This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
Gastrectomy produces deficiency of which vitamin 
Select and explain. 
A. Vitamin B6, B. Vitamin B12, C. Vitamin B2, D. Vitamin B1
B: Vitamin B12
Answer: B: Vitamin B12 
Explanation: Gastrectomy produces deficiency of Vit B12.In contrast to other water-soluble vitamins, significant amounts(4-5mg) of vitamin B12are stored in the body. As a result, it may take several years for the clinical symptoms of B12deficiency to develop in individuals who have had a paial or total gastrectomy(who, therefore, become intrinsic factor-deficient, see p. 377) and can no longer absorb the vitamin.1. Reference: Lippincott Textbook of Biochemistry pg no. 376