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NAD+ (Nicotinamide Adenine Dinucleotide)

Evidence Level
Preliminary
6 Clinical Trials
5 Documented Benefits
1/5 Evidence Score

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme every cell uses to carry electrons in energy metabolism and to feed enzymes that repair DNA and run cell signaling. It is sold in capsules, but NAD+ is a large, charged molecule that gut and liver enzymes largely break down, so most of a swallowed dose is not absorbed intact. For that reason, most products that raise NAD+ actually deliver precursors the body assembles into NAD+: NMN, nicotinamide riboside, niacin and niacinamide, each covered on its own page. Controlled trials of those precursors reliably raise NAD+ in the blood, but clinical outcomes in people are still thin and mixed. Intravenous NAD+ is a clinic drip, not an oral supplement, and a drip has not been shown to match any oral benefit. NAD+ levels fall with age in laboratory studies, but whether raising it changes aging in people is unsettled.

Studied Dose No oral dose of NAD+ itself has an established human dose. Products that raise NAD+ usually supply precursors: nicotinamide riboside 100 to 1,000 mg/day and NMN 250 to 900 mg/day in trials. Clinic intravenous NAD+ infusions have used about 3 micromoles per minute over several hours.
Active Compound Nicotinamide adenine dinucleotide (NAD+); its reduced partner is NADH.

Benefits

Coenzyme in energy metabolism and cellular repair

NAD+ carries electrons in the reactions that turn food into cellular energy (ATP), and it is used up by enzymes that repair DNA and run cell signaling. This is an essential housekeeping role present in every cell. Getting enough niacin or another form of vitamin B3 keeps NAD+ supplied; extra beyond what the body needs has not been shown to raise energy in people who are not deficient.

Supported by Trial 1, Trial 5

Blood NAD+ levels rise with oral precursors

In placebo-controlled trials, the precursors nicotinamide riboside and NMN raised NAD+ measured in blood: nicotinamide riboside by 22, 51 and 142 percent at 100, 300 and 1,000 mg a day over 8 weeks, and both roughly doubled blood NAD+ at 1,000 mg a day in a 14-day comparison, while plain nicotinamide did not. So far this is a preliminary marker and not proof of a longevity benefit.

Supported by Trial 2, Trial 3

Aerobic capacity in recreational runners

One 6-week trial gave recreational runners the NAD+ precursor NMN at 600 or 1,200 mg a day while they kept training. Oxygen uptake and power at the ventilatory thresholds rose more than with placebo, but peak power and VO2max did not change, and there were only about a dozen runners per group, so the finding needs confirmation.

Supported by Trial 3, Trial 4

Walking speed and physical function in aging research

Trials of NAD+ precursors in older and middle-aged adults have reported better 4-metre walking time, longer 6-minute walking distance and better sleep scores, but the main pre-set outcome often did not differ from placebo, the results are mixed and come from small trials, and a pooled analysis in adults over 60 found no clear gain in muscle mass, grip strength or walking speed.

Supported by Trial 6, Trial 4

Supplies NAD+-dependent enzymes studied in aging

NAD+ is the fuel for sirtuin and PARP enzymes that take part in DNA repair, gene regulation and metabolic signaling, and NAD+ has been reported to fall with age. Most of this work is preliminary animal studies; no human trial has shown that raising NAD+ changes these enzymes, the pace of aging or lifespan.

Supported by Trial 2, Trial 1

Mechanism of action

1

Electron carrier in energy metabolism

NAD+ accepts and donates electrons as it cycles between NAD+ and NADH. This shuttle drives glycolysis, the citric acid cycle and oxidative phosphorylation in mitochondria, the reactions that produce most of a cell's ATP. A related form, NADP, supports biosynthesis and antioxidant defense.

2

Broken down in digestion, rebuilt from precursors

Swallowed NAD+ is a large, charged dinucleotide that gut and liver enzymes cleave into smaller pieces, so little reaches the blood intact. Cells instead rebuild NAD+ from precursors such as nicotinamide riboside, NMN, niacin and niacinamide, which is why those forms are what most supplements and trials actually use.

