Pellagra is caused by deficiency of which nutrient?

• A. Sodium
• B. Folate
• C. Niacin
• D. Vitamin D

Answer: (C)

Pellagra comes from not having enough niacin, which is vitamin B3. Niacin is needed to make the coenzymes NAD+ and NADP+, which carry out many redox reactions in energy metabolism. When niacin is deficient, tissues that rely heavily on these processes develop the characteristic symptoms: a dermatitis that often affects sun-exposed skin, diarrhea, and neurocognitive changes such as dementia. Historically this condition appeared in populations that ate a lot of corn as a staple without processing it (nixtamalization), which makes niacin less available. Niacin can also be made in the body from tryptophan, but that requires sufficient protein intake and other nutrients for the conversion to occur.

Other options don’t cause pellagra: sodium deficiency is an electrolyte issue, folate deficiency leads to megaloblastic anemia and related problems, and vitamin D deficiency causes bone problems like rickets or osteomalacia.