Which ONE of the following is not a cause of vitamin B12 deficiency?

The answer is D. Vitamin B12 complexed with intrinsic factor (C) is absorbed in the terminal ileum, disease or resection (E) of which will cause failure of absorption.

Dietary deficiency can occur (B). Blind-loop syndrome (A) occurs when bacteria in a loop of bowel proximal to the terminal ileum take up the B12IF complex before it reaches its absorption site.