3

Consumed by sirtuin and PARP enzymes

Besides carrying electrons, NAD+ is used up as a substrate by sirtuins, which remove chemical tags from proteins, and by PARPs, which flag DNA damage for repair. These enzymes are studied in aging research. Supplying more NAD+ feeds them in laboratory models, but this has not been shown to change aging in people.

Clinical trials

1
Intravenous NAD+ Infusion: 6-Hour Pharmacokinetic Pilot
PubMed

Pilot pharmacokinetic study tracking NAD+ and its breakdown products in plasma and urine during and after a 6-hour intravenous NAD+ infusion; several authors were affiliated with an NAD+ infusion clinic and an NAD+ research company (Grant et al. 2019, Front Aging Neurosci).

11 healthy men aged 30 to 55; 8 received the NAD+ infusion and 3 were controls.

At about 3 micromoles per minute, infused NAD+ was taken out of the plasma rapidly, with no measurable rise in plasma NAD+ or its metabolites for the first 2 hours; extra NAD+ and methyl-nicotinamide then appeared in the urine by 6 hours. The study measured where the infused NAD+ went, not any health outcome, and had no oral comparison.

2
NAD+ Precursors Head-to-Head: NR, NMN and Nicotinamide
PubMed

14-day randomized, open-label, placebo-controlled study comparing three NAD+ boosters on blood NAD+; most of the authors were employees of Nestle (Christen et al. 2026, Nat Metab).

65 healthy adults, average age about 35.

Nicotinamide riboside 1 g a day and NMN 1 g a day each roughly doubled whole-blood NAD+ versus placebo, while nicotinamide 0.5 g a day did not (P=0.461). All three were well tolerated. The study measured a blood marker only; no health outcome was tested. Laboratory work suggested gut bacteria convert part of a dose to nicotinic acid.

3
Nicotinamide Riboside Dose-Response Over 8 Weeks
PubMed

8-week randomized, double-blind, placebo-controlled trial of a branded nicotinamide riboside at 100, 300 or 1,000 mg a day; funded by the ingredient maker (Conze et al. 2019, Sci Rep).

140 overweight but otherwise healthy adults, 35 per group.

Whole-blood NAD+ rose 22, 51 and 142 percent at the three doses within 2 weeks and stayed up. There was no flushing, adverse events matched placebo and LDL cholesterol did not rise. No health outcome was tested, so the trial shows the precursor raises the blood marker and is well tolerated.

4
NMN at Three Doses in Middle-Aged Adults
PubMed

60-day randomized, double-blind, placebo-controlled trial of NMN at 300, 600 or 900 mg a day; three authors were employees of chemical companies (Yi et al. 2023, Geroscience).

80 healthy middle-aged adults.

Blood NAD+ rose in all NMN groups, most at 600 and 900 mg a day. Six-minute walking distance and a general health questionnaire improved more than with placebo, while an insulin-resistance measure did not differ between groups. No safety issues were found.

5
Nicotinamide Riboside in Adults Aged 55 to 79
PubMed

6-week randomized, double-blind, placebo-controlled crossover trial of nicotinamide riboside 1,000 mg a day (Martens et al. 2018, Nat Commun).

30 healthy adults aged 55 to 79.

Nicotinamide riboside raised NAD+ in blood immune cells by about 60 percent versus placebo and was well tolerated. Systolic blood pressure and aortic stiffness showed only exploratory trends, larger in people with above-normal baseline pressure, and neither was significant after adjusting for multiple comparisons.

6
NMN, Walking Speed and Sleep in Older Adults
PubMed

12-week randomized, double-blind, placebo-controlled trial of NMN 250 mg a day; three of the four authors were employees of a food company (Morifuji et al. 2024, Geroscience).

60 older adults.

