ddecd425____Norris_Cotton_Cancer_Center_Water_soluble_vitamins_Function
[Nutrient] Niacin (vitamin B3) [Sources] Meat, poultry, fish, whole-grain or enriched breads and cereals, vegetables (especially mushrooms, asparagus, and leafy green vegetables), peanut butter [Function] 
Part of an enzyme needed for energy metabolism; important for nervous system, digestive system, and skin health
Vitamins: Their Functions and Sources | Health Encyclopedia | Norris Cotton Cancer Center
Function