pellagra

“A nutritional deficiency disease that is characterized by deficiency of niacin (vitamin B3), has_symptom gastrointestinal disturbance, anorexia, diarrhea, dementia, hallucinations, depression, psychosis, and/or non-specific skin changes, and has_material_basis_in deficiency of niacin, often from inadequate diet, malabsorption, or medication side effects.”