This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition, Subject name: Medicine
Prophylaxis of is essential to prevent which vitamin deficiency in patients taking isoniazid? 
Select and explain. 
A. B1, B. B2, C. B3, D. B6
D: B6
Answer: D: B6 
Explanation: Ans. is 'd' i.e., B6 * Isoniazid reacts with pyridoxal to form a hydrazone, and thus inhibits gneration of pyridoxal phosphate.* Isoniazid also combines with pyridoxal phosphate to interfere with its coenzyme function. Due to formation of hydrazones, the renal excretion of pyridoxine compounds is increased.* Thus, isoniazid therapy produces a pyridoxine deficiency state.