Nicotinamide riboside (NR): what it is and what the research shows

Nicotinamide riboside, usually shortened to NR, is a form of vitamin B3. It has attracted attention because the body can use it to make NAD+, a molecule that every cell needs for many of its chemical reactions.

This article explains what NR is, how the body handles it, and what human trials have found.

What nicotinamide riboside is

NR is made of nicotinamide, one of the forms of vitamin B3, joined to a sugar called ribose. In 2004, researchers showed that cells can use NR to make NAD+ through their own dedicated enzymes, and they reported NR as a nutrient in milk.¹ In cow's milk, NR makes up about 40 percent of the vitamins that serve as building blocks for NAD+.²

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme, a helper molecule that many enzymes need to work. It carries electrons in the reactions that release energy from food, and enzymes such as sirtuins and PARPs, which have several roles inside cells, also depend on it.³

NAD+ and ageing

Research in animals and in human cells shows that NAD+ levels in tissues gradually decline with age, by between 10 and 65 percent depending on the organ and the age.³ In a 2022 study in people, NAD+ was one of the most clearly reduced molecules in the muscle of older adults. It was lowest in older adults with impaired physical function, while older adults who trained regularly had levels close to those of young people.⁴ This is one reason why researchers are testing whether NAD+ building blocks such as NR can help older adults.

How the body handles NR

Inside cells, NR can be converted in two steps into NAD+.¹

Swallowed NR also takes a second route. Research in mice showed that gut bacteria convert much of it into nicotinic acid, another form of vitamin B3, which the body then uses to build NAD+.⁵ A 2026 trial in 65 healthy adults pointed to the same route in people, and found that 1,000 mg of NR a day for 14 days roughly doubled NAD+ in the blood.⁶

The rise is fast and lasting. In an 8-week trial with 140 overweight adults aged 40 to 60, NAD+ in whole blood rose within two weeks by 51 percent at 300 mg a day and by 142 percent at 1,000 mg a day, and stayed at that level until the end of the trial.⁷

What research has looked at

Human trials of NR have so far been small, with between 8 and 140 participants, and have lasted from a single dose to five months. Several of them, carried out in middle-aged and older adults, have reported encouraging results:

• In 24 healthy adults aged 55 to 79, 1,000 mg a day for six weeks raised NAD+ in immune cells by about 60 percent compared with placebo. Blood pressure and the stiffness of the aorta tended to fall. In an exploratory analysis of participants whose blood pressure was above the normal range, systolic blood pressure was about 9 mmHg lower after NR than after placebo.⁸
• In the same group of older adults, NAD+ also rose in tiny particles that nerve cells release into the blood, in nine of the ten participants in whom it could be measured.⁹
• In 12 men with a median age of 75, 1,000 mg a day for three weeks doubled NAAD, a marker of NAD+ metabolism, in muscle, and blood levels of several inflammatory messenger molecules, including interleukin-6, fell.¹⁰
• In a five-month study in identical twins, NR at up to 1,000 mg a day increased the number of mitochondria (the energy-producing structures of cells) in muscle, with about 30 percent more mitochondrial DNA. Muscle stem cells shifted towards forming new muscle fibres, and the gut bacterium Faecalibacterium prausnitzii became more common. Body fat and metabolic health did not improve.¹¹
• In 13 adults with overweight aged 45 to 65, 1,000 mg a day for six weeks increased lean body mass by about 1.3 percent compared with placebo and raised the energy the body used during sleep.¹²
• In older men, a single dose of NR raised NADH, the energy-carrying form of NAD+, by 59 percent and lowered a marker of oxidative stress by 18 percent. Their maximum muscle force in a static test rose by 8 percent and their resistance to muscle fatigue by 15 percent. Young men showed no change.¹³

What the evidence shows overall

One finding is consistent across trials: NR raises NAD+ in the blood, and higher amounts raise it more.^7,8,6 The effects beyond that are still early signals from small trials. Not every trial has found them: a 2025 analysis of trials in adults with an average age over 60 found that NR and a related compound did not change muscle mass or function,¹⁴ and in young, active men, a week of NR did not change how the body used fuel during exercise.¹⁵

Larger and longer trials are under way. One of them is testing 1,000 mg of NR a day for three months on blood pressure and arterial stiffness in adults aged 50 and over with above-normal blood pressure.¹⁶

Safety

NR has been well tolerated in trials. In the 8-week trial with 140 adults, side effects were similar with NR and placebo at up to 1,000 mg a day; there were no serious adverse events and no flushing.⁷ In a 12-week trial in 40 men, 2,000 mg a day caused no serious adverse events, and safety blood tests stayed normal.¹⁷ In the five-month twin study, the side effects reported were mild, such as muscle aches, digestive discomfort, sweating, nausea and headache.¹¹

Open questions

• How much do gut bacteria contribute to the effects of NR?
• Will larger trials confirm the trends seen for blood pressure and arterial stiffness?
• Can NR support muscle and mitochondria in older adults over longer periods, alone or together with exercise?
• Which amounts and durations work best for which outcomes?

