Which vitamin is responsible for the conversion of tryptophan into niacin?

A Vitamin B6
B Vitamin B12
C Vitamin C
D Vitamin B2 (Riboflavin)
Vitamin B6 (pyridoxine) is necessary for the conversion of tryptophan into niacin, which is an important step in the synthesis of nicotinamide adenine dinucleotide (NAD+).
Guyton and Hall Textbook of Medical Physiology
Vitamins Biochemistry Niacin synthesis Medium MEDICAL Confidence: medium