Niacin is a B vitamin that’s made and used by your body to turn food into energy. It helps keep your nervous system, digestive system, and skin healthy.

Niacin is a water-soluble B vitamin found naturally in some foods, added to foods, and sold as a supplement. The two most common forms of niacin in food and supplements are nicotinic acid and nicotinamide. The body can also convert tryptophan an amino acid to nicotinamide.