Niacin is a water soluble b vitamin naturally found in lean meats fish peanuts mushrooms brown rice and brewers yeast functions of niacin niacin contributes to normal energy yielding metabolism niacin contributes to normal functioning of the nervous system niacin contributes to normal psychological function niacin contributes to the maintenance of normal mucus membranes niacin contributes to the maintenance of normal skin niacin contributes to the reduction of tiredness and fatigue niac