<prompt> Which of the following vitamin deficiency causes pellagra?ThiamineAscorbic acidNicotinic acidCyanocobalamine  <response>: Ans. c Nicotinic acid. Ref. Harrison, Medicine, 14th ed., 463NIACIN Function: CoA enzyme in redox reactions. 1 mg of niacin is formed from 60 mg of tryptophan. Deficiency: Pellagra diarrhea, dermatitis, dementia and death if untreated. Hartnup disease, malignant carcinoid syndrome and INH therapy may also cause niacin deficiency. 