Which of the following vitamin is metabolically produced by the body?: (A) Biotin, (B) Vitamin K, (C) Niacin, (D) Pyridoxine
Answer is C. Essential amino acid tryptophan can be conveed into Niacin (B3) in our body (60 mg tryptophan = 1 mg Niacin). As, it can be synthesised in the body by metabolism, strictly speaking, Niacin is not a Vitamin.