Niacin Deficiency Symptoms

by on June 18, 2012

What is Niacin Deficiency?

Niacin deficiency occurs when a person has inadequate intake or has impaired absorption of niacin or tryptophan. Secondary deficiency can also occur due to other medical conditions particularly alcoholism, cirrhosis and diarrhea. Prolonged use of tuberculosis drug - isoniazid (Laniazid, Nydrazid) – can also cause niacin deficiency.

Niacin (also known as vitamin B3 or nicotinic acid) is a member of the B vitamin family. Like other B-complex vitamins, it plays a crucial role in the conversion of carbohydrates into glucose, metabolism of proteins and fats, and ensure healthy nervous system. It also plays a crucial role in the production of hormones, particularly sex and stress hormones, effective blood circulation, and regulation of cholesterol levels.

Tryptophan, one of the 10 essential acids, is also an important source of niacin in the body. This amino acid, commonly found in high-protein foods such as milk and meats, is converted by the liver to niacin.

Basically, dietary niacin deficiency is unlikely in developed countries because most food products are fortified with this vitamin. Symptoms of niacin deficiency are known as “three D’s”: Dermatitis (skin pigmented rash), Diarrhea (gastroenteritis), and Dementia (widespread neurologic deficits particularly cognitive decline).

Since vitamin B3 is essential in energy production, a deficiency with this vitamin can lead to body weakness and lack of appetite. It can also lead to skin infections.

Symptoms of Niacin Deficiency

Mild niacin deficiency can cause symptoms that include:

  • canker sores
  • depression
  • fatigue
  • indigestion
  • vomiting

Severe niacin deficiency, also known as pellagra, can cause a wide array of symptoms involving the skin, digestive system, and nervous system. Some of the symptoms include:

  • localized skin pigmentation or rash on skin exposed to sunlight
  • swollen mouth
  • bright red tongue
  • apathy
  • headache
  • vomiting and diarrhea
  • fatigue
  • depression
  • memory loss
  • disorientation

If not treated, severe niacin deficiency or pellagra can lead to death.


Niacin deficiency is diagnosed through clinical evaluation. Diagnosis may be straightforward when the clinical picture of niacin deficiency is evident. However, the clinical presentation may not be specific. Often, differentiating the symptoms is quite difficult. A history of inadequate niacin or tryptophan intake can help confirm diagnosis. In addition, laboratory tests can help confirm the diagnosis, especially if it is unclear. A urine test may be done to determine niacin deficiency.


Use of dietary supplements containing niacin and its derivatives (nicotinamide) is often successful in the treatment of this vitamin deficiency. Since the niacin deficiency is usually accompanied by multiple vitamin deficiencies, a well-balanced diet along with complete multivitamin supplement is necessary to treat the deficiency. The vitamin dosage ranges from 40 to 250 mg per day taken in 3 or 4 divided doses.