NR (Nicotinamide Riboside)

Overview

Nicotinamide riboside (NR) is a form of vitamin B3 that the body can convert into NAD+, a coenzyme used in energy metabolism and DNA repair. NMN, a closely related precursor, has its own [monograph](/ingredients/nmn-nicotinamide-mononucleotide). In human trials, NR raised NAD+ metabolites in the blood at single doses of 100 to 1,000 mg and at up to 3,000 mg a day for four weeks. Trials have measured blood NAD+ far more than anything a person would feel, and the functional results so far are small, short, or null.

What is NR (Nicotinamide Riboside)?

Quick facts

Key takeaways

• In a one-person pilot, a single oral dose of NR raised blood NAD+ metabolites as much as 2.7-fold (Trammell et al., 2016).
• In an eight-week placebo-controlled trial, whole-blood NAD+ rose 22%, 51% and 142% at 100, 300 and 1,000 mg (Conze et al., 2019).
• In a six-week crossover trial of healthy adults aged 55 to 79, NR at 500 mg twice a day was well tolerated and stimulated NAD+ metabolism (Martens et al., 2018).
• In a 14-day open-label trial of 65 healthy adults, NR and NMN raised circulating NAD+ comparably, and nicotinamide did not (Christen et al., 2026).
• In a 12-week pilot in 42 people who completed the study, with amnestic mild cognitive impairment, NR roughly doubled blood NAD+ and did not improve cognitive function (Martens et al., 2026).
• Multi-week trials that stated a daily dose tested 250 mg to 3,000 mg of NR a day (Dellinger et al., 2017, with pterostilbene; Berven et al., 2023), and both six-week crossover trials in healthy adults used 1,000 mg a day (Martens et al., 2018; Remie et al., 2020).
• NIH lists 35 mg a day as the adult upper limit for niacin, and FDA's 2016 response summarizes a company estimate of 180 mg a day for a 60 kg adult. That estimate is not an NIH or FDA limit.

Nicotinamide riboside is a small molecule made of nicotinamide, a form of vitamin B3, joined to a ribose sugar. Cells use it as one raw material for NAD+, the coenzyme that moves electrons in energy metabolism and that enzymes such as PARPs and sirtuins draw on for DNA repair and other jobs. Supplements sell precursors like NR because cells can convert them into NAD+. For background on what NAD+ does, read What is NAD+?.

Here is the number that surprised us most. In a pilot study of one person, blood NAD+ metabolites rose as much as 2.7-fold after a single oral dose of NR (Trammell et al., 2016). The same paper reported that single doses of 100, 300 and 1,000 mg raised the blood NAD+ metabolome in a dose-dependent way. The authors also named nicotinic acid adenine dinucleotide (NAAD), an intermediate that was not thought to lie on the NR route, as a sensitive marker of NAD+ repletion.

The 2016 FDA response to a GRAS notice describes NR chloride as a water-soluble, off-white powder made in two chemical steps. It also reports the maker's stability data: powder stable for up to 11 months at 25°C and 60% relative humidity, and solution stable for up to 83 days at 4°C. Those are the company's data, not an FDA finding.

NIH's niacin fact sheet lists nicotinamide riboside among the "related derivatives" of niacin and says that NR and NMN "are not marketed or labeled as sources of niacin." NR does not appear in the niacin upper-limit table, so no NIH upper limit is listed for it.

How NR gets into the bloodstream, and how fast it clears, is not settled in the sources checked for this page. Trammell et al., 2016 reported that oral NR raised liver NAD+ in mice, with pharmacokinetics the authors described as distinct and superior to those of nicotinic acid and nicotinamide. Mouse liver data do not tell us what a person absorbs.

Two routes are in play. The route most textbooks describe takes NR to NMN and then to NAD+ inside cells. A 2026 trial proposes a second route, in which gut bacteria convert NR and NMN into nicotinic acid, which then feeds NAD+ through the Preiss-Handler pathway (Christen et al., 2026). The authors say the mechanism had not been confirmed in humans, and the gut step came from ex vivo fermentation and whole-blood tests, not direct measurements in people.

How it works

How NR is supposed to work

NAD+ is the working form of a coenzyme that cells use in energy metabolism. Enzymes such as sirtuins and PARPs consume it while they work, so cells have to keep rebuilding the pool. NR is one of the raw materials cells can convert into NAD+. The textbook route runs from NR to NMN and then to NAD+ inside the cell. For the wider picture, see the NAD+ and longevity guide. For a different longevity compound that acts by another route, see urolithin A.

A second route has been proposed. Christen et al., 2026 found that NR and NMN raise circulating NAD+ over 14 days, and that human gut microbiota convert both into nicotinic acid in ex vivo fermentation. The authors propose that nicotinic acid then feeds NAD+ through the Preiss-Handler pathway. The gut step came from ex vivo fermentation and whole-blood tests, not from direct measurements in people, so treat it as a model.

What the trials can test is the first link in the chain: does more NR in the blood raise NAD+ metabolites in cells? In healthy and older adults, it did in every randomized trial we checked that measured it. The next link, whether a higher NAD+ pool changes a function a person would notice, is where the evidence thins out. Brakedal et al., 2022 is one example. NR raised cerebral NAD+ in people with Parkinson's disease in a significant but variable way, and the participants with the biggest rises showed altered brain metabolism and mild clinical improvement. That is a signal worth following up. It is not a demonstration that NR changes the disease.

Evidence at a glance

Grades follow the site's scale. Strong means several human randomized trials with a consistent direction. Moderate means at least one well-run human RCT, or consistent trials with clear limits. Preliminary means small human trials. Insufficient means null or conflicting human data, or animal data only.

