Vitamin B3 (Niacin)

Description Niacin is water soluble and is part of the B-vitamins group. Vitamin B3 comes in two common forms: Nicotinamide (the active form) and Nicotinic Acid.
Function/ Used for Niacin is vital for energy release in tissues and cells. It helps form NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate), two coenzymes which are involved in the release of energy from food.

Niacin helps maintain healthy nervous and digestive systems. It is also essential for normal growth and for healthy skin and contributes to a reduction in tiredness and fatigue.

Intake Recommended intake

EU NRV: 16mg (nicotinamide)


Niacin requirements depend on energy intake; values are therefore given as mg/1000 kcal and also as total values based on estimated average energy requirements for the majority of people in the UK.


UK average daily intake

Requirements vary depending on age and gender. The UK National Diet and Nutrition Survey lists up-to-date intake requirements and average intakes1.


As a supplement Not generally available as a single supplement. Commonly available as part of a multivitamin and mineral formula.

Different multivitamin and minerals products will vary in the percentage NRVs they include. People should always check the label for information about a specific product.

Found in (dietary sources) Meat, oily fish, poultry, bread, potatoes and breakfast cereals. Niacin can be synthesised from tryptophan (an essential amino acid).
Deficiency Niacin deficiency (rare in the UK) may lead to pellagra which means ‘raw skin’.

Early signs of deficiency are vague and non-specific and may include loss of appetite, headache, nausea, fatigue, mouth ulcers, dry skin, difficulty sleeping, poor memory and irritability.

The severe deficiency state of pellagra is characterised by dermatitis (predominantly in the areas of skin exposed to sunlight), dementia (associated with confusion, disorientation, seizures and hallucinations) and  diarrhoea.3

Precautions and contraindications Large doses of niacin are best avoided in gout (may increase uric acid levels); peptic ulcer (large doses may activate an ulcer); and liver disease (large doses cause deterioration). Large doses should also be used with caution in diabetes mellitus.3


Safe Upper Level: 500mg/day2 (nicotinamide); 17mg/day2 (nicotinic acid).

Use in pregnancy and breastfeeding There is no evidence of adverse effects in pregnancy.
Interactions e.g. with other medications Prolonged use of oral contraceptives may induce niacin deficiency.

Adequate amounts of all B vitamins are required for optimal functioning; deficiency or excess of one B vitamin may lead to abnormalities in the metabolism of another.3

Adverse effects Doses of over 150mg of the nicotinic acid form may cause temporary flushing of the skin in some people.
References 1.

2.     Expert Group on Vitamins and Minerals, 2003.

3.     Mason, P. Dietary Supplements. Pharmaceutical Press, London, 2001.