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Vitamins & minerals health centre

Vitamin B3 (niacin, nicotinic acid)

Vitamin B3 - what does it do?

Vitamin B3, also known as niacin or nicotinic acid, plays an important role in metabolism, helping the body release energy from dietary carbohydrate. Vitamin B3 also helps the body use protein and fats effectively. It’s essential for a healthy circulation and digestive system.

Vitamin B3 is vital for a healthy nervous system and to help the body produce sex and stress hormones. It’s found in food in the form of nicotinic acid or nicotinamide, and can also be made in our body by our liver from tryptophan, a constituent of dietary protein.

How much vitamin B3 do we need?

In the UK the adult RNI (Reference Nutrient Intake) is 17mg a day for men and 13mg daily for women. An additional 2.3mg daily is recommended for breastfeeding women but in reality there is no need for any additional vitamin given it can be made from the tryptophan in dietary protein. The European Union (EU) RDA suggests 18mg a day as a recommended daily amount for adults.

Vitamin B3 uses

It’s rare to have a vitamin B3 deficiency, but it may be present in people with malnutrition and alcohol abuse. Strict vegetarians and vegans may also at risk of vitamin B3 deficiency. Low levels of niacin can lead to skin disorders, diarrhoea, indigestion and fatigue. A sore mouth, vomiting, constipation and diarrhoea may also develop with increasing deficiency. Neurological symptoms associated with deficiency include fatigue, insomnia, depression, visual impairment and memory loss.

Severe and prolonged vitamin B3 deficiency can manifest as pellagra, a skin condition most pronounced on the parts of the skin exposed to sunlight.

Vitamin B3 has been studied as a treatment for many diseases and conditions including high blood cholesterol, type 1 diabetes, intermittent claudication, the symptoms of premenstrual syndrome (PMS) and osteoarthritis.

Some of these trials used high doses of vitamin B3. Seek medical advice before taking high doses of vitamin B3 supplements for any of these conditions.

Vitamin B3 food sources

Sources of dietary vitamin B3 include:

  • Cows milk
  • Eggs
  • UK white flour (fortified by law with no less than 1.6mg/100g flour)
  • Peanuts
  • Fresh fruit and vegetables
  • Meat, especially beef, pork,
  • Fish
  • Yeast and yeast extracts eg Marmite
  • Fortified breakfast cereals

Vitamin B3 supplements

Vitamin B3 supplements are available as a single vitamin, as part of a B group complex supplement, or within a general multivitamin and mineral supplement. The amount provided in supplements range from 0.25mg to 150mg per day in general supplements, and up to 250mg of nicotinamide as a single dose supplement.

There’s a lack of evidence for the use of Vitamin B3 supplements during pregnancy or breastfeeding. If you are pregnant choose supplements specific for pregnancy and avoid single nutrient supplements.

WebMD Medical Reference

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