The pre-set stepping test did not differ from placebo. Blood NAD+ was higher, 4-metre walking time was shorter, and sleep-quality and daytime-dysfunction scores were better than placebo at 12 weeks. No adverse effects were linked to NMN.

Side effects and drug interactions

Common Potential side effects

Oral NAD+ itself has not been tested in controlled safety trials, so what is known comes from its precursors and from NADH.
In a systematic review of NAD-related supplements (NADH and precursors), the products were generally well tolerated, with mild effects that included muscle aches, restlessness, tiredness, sleep disturbance and headache and no serious events.
Pooled analyses of nicotinamide riboside and NMN trials (up to 1,000 to 2,000 mg a day for up to 24 weeks) found adverse events similar to placebo and no rise in liver enzymes; long-term safety beyond about 6 months is untested.
The nicotinic acid (niacin) route to NAD+ causes skin flushing at gram doses and the niacinamide route can stress the liver at gram doses, so those forms have their own cautions; see the niacin and niacinamide pages.
Safety in pregnancy and breastfeeding has not been established; ask a doctor first.

Important Drug interactions

Interactions with oral NAD+ have not been studied in people, and most precursor trials enrolled healthy volunteers rather than people on regular medicines.
Isoniazid (a tuberculosis drug): it interferes with the conversion of niacin to NAD, so combining it with vitamin B3 forms should be discussed with a doctor.
People taking prescription medicines, or who are pregnant or breastfeeding, should ask a doctor or pharmacist before use.

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Frequently asked questions about NAD+ (Nicotinamide Adenine Dinucleotide)

Do NAD+ pills actually raise NAD+?

Not the way the label implies. NAD+ is a large, charged molecule that gut and liver enzymes largely break down, so little of a swallowed NAD+ dose reaches the blood intact. What raises NAD+ in trials are the precursors the body builds it from, mainly nicotinamide riboside and NMN, which reliably increase blood NAD+. See those pages, plus niacin and niacinamide.

Is intravenous NAD+ better than a capsule?

Intravenous NAD+ is a clinic procedure, not an oral supplement. A pilot study found that infused NAD+ is cleared from the plasma quickly and shows up partly in the urine, and no trial has shown that a drip delivers a health benefit, let alone one a capsule could match. It is costly and should be done under medical supervision.

NAD+, NMN or NR, which should I take?

All three aim to raise NAD+, but the precursors are what the body actually absorbs and uses. In a 14-day head-to-head study, nicotinamide riboside and NMN each roughly doubled blood NAD+ while plain nicotinamide did not. None has shown a proven long-term health benefit in healthy adults. See the NMN and nicotinamide riboside pages.

Does NAD+ reverse aging?

There is no good evidence for that in people. NAD+ falls with age in laboratory studies, and raising it helps animals in several models, but human trials of NAD+ precursors so far show mainly a higher blood marker with thin, mixed effects on walking, sleep or metabolism. Treat anti-aging marketing with caution.

How much NAD+ do people take?

There is no established oral dose of NAD+ itself. Trials that raised NAD+ used precursors instead: nicotinamide riboside at 100 to 1,000 mg a day and NMN at 250 to 900 mg a day. Follow the product label, and ask a doctor if you are pregnant, breastfeeding or take prescription medicines.

What is NAD+?

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme every cell uses to carry electrons in energy metabolism and to feed enzymes that repair DNA and run cell signaling.

What is NAD+ used for?

NAD+ is researched primarily for Energy. NAD+ carries electrons in the reactions that turn food into cellular energy (ATP), and it is used up by enzymes that repair DNA and run cell signaling. This is an essential housekeeping role present in every cell.

What is the recommended dosage of NAD+?

The clinically studied dose is No oral dose of NAD+ itself has an established human dose. Products that raise NAD+ usually supply precursors: nicotinamide riboside 100 to 1,000 mg/day and NMN 250 to 900 mg/day in trials. Always follow the product label and check with a healthcare provider for personal advice.

