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
[{'content': 'Which vitamin deficiency causes excretion of xanthurenic acid? \nSelect and explain. \nA. Folic acid, B. Pyridoxine, C. Niacin, D. Vitamin B12', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Pyridoxine deficiency causes the increased excretion of xanthurenic acid Pyridoxal phosphate is required for the synthesis of niacin from tryptophan.Kylureninase is a dependent enzyme.Hence in Pyridoxine deficiency there is a less production of niacin.Moreover, kylurenine is not conveable fuher which is metabolised to xanthurenic acid and excreted through urine. REFERENCE : DM.VASUDEVAN.Textbook of Biochemistry.6th edition Page no 397', 'role': 'assistant'}]