Niacin deficiency

Pellagra is a disease caused by a deficiency of niacin (vitamin B3) or its precursor, tryptophan, due to various reasons. It primarily affects the skin and mucous membranes, digestive system, and neuropsychiatric system. It can occur at any age, but in China, it is more common in young and middle-aged women. Clinically, it manifests as dermatitis, diarrhea, and dementia.