Is NAD+ safe, and does it have side effects?

For most healthy adults, NAD+ is well tolerated at studied doses. Reported effects can include: Oral NAD+ itself has not been tested in controlled safety trials, so what is known comes from its precursors and from NADH. In a systematic review of NAD-related supplements (NADH and precursors), the products were generally well tolerated, with mild effects that included muscle… It may also interact with some medications. NAD+ is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does NAD+ interact with any medications?

Possible interactions include: Interactions with oral NAD+ have not been studied in people, and most precursor trials enrolled healthy volunteers rather than people on regular medicines. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for NAD+?

NutraSmarts rates the evidence for NAD+ as Preliminary (1 out of 5). It is backed by 6 clinical trials and 11 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(11 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Grant R, Berg J, Mestayer R, Braidy N, Bennett J, Broom S, Watson J. A Pilot Study Investigating Changes in the Human Plasma and Urine NAD+ Metabolome During a 6 Hour Intravenous Infusion of NAD. Front Aging Neurosci. 2019;11:257. doi: 10.3389/fnagi.2019.00257.PubMedUsed to support: Pilot pharmacokinetic study in 11 healthy men (8 infused, 3 controls): during a 6-hour intravenous NAD+ infusion at about 3 micromoles per minute, NAD+ was cleared from plasma rapidly with no rise in plasma NAD+ or metabolites for the first 2 hours, and extra NAD+ and methyl-nicotinamide appeared in urine by 6 hours. Several authors were affiliated with an NAD+ infusion clinic and research company; no health outcome was measured and there was no oral comparison.
  2. Christen S, Redeuil K, Goulet L, Giner MP, Breton I, Rota R, Frézal A, Nazari A, Van den Abbeele P, Godin JP, Nutten S, Cuenoud B. 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.PubMedUsed to support: 14-day randomized open-label placebo-controlled study in 65 healthy adults: nicotinamide riboside (1 g a day) and NMN (1 g a day) each roughly doubled whole-blood NAD+, while nicotinamide (0.5 g a day) did not (P=0.461). Lab work suggested gut bacteria convert part of a dose to nicotinic acid. No health outcome was tested. Most authors were Nestle employees.
  3. 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(1):9772. doi: 10.1038/s41598-019-46120-z.PubMedUsed to support: 8-week randomized, double-blind, placebo-controlled trial in 140 overweight adults: branded nicotinamide riboside at 100, 300 or 1,000 mg a day raised whole-blood NAD+ by 22, 51 and 142 percent and was well tolerated, with no flushing, adverse events like placebo and no rise in LDL cholesterol. No health outcome was tested. Funded by the ingredient maker.
  4. Yi L, Maier AB, Tao R, Lin Z, Vaidya A, Pendse S, Thasma S, Andhalkar N, Avhad G, Kumbhar V. The efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial. Geroscience. 2023;45(1):29-43. doi: 10.1007/s11357-022-00705-1.PubMedUsed to support: 60-day randomized double-blind placebo-controlled trial in 80 healthy middle-aged adults given placebo or 300, 600 or 900 mg a day NMN: blood NAD+ rose in all NMN groups, most at 600 and 900 mg; six-minute walking distance and SF-36 scores improved more than placebo; an insulin-resistance measure did not differ; no safety issues. Three authors are employees of chemical companies.
  5. Martens CR, Denman BA, Mazzo MR, Armstrong ML, Reisdorph N, McQueen MB, Chonchol M, Seals DR. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD(+) in healthy middle-aged and older adults. Nat Commun. 2018;9(1):1286. doi: 10.1038/s41467-018-03421-7.PubMedUsed to support: Randomized crossover trial in 30 healthy adults aged 55 to 79: nicotinamide riboside 1,000 mg a day for 6 weeks was well tolerated and raised NAD+ in blood immune cells by about 60 percent. Blood-pressure and aortic-stiffness changes were exploratory trends, not significant after correction for multiple comparisons.
