Absorption of vitamin B12 requires intrinsic factor produced by which gastric cell type?

• A. Parietal Cells
• B. Chief Cells
• C. Mucous Cells
• D. Enteroendocrine Cells

Answer: (A)

Intrinsic factor needed for vitamin B12 absorption is produced by gastric parietal cells. These cells secrete both hydrochloric acid and intrinsic factor. The B12 you ingest binds to intrinsic factor in the stomach, forming a complex that resists digestion. This complex travels to the terminal ileum, where it binds to specific receptors on enterocytes (cubilin) and is then absorbed. If intrinsic factor isn’t available, B12 absorption drops dramatically, leading to deficiency. Other gastric cell types don’t produce intrinsic factor: chief cells release pepsinogen, mucous cells secrete mucus, and enteroendocrine cells release various hormones.