Solaray No Flush Niacin is a great daily source of niacin. Vitamin B3, also called niacin, is one of eight water-soluble B vitamins. All B vitamins help the body to convert carbohydrates into glucose (sugar), which is burned to produce energy. These B vitamins, often referred to as B complex vitamins, are essential in the breakdown of fats and protein. B complex vitamins also play an important role in maintaining muscle tone along the digestive tract and promoting the health of the nervous system, skin, hair, eyes, mouth, and liver.