Niacin (vitamin B3) is a water-soluble B vitamin that the body turns into NAD, a coenzyme more than 400 enzymes need, mainly to release energy from food1.
NAD helps move the energy in carbohydrates, fats and protein into ATP, the cell’s energy currency1.
NAD is needed by enzymes that maintain the genome, control gene expression and support cell communication1.
NADP, the second active form, enables the making of cholesterol and fatty acids1.
NADP plays a critical role in keeping up cells’ antioxidant function1.
Niacin helps the digestive system, skin and nerves work3.
NAD and NADP in food are turned into nicotinamide in the gut, niacin is absorbed mainly in the small intestine, and every tissue converts it into NAD1. The liver also makes NAD from some tryptophan and methylates excess niacin into metabolites that leave in urine1.
| Food and serving | Amount |
|---|---|
| Marinara sauce, ready to serve, 1 cup | 10.3 mg |
| Rice, brown, cooked, 1 cup | 5.2 mg |
| Peanuts, dry roasted, 1 oz | 4.2 mg |
| Breakfast cereal, fortified with 25% of the Daily Value | 4.0 mg |
| Rice, white, enriched, cooked, 1 cup | 2.3 mg |
| Potato (russet), baked, 1 medium | 2.3 mg |
| Sunflower seeds, dry roasted, 1 oz | 2.0 mg |
| Food and serving | Amount |
|---|---|
| Beef liver, pan fried, 3 oz | 14.9 mg |
| Chicken breast, grilled, 3 oz | 10.3 mg |
| Turkey breast, roasted, 3 oz | 10.0 mg |
| Salmon, sockeye, cooked, 3 oz | 8.6 mg |
| Tuna, light, canned in water, 3 oz | 8.6 mg |
| Pork tenderloin, roasted, 3 oz | 6.3 mg |
Amounts are niacin alone and do not include tryptophan, part of which the body turns into niacin. Niacin in some grains is bound and only partly available, while niacin added to enriched foods is readily absorbed1. Amounts per serving from1.
Many breads and cereals have added niacin, in a free form that is highly bioavailable1.
The liver can turn some tryptophan from protein into NAD, but how efficiently varies a lot between people1.
In multivitamins, B-complex and niacin-only products; some niacin-only products hold far more than the recommended amount1.
The same reference table draws the reference lines on your charts in Ayuvo. Needs differ in pregnancy and breastfeeding, which are not covered here.
| Age | Women | Men | Upper limit |
|---|---|---|---|
| 19–30 | 14 mg | 16 mg | 35 mg |
| 31–50 | 14 mg | 16 mg | 35 mg |
| 51–70 | 14 mg | 16 mg | 35 mg |
| 71+ | 14 mg | 16 mg | 35 mg |
RDA (Recommended Dietary Allowance) is the daily amount that meets the needs of nearly all healthy people. Per day, for adults14.
Upper limit (UL) is the most per day that is unlikely to cause harm. Applies only to niacin from supplements and fortified foods (nicotinic acid and nicotinamide), not niacin naturally in food.
The upper limit for niacin covers only part of your intake (from supplements and medicines only, not from food), so it is not drawn on this bar.
Signs like these have many possible causes. They are a reason to talk to a clinician, not to self-treat.
Severe deficiency causes pellagra, now uncommon in industrialized countries and mostly seen with very limited diets low in niacin and protein1.
Niacin naturally in food has no reported adverse effects, but nicotinic acid in supplements often causes flushing, and very high doses can cause serious side effects1.
Niacin levels in the blood are not reliable indicators of status. The most sensitive measure is a urine test: daily excretion of two methylated metabolites, N1-methylnicotinamide and N1-methyl-2-pyridone-5-carboxamide, in adults1.
| Both metabolites in urine | What it may mean |
|---|---|
| More than 17.5 µmol a day | Adequate niacin status |
| 5.8–17.5 µmol a day | Low niacin status |
| Less than 5.8 µmol a day | Deficient niacin status |
Labs use different units and ranges. Your clinician reads a result alongside your history and other tests.
Niacin comes in multivitamins, B-complex and niacin-only supplements, and nicotinic acid and nicotinamide are the two most common forms1.
Can cause skin flushing above nutritional needs; some are sold as extended or timed release to lessen it1.
Does not cause flushing and has fewer side effects than nicotinic acid, starting at much higher doses1.
Often labelled flush free; on average about 30% less of its niacin is absorbed1.
A niacin-like compound sold as a supplement but not labelled as a source of niacin1.
Supplements can interact with medicines. Talk to a clinician or pharmacist before you start one, especially at high doses.
Nicotinic acid, one form of niacin in supplements, widens small blood vessels in the skin. The face, arms and chest turn red and can burn, tingle or itch, usually within about 30 minutes. It is considered unpleasant rather than toxic, and nicotinamide does not cause it.
Reference amounts for niacin are given in niacin equivalents (NE), which count both the niacin you eat and the niacin your body can make from tryptophan, an amino acid in protein. Food tables usually list niacin alone, so they understate the total.
Prescription-strength nicotinic acid can improve blood cholesterol and triglyceride levels, but large trials found it did not lower the risk of heart attack or stroke, and it has notable side effects. Experts do not recommend it alongside statins, and very high doses are taken only with medical approval and supervision.
Food logging does not estimate niacin, so Ayuvo tracks it from supplements you log in Medications, and from Apple Health on iPhone or Health Connect on Android when another app saves it there. Charts by day, week, month and year use the reference lines from this page, personalised by age and sex where they differ. Free, with no account.
Or read the code: Ayuvo is open source
Facts on this page come from these sources, checked on the dates shown. Intake numbers come from Ayuvo's shared reference table, which cites the sources marked for them.
General information, not medical advice. This guide is for healthy adults and does not cover pregnancy, breastfeeding, children or medical conditions. It cannot diagnose or treat anything. Talk to a clinician before starting high-dose supplements, or if you think you may have too little or too much of a nutrient. Spotted an error? Email us.