Pellagra is caused by deficiency of which vitamin?

• A. A
• B. B1
• C. thiamine
• D. niacin

Answer: (D)

Pellagra results from a deficiency of niacin, also called vitamin B3. Niacin is needed to form the coenzymes NAD and NADP, which are essential for many redox reactions in energy metabolism. When niacin is lacking, tissues with high energy demands can falter, producing the characteristic symptoms: dermatitis, diarrhea, and neuropsychiatric symptoms such as dementia. This deficiency is classically seen in diets based on maize with low bioavailable niacin or low tryptophan, which can be remedied by niacin supplementation. The other vitamins listed cause different deficiency syndromes (for example, vitamin A deficiency affects vision, and vitamin B1 deficiency causes beriberi and Wernicke–Korsakoff), so they do not produce pellagra.