How much niacin (vitamin B3) do adults need?

Adults need 16 milligrams for men and 14 milligrams for women (US, NIH). In the UK: 16.5 milligrams a day for men and 13.2 milligrams for women (NHS).

What is the upper limit for niacin (vitamin B3)?

US: 35 milligrams a day from supplements and fortified foods. UK (NHS): up to 17 milligrams a day of nicotinic acid from supplements is unlikely to cause harm.

Which foods have niacin (vitamin B3)?

Meat and poultry, fish, brown rice, nuts and seeds, beans, fortified bread and cereals.

What should I watch out for with niacin (vitamin B3)?

Above the upper limit, niacin often causes flushing: red, warm, itchy skin. Prescription doses are much higher and are taken only under a doctor.

Niacin (vitamin B3): what it does and how much you need

Niacin (vitamin B3) helps turn food into energy and keeps the nervous system, digestive system and skin healthy. Adults need 16 milligrams for men and 14 milligrams for women, and the upper limit is 35 milligrams a day from supplements and fortified foods.

Checked 28 September 2026 with Supplement Check's data from the NIH fact sheet and NHS guidance · Adults only

General information, not medical advice. Check with a doctor or pharmacist before taking a supplement, especially if you are pregnant or breastfeeding, take any medicine, or are under 18.

In the UK

In the UK, adults need 16.5 milligrams a day for men and 13.2 milligrams for women, and the NHS says up to 17 milligrams a day of nicotinic acid from supplements is unlikely to cause harm.

How much you need and the upper limit

	US (NIH)	UK (NHS)
Adults need	16 milligrams for men and 14 milligrams for women	16.5 milligrams a day for men and 13.2 milligrams for women
Upper limit	35 milligrams a day from supplements and fortified foods	Up to 17 milligrams a day of nicotinic acid from supplements

The UK figure is the amount the NHS says is unlikely to cause harm. Figures are for adults.

Cautions

Above the upper limit, niacin often causes flushing: red, warm, itchy skin. Prescription doses are much higher and are taken only under a doctor.

Food sources

Meat and poultry
Fish
Brown rice
Nuts and seeds
Beans
Fortified bread and cereals

Dose questions

Is 500 mg of niacin too much?

Quick answers

What does niacin (vitamin B3) do?: Niacin (vitamin B3) helps turn food into energy and keeps the nervous system, digestive system and skin healthy.
How much niacin (vitamin B3) do adults need?: Adults need 16 milligrams for men and 14 milligrams for women (US, NIH). In the UK: 16.5 milligrams a day for men and 13.2 milligrams for women (NHS).
What is the upper limit for niacin (vitamin B3)?: US: 35 milligrams a day from supplements and fortified foods. UK (NHS): up to 17 milligrams a day of nicotinic acid from supplements is unlikely to cause harm.
Which foods have niacin (vitamin B3)?: Meat and poultry, fish, brown rice, nuts and seeds, beans, fortified bread and cereals.
What should I watch out for with niacin (vitamin B3)?: Above the upper limit, niacin often causes flushing: red, warm, itchy skin. Prescription doses are much higher and are taken only under a doctor.

Sources

NIH Office of Dietary Supplements fact sheet
https://ods.od.nih.gov/factsheets/Niacin-HealthProfessional/
NHS vitamins and minerals guidance
https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-b/

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