Vitamins · 4 min read ·

Vitamin B3: three forms, three different effects

The body can also make niacin from the amino acid tryptophan. Its forms in supplements behave very differently — from skin flushing to fewer skin cancers.

B3

In a nutshell

1What it does and how much you need

Niacin is the collective name for nicotinic acid and nicotinamide. The body turns them into the coenzymes NAD and NADP, which take part in many reactions in cells. A long-term niacin deficiency causes pellagra.1

EFSA recommendation 1.6 mg NE/MJ EFSA recommends 1.6 mg of niacin equivalents (NE) per megajoule of energy, about 6.6 mg per 1,000 kcal. Tryptophan counts too: from 60 mg of tryptophan the body makes 1 mg of niacin.1

A lack of iron, riboflavin or vitamin B6 slows the conversion of tryptophan to niacin.1

2Where to find it

Data 14 mg A hundred grams of roasted peanuts contain 14 mg of niacin, roasted chicken breast 14 mg, beef liver 13 mg, tuna in oil 12 mg and raw turkey breast 10 mg. 23–70% of it is absorbed — least from cereals, most from animal foods.1,3

3Three forms in supplements

In the EU, supplements may contain niacin as nicotinic acid, nicotinamide, inositol hexanicotinate or nicotinamide riboside chloride.4

Upper level 10 / 900 mg The upper level is only 10 mg a day for nicotinic acid and 900 mg for nicotinamide.2 At higher doses, nicotinic acid widens blood vessels in the skin, which turns red — this is called a flush. The body gets used to the flushing over time.5
Moderate evidence — a review 33 studies Nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are sold as anti-ageing supplements. A review of 33 human studies: they reliably raised NAD in the blood and were well tolerated, but their effects on health were mixed and often absent.6
Moderate evidence over 60 A summary of studies in people over 60: neither NMN nor NR improved muscle mass or strength.7

EFSA assessed nicotinamide riboside chloride as safe for healthy adults up to 300 mg a day, and up to 230 mg for pregnant and breastfeeding women.8

4Heart and skin

Strong evidence — Cochrane 23 studies A review of 23 randomised trials with 39,195 people: nicotinic acid (2 g a day on average) did not reduce mortality, heart attacks or strokes. But people were twice as likely to stop taking it because of side effects.9
Moderate evidence — a large randomised trial 25,673 people In the HPS2-THRIVE trial with 25,673 people with vascular disease, niacin added to statins lowered LDL cholesterol and raised HDL, but heart attacks and strokes did not decrease. Instead, serious diabetes complications, infections and bleeding increased.10
Moderate evidence — a randomised trial −23% People who had had at least two skin cancers other than melanoma in the past 5 years took 500 mg of nicotinamide twice a day or placebo for a year. With nicotinamide they had 23% fewer new skin cancers; side effects did not differ from placebo, and the benefit disappeared after stopping.11

The dose in this study (1,000 mg a day) is above the 900 mg upper level — so it belongs under a doctor’s supervision.2,11

What to take from this

Sources

Written on , based on studies available at that date. Newer research may change the conclusions.

  1. EFSA NDA Panel (2014). Scientific Opinion on Dietary Reference Values for niacin. EFSA Journal 12:3759. doi.org/10.2903/j.efsa.2014.3759
  2. EFSA (2025). Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF) and the EFSA Panel on Nutrition (version 11). efsa.europa.eu
  3. USDA ARS (2018). FoodData Central — SR Legacy, niacin per 100 g: peanuts, roasted, unsalted 14.4 mg (FDC 173806), chicken breast, skinless, roasted 13.7 mg (FDC 171477), beef liver, raw 13.2 mg (FDC 169451), tuna in oil, drained 12.4 mg (FDC 173708), turkey breast, raw 9.9 mg (FDC 171098). fdc.nal.usda.gov
  4. Directive 2002/46/EC on food supplements, Annex II — forms of vitamins and minerals permitted in supplements (consolidated version 26 Nov 2025). eur-lex.europa.eu
  5. Kamanna V. S., Ganji S. H., Kashyap M. L. (2009). The mechanism and mitigation of niacin-induced flushing. Int J Clin Pract 63:1369–1377. doi.org/10.1111/j.1742-1241.2009.02099.x
  6. Gallagher C., Emmanuel O. O. (2026). NAD⁺ supplementation for anti-aging and wellness: a PRISMA-guided systematic review of preclinical and clinical evidence. Ageing Res Rev 116:103057. doi.org/10.1016/j.arr.2026.103057
  7. Prokopidis K. et al. (2025). The effect of nicotinamide mononucleotide and riboside on skeletal muscle mass and function: a systematic review and meta-analysis. J Cachexia Sarcopenia Muscle 16:e13799. doi.org/10.1002/jcsm.13799
  8. EFSA NDA Panel (2019). Safety of nicotinamide riboside chloride as a novel food pursuant to Regulation (EU) 2015/2283 and bioavailability of nicotinamide from this source. EFSA Journal 17:e05775. doi.org/10.2903/j.efsa.2019.5775
  9. Schandelmaier S. et al. (2017). Niacin for primary and secondary prevention of cardiovascular events. Cochrane Database Syst Rev CD009744. doi.org/10.1002/14651858.CD009744.pub2
  10. HPS2-THRIVE Collaborative Group, Landray M. J. et al. (2014). Effects of extended-release niacin with laropiprant in high-risk patients. N Engl J Med 371:203–212. doi.org/10.1056/NEJMoa1300955
  11. Chen A. C. et al. (2015). A phase 3 randomized trial of nicotinamide for skin-cancer chemoprevention. N Engl J Med 373:1618–1626. doi.org/10.1056/NEJMoa1506197

This is general information and does not replace a doctor. High doses of niacin can worsen diabetes control — take them only after talking to a doctor.