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Pellagra is a deficiency disease that is due to a lack of the vitamin niacin or a substance called tryptophan. The disease mainly affects people in poor countries who eat a diet based on maize. Symptoms of pellagra range from nervous system issues, like confusion or delusions, to skin issues and internal problems, such as diarrhea.
According to the World Health Organization (WHO), the origin of the name pellagra derives from the Italian words pelle and agra, which mean rough skin. First described in Europe in poor peasant populations after the introduction of maize to the continent, the disease spread wherever maize became a staple food. The skin issues that the disease causes are distinctive. Areas of skin that are usually uncovered and in sunlight become red, so the skin appears sunburned with a clear difference between affected and unaffected skin. These areas, however, are also itchy.
Sometimes, the affected skin blisters, but more often, it turns crusted and hard. This scaly skin often runs in a band around the neck, which is also known by the names Casals collar or Casals necklace. Only very rarely does pellagra occur without skin irritation.
A description of the symptoms of pellagra can be summarized as the four Ds. Dermatitis, which refers to the skin irritation, is the first D. The second D refers to diarrhea. Pellagra causes health issues from the mouth down through the gastrointestinal tract.
The tongue swells and turns an abnormally red color, and the mouth hurts. Pellagra sufferers feel nauseated and produce an unusually high amount of saliva. Inflammation of the stomach and watery or bloody diarrhea are also symptoms.
Dementia is the third D in the list of symptoms of pellagra. Sufferers' nervous systems can become affected, resulting in mental symptoms such as depression, anxiousness, and lethargy. After these issues come problems like headache, increased irritability, and muscle tremors. Dementia develops in a minority of patients.
Early, nonspecific symptoms of pellagra include weight loss, loss of appetite, and a reduction in normal strength. Mild gastrointestinal problems like diarrhea or constipation are also early signs. A general feeling of weakness or lethargy can also be symptomatic.
Death is the fourth D to describe pellagra. Native Americans, who subsisted on a mostly maize-based diet, did not suffer and die from pellagra like other maize eaters in the countries maize was introduced to. This stems from the traditional American manner of preparing maize, which involved the addition of wood ash or lime. This preparation improves the ability of the body to utilize the niacin present in the food, compared to preparation techniques in the rest of the world.