Pellagra is associated with deficiency of which vitamin?

• A. Biotin
• B. Folic acid
• C. Niacin
• D. Thiamine

Answer: (C)

Pellagra results from a deficiency of niacin, which is vitamin B3. Niacin is a key part of the coenzymes NAD+ and NADP+, essential for many oxidation–reduction reactions in energy metabolism. When niacin intake is too low or its precursor tryptophan is not available, the body's NAD/NADP supplies dwindle, especially affecting skin, gut, and brain. This leads to the classic dermatitis (often in sun-exposed areas), diarrhea, and dementia that characterize pellagra, and can be fatal if untreated. Conditions or factors that raise niacin needs or reduce its production—such as diets heavily based on corn, Hartnup disease, carcinoid syndrome, or isoniazid therapy—can precipitate Pellagra.

Other vitamins listed do not produce this syndrome: biotin deficiency causes dermatitis and other symptoms but not the pellagra triad; folic acid deficiency leads to macrocytic anemia and related issues; thiamine deficiency causes beriberi and Wernicke–Korsakoff syndrome.