does vitamin b complex contain niacin
View full size image. Vitamin B3, also called niacin, is one of the eight B-complex water-soluble vitamins. Niacin has a wide range of uses in the body, helping functions in the digestive system, skin and nervous system.iew full size image. Vitamin B3, also called niacin, is one of the eight B-complex water-soluble vitamins. Niacin has a wide range of uses in the body, helping functions in the digestive system, skin and nervous system.