Pyrudube B-carboxylic acid, B-carboxypriridine, miacin, C5 H4 NCOOH, the pellagra-preventing (P-P)factor. It occurs in milk,meat, wheat, liver, kidney, yeast and bread; lack of it in the diet leads to the food deficiency disease, pellagra. It is involved in the maintenance of the integrity of the alimentary mucosa.