Pellagra is a remarkable chronic wasting disorder, the late stage of a severe cellular deficiency of niacin (vitamin B3). The classical triad of pellagra is dermatitis, diarrhea and dementia. Early symptoms include lassitude, weakness, loss of appetite, mild digestive disturbances and psychiatric distress. The dermatitis caused by pellagra is a bilaterally symmetrical eruption at cutaneous sites of solar exposure. It tends to be painful to touch during the acute phase and can eventually become so clinically striking that the patient may become ostracized. Untreated pellagra results in death from multiorgan failure. Pellagra used to be a disease of epidemic proportions in the developed world. In the 18th century, it was linked with poverty and subsistence on nutritionally marginal corn-based diets. In the 1940s and 1950s, with expanded biochemical knowledge, pellagra was reformulated as a deficiency disease due to inadequate niacin and its amino acid precursor tryptophan. It is currently seen in association with other conditions of chronic nutritional deficiencies, like alcoholism.
