What nutritional deficiency leads to the three "D's" of pellagra?

The three "D's" associated with pellagra are dermatitis, diarrhea, and dementia, which are classic manifestations of niacin (vitamin B3) deficiency. Niacin is essential for the synthesis of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are critical coenzymes involved in numerous metabolic processes, including those that generate energy from carbohydrates, fats, and proteins.

When the body lacks sufficient niacin, these metabolic processes become impaired, leading to the symptoms that characterize pellagra. Dermatitis typically presents as a photosensitive rash, commonly on areas exposed to sunlight, diarrhea results from gastrointestinal disturbances, and dementia or cognitive decline occurs due to the impact of the deficiency on brain function.

The other nutrients listed have different roles in the body and do not lead to the three "D's" of pellagra. Vitamin B12 deficiency, for example, primarily results in megaloblastic anemia and neurological symptoms. Folic acid deficiency also leads to megaloblastic anemia, particularly seen in pregnancy and certain hematological conditions. Vitamin C deficiency is associated with scurvy, characterized by symptoms like gingival bleeding, joint pain, and skin issues, but