  6. Morifuji M, Higashi S, Ebihara S, Nagata M. Ingestion of β-nicotinamide mononucleotide increased blood NAD levels, maintained walking speed, and improved sleep quality in older adults in a double-blind randomized, placebo-controlled study. Geroscience. 2024;46(5):4671-4688. doi: 10.1007/s11357-024-01204-1.PubMedUsed to support: 12-week randomized double-blind placebo-controlled trial of 250 mg a day NMN in 60 older adults: the primary stepping test did not differ; 4-metre walking time, blood NAD+ and sleep-quality scores were better than placebo. No adverse effects linked to NMN. Three of the four authors are employees of a food company.
  7. Liao B, Zhao Y, Wang D, Zhang X, Hao X, Hu M. Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study. J Int Soc Sports Nutr. 2021;18(1):54. doi: 10.1186/s12970-021-00442-4.PubMedUsed to support: 6-week randomized double-blind placebo-controlled trial in 48 recreational runners given 300, 600 or 1,200 mg a day NMN or placebo while training: oxygen uptake and power at ventilatory thresholds rose more at 600 and 1,200 mg a day than placebo; VO2max and peak power did not change; about 12 runners per group.
  8. Prokopidis K, Moriarty F, Bahat G, McLean J, Church DD, Patel HP. 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(3):e13799. doi: 10.1002/jcsm.13799.PubMedUsed to support: Meta-analysis of randomized trials of NAD+ precursors (NMN and nicotinamide riboside) in adults with a mean age over 60: no significant effect on muscle mass, grip strength, gait speed or chair-stand time, and no improvement in knee strength or physical-performance scores in narrative synthesis.
  9. Trammell SA, Schmidt MS, Weidemann BJ, Redpath P, Jaksch F, Dellinger RW, Li Z, Abel ED, Migaud ME, Brenner C. Nicotinamide riboside is uniquely and orally bioavailable in mice and humans. Nat Commun. 2016;7:12948. doi: 10.1038/ncomms12948.PubMedUsed to support: Mouse and human study: in mice, oral nicotinamide riboside raised liver NAD+ more than nicotinic acid or nicotinamide, and in a first human pharmacokinetic trial (12 adults) single doses of 100, 300 and 1,000 mg raised the blood NAD+ metabolome dose-dependently. Shows the body raises NAD+ from an absorbable precursor, not from intact NAD+.
  10. Bhasin S, Seals D, Migaud M, Musi N, Baur JA. Nicotinamide Adenine Dinucleotide in Aging Biology: Potential Applications and Many Unknowns. Endocr Rev. 2023;44(6):1047-1073. doi: 10.1210/endrev/bnad019.PubMedUsed to support: Critical review: NAD+ levels decline across life and have been proposed to contribute to age-related conditions; raising NAD+ with precursors improves many measures in animals, while early human studies show oral precursors can raise blood and tissue NAD+ safely with only modest or preliminary clinical signals. The authors say the clinical pharmacology is incompletely understood and call for adequately powered randomized trials.
  11. Gindri IM, Ferrari G, Pinto LPS, Bicca J, Dos Santos IK, Dallacosta D, Roesler CRM. Evaluation of safety and effectiveness of NAD in different clinical conditions: a systematic review. Am J Physiol Endocrinol Metab. 2024;326(4):E417-E427. doi: 10.1152/ajpendo.00242.2023.PubMedUsed to support: Systematic review of 10 randomized trials (489 participants) of NADH and NAD+ precursors across conditions such as chronic fatigue, older age, Parkinson disease and prediabetes: the supplements were generally well tolerated with mild side effects (muscle aches, restlessness, tiredness, sleep disturbance, headache) and no serious events, while the authors judged clinical benefits still unproven and called for more trials. Two of the seven authors were affiliated with a company (bio meds Pharma); the review bundled NADH with precursors rather than isolating oral NAD+.