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Water-soluble vitamin

Vitamin B3

niacin

NAD/NADP coenzymes for energy metabolism, DNA repair, cell signaling

Essential nutrient

Reference intakes (RDA or AI) are set by the National Academies of Sciences, Engineering, and Medicine. Deficiency thresholds come from clinical and WHO guidance.

At a glance

Women, 19-50

14 mg NE

Men, 19-50

16 mg NE

Upper limit (adults)

35 mg/day (from supplements/fortified foods)

How common is deficiency?

Uncommon in developed countries; occurs in maize-dependent diets and alcohol use disorder

Food sources

Animal sources

Chicken, turkey, beef, pork, tuna, salmon, liver

Plant sources

Peanuts, brown rice, whole grains, mushrooms, green peas, fortified cereals, potatoes

Deficiency and testing

Signs of deficiency

Pellagra - the '4 Ds': dermatitis (sun-exposed skin), diarrhea, dementia/confusion, death if untreated; sore tongue, fatigue

Who is at higher risk

Alcohol use disorder, populations eating untreated maize as staple, carcinoid syndrome, Hartnup disease, anorexia, isoniazid therapy

How it is tested

Urinary N1-methylnicotinamide (and 2-pyridone) excretion; whole-blood NAD level (research)

Cut-offs

Urinary N1-methylnicotinamide <0.8 mg/day (or <0.5 mg/g creatinine) suggests deficiency

Symptoms are not specific. Only a clinician with the right tests can tell whether you are deficient.

Supplement forms

Common forms

nicotinic acid (niacin), nicotinamide (niacinamide), inositol hexanicotinate ('no-flush'), nicotinamide riboside (NR), NMN.

More effective

nicotinamide to correct deficiency/pellagra without flushing; nicotinic acid (prescription doses, under medical care) for lipid lowering; NR may raise blood NAD levels (human data on health outcomes still limited).

Less effective

'no-flush' inositol hexanicotinate (little free niacin released, so little lipid effect); high-dose nicotinic acid (flushing, liver stress, raised blood sugar); NMN and NR for anti-aging (insufficient clinical evidence).

Safety, interactions and halal notes

Safety and interactions

Upper limit for adults: 35 mg/day (from supplements/fortified foods). Going above the upper limit over time can cause harm, so check labels and talk to a clinician before high-dose supplements.

Halal note

The nutrient itself is not a halal question. For supplements, check the delivery form: gelatin (pork or non-halal bovine), capsule shells, glycerin, and alcohol-based carriers need halal certification. Ask for the halal certificate, not just a label claim. This is general guidance, not a certification.

Frequently asked questions

How much Vitamin B3 do adults need per day?

Women 19-50: 14 mg NE. Men 19-50: 16 mg NE. Upper limit: 35 mg/day (from supplements/fortified foods). Needs change with age, pregnancy and health conditions.

What are the signs of Vitamin B3 deficiency?

Pellagra - the '4 Ds': dermatitis (sun-exposed skin), diarrhea, dementia/confusion, death if untreated; sore tongue, fatigue. These signs are not specific, so only a clinician with the right tests can confirm a deficiency.

What are the best food sources of Vitamin B3?

Animal sources: Chicken, turkey, beef, pork, tuna, salmon, liver. Plant sources: Peanuts, brown rice, whole grains, mushrooms, green peas, fortified cereals, potatoes.

Which form of Vitamin B3 supplement is best?

Sources

NIH Office of Dietary Supplements fact sheet

← Back to the full nutrient guide

This page is for education only and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to a qualified clinician before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a medical condition. Daily needs are US reference intakes for adults 19-50.

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