Which vitamin requires gastric intrinsic factor secreted by parietal cells in the stomach for its absorption in the terminal ileum?
Answer and explanation
Correct answer: D. Vitamin B12
- Step 1: Vitamin B12 (cobalamin) binds intrinsic factor in the duodenum to form a protease-resistant complex. Step 2. Specific mucosal receptors in the terminal ileum recognize this complex, enabling receptor-mediated endocytosis. Answer: Vitamin B12. Why not the others: Folic acid is absorbed in the proximal jejunum without intrinsic factor; B6 and riboflavin do not require intrinsic factor.
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