A supports epithelial differentiation, vitamin K is needed for gamma-carboxylation of several coagulation and bone proteins, and vitamin E acts mainly as a lipid-phase antioxidant. None substitutes for vitamin C in collagen hydroxylation.

Reference: BMJ Open Ophthalmology, Effects of ascorbic acid on trabecular meshwork gene expression and collagen secretion, 2026. https://bmjophth.bmj.com/content/11/1/e002487