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Vitamin B3 (Niacin) - Deficiency Risk and Symptoms

2 min read

Nutrient Name

Vitamin B3 - otherwise known as Niacin

Potential for deficiency


Niacin deficiency is a condition that occurs when a person doesn't get enough or can't absorb niacin or tryptophan. Most people in the developed world get plenty of niacin in their diets therefore deficiency is relatively uncommon. Niacin deficiency is more likely to be caused by problems that affect absorption of niacin or tryptophan, with the most common reason being alcoholism. Disorders of the digestive system which affect absorption of nutrients is another cause.

What does Vitamin B3 do?

Like all of the 8 B vitamins, niacin plays a role in converting carbohydrates into glucose, metabolising fats and proteins, and keeping the nervous system working properly. B-complex vitamins are needed for a healthy liver, healthy skin, hair, and eyes, and to help the nervous system function properly. Niacin also helps the body make sex- and stress-related hormones. It also helps improves circulation and cholesterol levels and has been shown to suppress inflammation.

The European Food Safety Authority (EFSA) confirms that clear health benefits have been established for the dietary intake of Niacin (Vitamin B3) in contributing to: 

  • normal energy-yielding metabolism
  • the normal function of the nervous system
  • the maintenance of normal skin and mucous membranes
  • normal psychological functions
  • the reduction of tiredness and fatigue.

Food Sources

Red meat, fish (salmon, swordfish and tuna), poultry (chicken or turkey), fortified breads and cereals, beets, brewer's yeast, sunflower seeds and peanuts.

Niacin (Vitamin B3) is a water-soluble vitamin and as such, it is unlikely to reach toxic levels. There is little danger of niacin toxicity when it is taken orally. Dosage of more than 2000 mg per day is known to cause side effects however this is extremely high and is unlikely to be consumed.

Symptoms of deficiency

  • Indigestion
  • Fatigue
  • Canker sores (ulcers)
  • Vomiting
  • Poor circulation
  • Depression
  • Severe deficiency is called Pellagra and is characterised by cracked, scaly skin, dementia, and diarrhea
A healthy balanced diet is the best way to consume all the nutrients we need. Sometimes however this isn't possible and then supplements can help. This article isn't intended to replace medical advice. Please consult your healthcare professional before trying any supplements or herbal medicines.