TempoLife › Features › Reference intakes by nutrient, age and sex › niacin

Niacin (B3): the daily reference intake

Niacin is the only vitamin the body can make for itself, from the amino acid tryptophan, and its reference intake is written in a unit that reflects that: niacin equivalents, where 60 mg of tryptophan counts as 1 mg of niacin. EFSA sets 1.6 mg NE per megajoule of energy eaten.

These are published population reference values, not a diagnosis and not a prescription. A reference intake describes what covers a healthy group; it cannot tell you your own status, and no page can. Pregnancy, chronic illness, medicines and malabsorption all change the picture — take those questions to a doctor, midwife, pharmacist or dietitian.

The requirement at different energy intakes

Like thiamin, niacin is published per unit of energy rather than per day: 1.6 mg of niacin equivalents per megajoule. A niacin equivalent is 1 mg of niacin or 60 mg of dietary tryptophan.

Niacin equivalents, and why the food table understates

One niacin equivalent is either 1 mg of preformed niacin or 60 mg of dietary tryptophan. Because protein is roughly 1 per cent tryptophan, a diet with adequate protein contributes a substantial share of its niacin requirement through that route, and a high-protein meal can supply more niacin equivalents from its tryptophan than from its niacin.

Food composition tables, including the one used here, report preformed niacin in milligrams and not niacin equivalents. So the food table below systematically understates against a target written in NE, and it understates most for protein-rich foods. That is a limitation of the data, stated rather than hidden.

Pellagra and the maize lesson

Severe niacin deficiency is pellagra: dermatitis on sun-exposed skin, diarrhoea and dementia. Historically it struck populations dependent on maize, because the niacin in maize is chemically bound and unavailable — unless the grain is treated with alkali, as in the traditional nixtamalisation used in Mesoamerica, which releases it. Populations that adopted maize without the technique got the disease; those that kept it did not.

It is one of the neatest illustrations in all of nutrition that a food composition figure is not the same as what the eater absorbs.

The two supplemental forms behave completely differently

Nicotinic acid at pharmacological doses causes an intense skin flush — heat, redness and itching across the face and upper body — through prostaglandin-mediated vasodilation. That reaction, not toxicity, is what sets its 10 mg upper level. Nicotinamide does not flush and has an upper level of 900 mg.

This is a common source of confusion in the supplement aisle, because both are sold as "vitamin B3" and their safe amounts differ by nearly a hundredfold. High-dose nicotinic acid has also been used as a lipid-lowering drug under medical supervision, which is a different context again.

Where it comes from

Meat, poultry, fish, peanuts and wholegrain cereals are the main sources of preformed niacin, and any adequate protein intake supplies tryptophan on top. Deficiency in a European diet is rare outside chronic alcohol use and severe malabsorption.

The upper level

EFSA and its predecessor set separate upper levels for the two supplemental forms rather than for niacin in food: 10 mg a day for nicotinic acid and 900 mg a day for nicotinamide in adults. The low nicotinic acid figure reflects the flushing reaction rather than organ damage.

Ordinary food against the requirement at a 10 MJ energy intake

Top of this list: Chicken breast, 16.5 mg preformed niacin in a 120 g serving (a breast) — 103% of the requirement at a 10 MJ energy intake. One serving covers the whole day on its own.

Unit: The reference value is in niacin equivalents (NE), which count 60 mg of dietary tryptophan as 1 mg of niacin. The composition data is preformed niacin only, so every row here understates against the target, and protein-rich rows understate most.

Portion sizes are ordinary household servings chosen for this table, not official reference portions, and the shortlist is an editorial one: everyday foods eaten in this region rather than the highest per-100 g entries in the database. A raw per-100 g ranking would be topped by dried herbs, drink powders and fortified breakfast cereals, which answers a different question. The composition data is American, so where US fortification practice differs from European practice the row carries a dagger and the reason. For the full per-100 g ranking of a nutrient, the food-data section of this site publishes one.

Sources: EFSA Dietary Reference Values · Regulation (EU) No 1169/2011, Annex XIII · USDA FoodData Central SR Legacy (food composition) · EFSA scientific opinion on dietary reference values for niacin (2014) · Regulation (EU) No 1169/2011, Annex XIII · checked 2026-09-06

Frequently asked questions