How much niacin (B3) do you need per day?

The RDA for niacin is 16 mg NE a day for adult men and 14 mg NE for adult women aged 19 and over.

These are the reference amounts used on US food labels and in dietary guidance, not personal targets. What you need shifts with age, pregnancy, medication and health conditions. The % Daily Value shown on every food page here is calculated against the FDA Daily Value for niacin (B3), which is 16 mg a day.

What this means for you

Sixteen milligrams a day for men and fourteen for women, and a single chicken breast covers it. Meat, fish, poultry, peanuts and fortified grains carry most of the niacin in an ordinary diet.

There is also a second supply line that no other vitamin has. The body makes niacin out of tryptophan, an amino acid in protein, which is why the unit on the label is "NE", niacin equivalents, and why deficiency is rare wherever protein is.

That conversion has a catch worth knowing. If you are short of riboflavin, vitamin B6 or iron, it works less well, because the enzymes doing the work need those nutrients. A niacin problem is often a different shortage in disguise.

Myth. High-dose niacin was prescribed for years to raise HDL cholesterol and prevent heart attacks. Across 23 randomised trials in 39,195 people, it did not reduce deaths, heart attacks or strokes. If you are taking gram-level niacin for your heart, that is the number to discuss with your doctor.

That failure is easier to swallow once you know the reputation had a real start. Pooling 11 trials in 6,616 patients from before statins were standard care, 1 to 3 grams a day of nicotinic acid cut major coronary events by 25 per cent and cardiovascular events of any kind by 27 per cent. The drug was doing useful work in a world where almost nothing else lowered cholesterol. Statins then changed what the comparison meant, and when the question was put again on top of a statin, niacin added nothing. The reputation was built in the first era and never updated for the second.

If you are pregnant or might be

Unsettled. Women whose niacin intake around conception was too low were 13 per cent likelier to have a baby with a birth defect, pooled across 14 studies in 35,743 women. Read the design before the number. Every one of those studies asked women about their eating after the outcome was already known, which is the setup most exposed to remembering the past to fit the present. The interval runs from 1.02 to 1.24 and nearly touches no effect at all, and no trial has tested any of it. Take it as one more reason to eat normally rather than as a reason to buy a supplement.

The upper limit of 35 mg applies to supplements and exists because of flushing, a hot prickly sensation in the face and chest. Unpleasant rather than dangerous, and food does not cause it.

Where the number really comes from

Niacin is counted in niacin equivalents, and that unit is doing more work than it looks. Two things sit inside it.

Your body makes niacin out of tryptophan, the amino acid in protein, at roughly 60 mg of tryptophan to 1 mg of niacin. A palm-sized piece of turkey breast, about 85 g, carries around 180 mg of tryptophan, so it is worth about 3 mg of niacin through that route before anyone counts the niacin in the meat itself.

Not for everyone. That conversion is not a fixed rate. It drops when tryptophan intake is low, in the inherited condition Hartnup disease where tryptophan is not absorbed properly, and when iron, riboflavin or vitamin B6 are short. So a person who looks niacin deficient may really be short of something else, and topping up niacin alone would leave the actual problem in place.

The second thing is that not all dietary niacin is available to you. Animal foods carry 5 to 10 mg a serving in a form the body takes up easily. Grains carry 2 to 5 mg, of which only about 30 per cent is available at all. Fortified flour carries the free form, which is fully available.

Almost nobody is near the line

Set against that, ordinary intake is not close to the requirement. In Nordic countries adults take in 29 to 31 niacin equivalents a day as women and 39 to 41 as men, against a recommendation in the 14 to 16 range. Average dietary protein on its own supplies 12 to 19 of them. Two to three times the recommendation, from eating normally and thinking about none of it.

That is the honest reason this page is short on advice. For a person eating a mixed diet, niacin is not a thing to manage. The reasons to read further are the supplement label and the drug interactions, and both are on other pages here.

Where the recommendation itself comes from

One thing worth knowing about the number at the top of this page is what sits under it.

Unsettled. The body that sets the Nordic recommendations says plainly that the past decade of niacin research makes no useful contribution to working out how much a healthy person needs. That research went into pharmacological doses of nicotinic acid for blood fats, and into NAD precursors sold as cellular boosters, and neither tells you anything about a requirement. The requirement is estimated instead from how much nicotinamide breakdown product turns up in urine. That is a biochemical marker rather than anything that happens to a person, and the very large recent literature about NAD has not changed it. The number is a reasonable estimate built on a proxy, and it is not a measured health threshold.

What a niacin label is allowed to claim

Established. No food or supplement sold in the United States may legally claim that niacin prevents or treats anything. A health claim is unlawful unless the regulations specifically provide for it, and the sections that do provide for one run without gaps from 101.72 to 101.83. They cover calcium and vitamin D, dietary lipids, sodium, saturated fat, fibre, fruits and vegetables, folate, sugar alcohols, soluble fibre, soy protein and plant sterols. Niacin is not among them, and no qualified claim exists for it either, which is the lower bar the regulator uses when evidence is suggestive without being conclusive.

That is easy to over-read, so here is the careful version. An empty register is a fact about the regulator rather than about the vitamin. It records that the evidence never reached the bar an authorised claim demands. It does not record that niacin does nothing, and niacin plainly does things, starting with preventing pellagra. What it gives you is two practical conclusions. Anyone printing a health promise about niacin on a package is outside the rules. And no authority has ever read the evidence and been persuaded, which is worth setting against any confident sentence on a bottle.

Written from the evidence cards and the data on this page, then checked back against the sources. Bioma Learn has no human medical reviewer at this time and we say so rather than invent one. Information, not medical advice. How we verify.

Foods highest in niacin (B3) on this site

• Acai berry drink, fortified fortified — 24.1 mg per 8 fl oz (151% DV)
• Chicken, breast, cooked, roasted — 19.2 mg per 1 cup, chopped or diced (120% DV)
• Chicken, light meat, cooked, roasted — 17.4 mg per 1 cup, chopped or diced (109% DV)
• Chicken, meatless, breaded, fried fortified — 16.6 mg per 1 cup, diced (104% DV)
• Chicken, broiler or fryers, breast, skinless, cooked — 16.4 mg per 1.0 piece (103% DV)

All niacin (B3) sources ranked →

Full guide: Niacin: the vitamin that became a heart drug and then failed the trials