Sources

1. Bieganowski P, Brenner C. Discoveries of nicotinamide riboside as a nutrient and conserved NRK genes establish a Preiss-Handler independent route to NAD+ in fungi and humans. Cell. 2004;117:495-502. doi:10.1016/s0092-8674(04)00416-7
2. Trammell SA, et al. Nicotinamide riboside is a major NAD+ precursor vitamin in cow milk. J Nutr. 2016;146:957-963. doi:10.3945/jn.116.230078
3. Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD+ metabolism and its roles in cellular processes during ageing. Nat Rev Mol Cell Biol. 2021;22:119-141. doi:10.1038/s41580-020-00313-x
4. Janssens GE, et al. Healthy aging and muscle function are positively associated with NAD+ abundance in humans. Nat Aging. 2022;2(3):254-263. doi:10.1038/s43587-022-00174-3
5. Chellappa K, et al. NAD precursors cycle between host tissues and the gut microbiome. Cell Metab. 2022;34:1947-1959. doi:10.1016/j.cmet.2022.11.004
6. Christen S, et al. The differential impact of three different NAD+ boosters on circulatory NAD and microbial metabolism in humans. Nat Metab. 2026;8(1):62-73. doi:10.1038/s42255-025-01421-8
7. Conze D, Brenner C, Kruger CL. Safety and metabolism of long-term administration of NIAGEN (nicotinamide riboside chloride) in a randomized, double-blind, placebo-controlled clinical trial of healthy overweight adults. Sci Rep. 2019;9:9772. doi:10.1038/s41598-019-46120-z
8. Martens CR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018;9:1286. doi:10.1038/s41467-018-03421-7
9. Vreones M, et al. Oral nicotinamide riboside raises NAD+ and lowers biomarkers of neurodegenerative pathology in plasma extracellular vesicles enriched for neuronal origin. Aging Cell. 2023;22(1):e13754. doi:10.1111/acel.13754
10. Elhassan YS, et al. Nicotinamide riboside augments the aged human skeletal muscle NAD+ metabolome and induces transcriptomic and anti-inflammatory signatures. Cell Rep. 2019;28(7):1717-1728. doi:10.1016/j.celrep.2019.07.043
11. Lapatto HAK, et al. Nicotinamide riboside improves muscle mitochondrial biogenesis, satellite cell differentiation, and gut microbiota in a twin study. Sci Adv. 2023;9(2):eadd5163. doi:10.1126/sciadv.add5163
12. Remie CME, et al. Nicotinamide riboside supplementation alters body composition and skeletal muscle acetylcarnitine concentrations in healthy obese humans. Am J Clin Nutr. 2020;112:413-426. doi:10.1093/ajcn/nqaa072
13. Dolopikou CF, et al. Acute nicotinamide riboside supplementation improves redox homeostasis and exercise performance in old individuals: a double-blind cross-over study. Eur J Nutr. 2020;59(2):505-515. doi:10.1007/s00394-019-01919-4
14. Prokopidis K, et al. The effect of nicotinamide mononucleotide and riboside on skeletal muscle mass and function: a systematic review and meta-analysis. J Cachexia Sarcopenia Muscle. 2025;16:e13799. doi:10.1002/jcsm.13799
15. Stocks B, et al. Nicotinamide riboside supplementation does not alter whole-body or skeletal muscle metabolic responses to a single bout of endurance exercise. J Physiol. 2021;599:1513-1531. doi:10.1113/JP280825
16. Freeberg KA, et al. Nicotinamide riboside supplementation for treating elevated systolic blood pressure and arterial stiffness in midlife and older adults. Front Cardiovasc Med. 2022;9:881703. doi:10.3389/fcvm.2022.881703
17. Dollerup OL, et al. A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects. Am J Clin Nutr. 2018;108:343-353. doi:10.1093/ajcn/nqy132

This article is for general education about an ingredient and the research on it. It is not medical advice. If you have a health condition, are pregnant or breastfeeding, or take medication, talk to a doctor or pharmacist before taking food supplements.

Last reviewed: October 2026