Nicotinamide, or vitamin B3, is a water-soluble vitamin B found naturally in some foods, added to foods, and sold as a supplement. The two most common forms of Vitamin B3 in food and supplements are nicotinic acid and nicotinamide. The body can also convert tryptophan—an amino acid—to nicotinamide. Vitamin B3 is water-soluble so excess amounts the body does not need are excreted in the urine. Vitamin B3 works in the body as a coenzyme, with more than 400 enzymes dependent on it for various reactions. Vitamin B3 helps to convert nutrients into energy, create cholesterol and fats, create and repair DNA, and exert antioxidant effects.