Pellagra is a disease condition caused by vitamin B3 or niacinamide deficiency. It is characterized by the 3 Ds- dermatitis, diarrhea and dementia.
Historically, pellagra was described as early as 1735 by Don Gasper Casal, a Spanish court physician. He named this condition pellagra meaning rough skin due to the predominant finding of scaly, rough skin among the peasants of certain parts of Spain where, poverty was rampant and prevented these patients from having adequate intake of the vitamin in their diet. This condition was especially common in the regions of Europe where maize was the staple diet. The link between pellagra and vitamin niacinamide was discovered much later in the USA, almost 2 centuries later.
Pellagra can be either primary or secondary
Primary pellagra is caused by deficiency of vitamin B3 or niacin in the diet. Secondary pellagra is the condition resulting from deficiency of tryptophan (an essential amino acid) in the diet. Tryptophan is essential because it is a precursor for the synthesis of niacinamide. Even if this amino acid is consumed in sufficient quantities any process that interferes with its conversion to vitamin B3 can cause a deficiency of vitamin B3. The reason so many suffered from pellagra in the past is that maize was the staple crop in large parts of Europe and USA. Maize is deficient in both tryptophan and Niacin in its unfortified form. This discovery caused maize to subsequently to be marketed in a fortified form (with niacin), a practice that is prevalent today.
As stated previously, pellagra is characterized by diarrhea, dementia and dermatitis. The first clinical presentation is almost always that of Gastro-intestinal symptoms. Almost always the first symptom is that of mucosal atrophy, with the changes being visible on the tongue as redness with a smooth featureless appearance of the surface. This is the result of atrophy of the papillae of the tongue.
Some of the first symptoms of pellagra include malaise, apathy, weakness, and lassitude. The gastro-intestinal symptoms include malabsorption and failure to thrive. Irritable bowel syndrome can also be a sign of pellagra with diarrhea a main symptom.
The skin disease in pellagra usually affects the parts of the body that are exposed to sunlight. The skin becomes rough and scaly with reddening in the early stages. The histopathological features include vascular dilatation, proliferation of endothelial lining, perivascular lymphocytic infiltration, and hyperkeratinization and subsequent atrophy of the epidermis. The skin also becomes dark (hyperpigmentation) and thickened with presence of bullae or fluid filled vesicles on the surface. Many patients complain of a burning sensation of the affected skin. The nervous system is also affected with degenerative changes seen in the neurons (nerve cells). The nervous system changes result in anxiety, delusions, hallucinations, headaches, insomnia, and stupor. The end stage is a condition called dementia wherein the brain undergoes atrophy. Still untreated, pellagra can cause death as a result of the inability of the body to supply sufficient energy for the vital body functions due to depletion of the substances required for this function.