Pellagra is a condition that occurs due to a lack of vitamin B-3, otherwise known as niacin.

It can cause many symptoms, but the most common are diarrhea, dermatitis, and dementia. Without diagnosis and treatment, pellagra can be life threatening.

In this article, learn more about pellagra, including the risk factors and treatment options.

Pellagra is a disorder that occurs when a person does not get enough niacin, or vitamin B-3.

There are two types of pellagra: primary and secondary. Primary pellagra comes from not getting enough niacin in the diet, whereas secondary pellagra develops when the body is unable to absorb niacin.

There is niacin in animal proteins, fruits, and vegetables. The body can also make niacin using essential amino acids.

The body acquires these amino acids from other foods, such as chicken and sunflower seeds.

Primary pellagra is more common in places where people rely on a diet of maize, as the niacin in corn is in the form of niacytin, which people cannot digest and absorb.

Some conditions, such as alcohol use disorder and HIV, stop the body from absorbing niacin and can cause secondary pellagra.

Pellagra causes gastrointestinal, skin, and neurological issues. The primary symptoms are:

  • diarrhea
  • skin inflammation
  • dementia

Gastrointestinal symptoms

The most common gastrointestinal issue is diarrhea. Diarrhea is the passing of loose, watery stools at least three times per day.

Diarrhea can lead to dangerous dehydration, and it can cause malnutrition over time, as it can affect the absorption of nutrients from food. It is also often the first symptom of pellagra to appear.

Other gastrointestinal symptoms include:

  • vomiting
  • abdominal pain
  • nausea
  • indigestion
  • decreased appetite
  • oral ulcers
  • tongue swelling

Dermatological symptoms

Pellagra-related dermatitis often causes thickened and scaly skin, rashes, and discoloration.

Doctors refer to the appearance of these symptoms around the neck as a Casal collar or Casal necklace. The affected area of skin may become sensitive to light and feel and look like a sunburn.

Other dermatological symptoms include cheilitis, which is the cracking and inflammation of the corners of the mouth, and angular palpebritis, which causes redness and cracking in the eyelid corners.

Neurological symptoms

Some neurological conditions, such as anxiety and depression, are early symptoms of pellagra.

As pellagra advances, people may experience symptoms of dementia, including:

  • memory loss
  • delusions
  • confusion
  • in some cases, psychosis

There are three main symptoms of alcohol-induced pellagra that relate to the brain and nerves. These are:

  • intermittent confusion
  • stiff muscles that are hard to use
  • exaggerated startle responses

Without treatment, pellagra can be life threatening and lead to death.

The underlying causes of primary and secondary pellagra are different.

Primary pellagra occurs if a person’s diet is low in niacin. The people who are most at risk of getting primary pellagra are those whose diet relies mainly on maize.

It is very rare in developed countries, where manufacturers routinely fortify flour with niacin.

A person who cannot absorb vitamin B-3, despite having a diet rich in niacin, may develop secondary pellagra. A significant risk factor for secondary pellagra is alcohol use disorder.

An article from 2014 suggests that alcohol use disorder can cause pellagra through malnutrition. A person may not be eating enough food containing niacin, and the alcohol can prevent the body from absorbing it.

Alcohol can also stop certain proteins from turning into niacin, increasing the risk of pellagra developing.

However, alcohol-induced pellagra often goes undetected because its presentation is similar to that of alcohol-withdrawal delirium.

Other risk factors for secondary pellagra include:

  • malnutrition from homelessness, anorexia, HIV, or end stage cancer
  • Crohn’s disease
  • Hartnup disease
  • dialysis
  • certain drugs, such as isoniazid for tuberculosis
  • carcinoid syndrome, a collection of symptoms due to carcinoid tumors

A doctor will be able to diagnose pellagra if diarrhea, dermatitis, and dementia are all present simultaneously.

However, the condition can be more difficult to diagnose if these symptoms do not show up at the same time. A doctor may test the person’s urine and blood to check whether there is a niacin deficiency along with other pellagra-associated abnormalities.

People can treat primary pellagra by eating a diet rich in niacin. Meat, eggs, fish, and legumes, such as peas and lentils, are high in niacin. However, a doctor will likely prescribe vitamin supplements to help a person regain healthy levels of niacin.

Treatment for secondary pellagra is similar, but doctors will also treat the underlying cause.

Symptoms should begin to improve quickly. Doctors may prescribe high doses of niacin for 5 days, and the person will typically see improvements in their symptoms within 2 days.

Pellagra is a serious condition that can severely affect a person’s quality of life and health, potentially leading to death. It is vital to see a doctor if the symptoms of pellagra appear.

To avoid pellagra, it is important to consume the recommended daily allowance (RDA) of niacin.

The RDA of niacin is:

  • 14–16 milligrams (mg) per day for adults
  • 18 mg per day for those who are pregnant or breastfeeding
  • 6–16 mg per day for people under the age of 18 years

However, most people who do not rely on maize for food will not develop primary pellagra.

Once a person receives treatment for both pellagra and any underlying conditions, it is possible to regain full health.