Pellagra is a disease which appears when people are in the late stages of a niacin or tryptophan deficiency. Doctors famously recognize pellagra by the four D's: dementia, dermatitis, diarrhea, and death. In addition to these well known symptoms, pellagra can also cause a number of associated health problems. If the condition is not treated, the patient will die in four to five years.
This extreme nutritional deficiency has been recorded in human populations since at least the 1700s. In many societies, it is most commonly seen among people who are poor, with limited access to nutrition, along with chronic alcoholics, anorexics, and people with severe mental illness who may refuse to eat. Certain digestive tract disorders can also lead to pellagra, as patients with these conditions may not be able to absorb the nutrients they need. Historically, pellagra is also seen in communities where people rely heavily on corn for nutrition, because corn lacks available niacin unless it is treated with lime in a process known as nixtamalization.
A notable outbreak of pellagra occurred in the American South in the early 20th century, spurring researchers to find out what was causing the rash of medical problems and deaths in the South. These researchers eventually identified the issue as a nutritional deficiency, and developed treatments to address pellagra. Concerns about pellagra and other nutritional deficiencies have also led some governments to mandate supplementation of certain foods with necessary vitamins and minerals, to ensure that populations have access to all of the components of a healthy diet.
Patients with this condition start with a simple nutritional deficiency. As the deficiency becomes more severe, a photosensitive rash appears on the skin, and the patient may start to experience digestive upset. The next symptoms to emerge are neurological, with patients having trouble balancing, and eventually developing dementia. If the pellagra is allowed to persist, the patient will eventually die as a result of the tryptophan or niacin deficiency.
The treatment for pellagra is nicotinic acid, accompanied by dietary modifications to ensure that the patient will get the nutrition he or she needs in the future. Many foods provide sources of tryptophan and niacin, including poultry, organ meats, wheat, yeast, and peanuts, and people who eat a balanced diet can generally avoid developing this nutritional deficiency along with many others. Dietary supplementation can also be used for people who have a limited access to fresh foods which are rich in necessary vitamins and minerals.