NR against NMN

Three things are known. NR and NMN both raise blood NAD+ in people. The NMN trials include Igarashi et al., 2022, 250 mg a day for six or 12 weeks in older men, where NAD+ metabolites rose and gait speed and grip showed nominal gains that the authors want confirmed. Yi et al., 2022 tested 300, 600 and 900 mg a day for 60 days in 80 middle-aged adults, with NAD+ highest at 600 and 900 mg and a longer six-minute walk than placebo at all three doses. Fukamizu et al., 2022 tested 1,250 mg a day for up to four weeks in 31 adults aged 20 to 65 and reported no severe adverse events.

The only trial that compared the two compounds in the same people is Christen et al., 2026. Over 14 days, NR and NMN raised circulating NAD+ comparably, and nicotinamide did not. The trial was company-run, conducted at Nestlé Research's Clinical Innovation Lab in Lausanne, and its open-label design gave 1,000 mg a day of NR or NMN for 14 days to 65 analyzed adults aged 18 to 50. Eleven of its twelve authors list Nestlé affiliations, and the study compared NAD+ and microbial markers, not a function a person would notice. No trial we checked compared NR and NMN on a functional outcome, so the evidence cannot rank them by what a person would feel. Anyone who reads "NMN beats NR" or the reverse is reading more into the data than exists. For the other comparison on this site that involves a precursor, see urolithin A and NMN compared.

What the evidence doesn't support yet

Raising blood NAD+ is not the same as a change you would feel. In the 12-week mild cognitive impairment pilot, blood NAD+ roughly doubled, and the primary cognitive outcome did not improve (Martens et al., 2026). The regional blood-flow increases in the hippocampus were exploratory, and the authors ask for longer treatment durations. In the six-week muscle and body-composition study, insulin sensitivity did not change and the authors describe the body-composition changes as minor (Remie et al., 2020). For the wider cognition evidence, see the brain health guide.

Neuroprotection in Parkinson's is a hypothesis. The Parkinson's trials checked here are small, with 30 people in the 2022 study and 20 in the 2023 safety study. The 2022 authors call for larger trials before any protective claim. The 2023 safety trial tested 3,000 mg a day for four weeks and reported no moderate or severe adverse events, but it was not built to show a clinical benefit.

Blood pressure and arterial stiffness are open questions. The 2018 crossover trial named both as outcomes that larger trials should test, and the 2026 pilot found no blood pressure change over 12 weeks. For the wider blood pressure evidence, see the heart and blood pressure guide.

No human trial we checked measured lifespan, so any lifespan claim for NR in people is untested. Two of three authors of the 2019 eight-week trial list affiliations with the ingredient's manufacturer, which is one more reason to read the company-linked numbers with care.

Related reading

• The NR clock pilot and the 2026 review that scored it
• Trimethylglycine (TMG) and the methyl-cost question
• our full review: every registered NMN, NR and urolithin A trial
• Our full review of who funds the NR trials
• The full table of NR trials that missed their main outcome

Clinical evidence

• Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. — Who and n: 30 healthy middle-aged and older adults randomized, 24 completed; aged 55 to 79. Duration: two 6-week periods, crossover with placebo. Dose: nicotinamide riboside chloride, 500 mg twice a day (1,000 mg a day). Measure: NAD+ metabolism in blood and tolerability. Result: the abstract reports that NR effectively stimulated NAD+ metabolism and was well tolerated; the size of the rise is not stated in the abstract. Limitation: 24 completers; the authors name blood pressure and arterial stiffness as outcomes for larger trials.
• Safety and Metabolism of Long-term Administration of [product name omitted] (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults. — Who and n: overweight but otherwise healthy men and women; n not stated in the abstract. Duration: 8 weeks. Dose: 100, 300 or 1,000 mg NR chloride; daily schedule not stated in the abstract. Measure: whole-blood NAD+ and other NAD+ metabolites, adverse events, LDL cholesterol, one-carbon metabolism. Result: whole-blood NAD+ rose 22%, 51% and 142% at the three doses, dose-dependently and within 2 weeks; no reports of flushing; no significant adverse-event difference from placebo; LDL cholesterol not raised. Limitation: two of three authors list affiliations with the ingredient's manufacturer; n not in the abstract.
• Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD+ levels in humans safely and sustainably: a randomized, double-blind, placebo-controlled study. — Who and n: 120 healthy adults aged 60 to 80, randomized to placebo, NRPT 1X or NRPT 2X. Duration: 8 weeks. Dose: NR 250 mg a day (NRPT 1X) or 500 mg a day (NRPT 2X), each with pterostilbene (50 or 100 mg). Measure: whole-blood NAD+ at baseline, day 30 and day 60; safety. Result: NAD+ rose about 40% (250 mg) and about 90% (500 mg) by day 30 over baseline, and placebo did not change; the 250 mg rise held near 40% at day 60; no serious adverse events. Limitation: company-run (Elysium Health supplied the product, and six of seven authors list it); older adults only; secondary endpoints not powered.
• Nicotinamide riboside supplementation alters body composition and skeletal muscle acetylcarnitine concentrations in healthy obese humans. — Who and n: 13 healthy men and women with overweight or obesity. Duration: 6 weeks per arm, crossover with placebo. Dose: NR 1,000 mg a day. Measure: body composition, muscle acetylcarnitine, insulin sensitivity, mitochondrial function, ambulatory blood pressure. Result: fat-free mass rose 1.34 percentage points over placebo (P = 0.02); muscle acetylcarnitine rose (P = 0.04); insulin sensitivity, mitochondrial function and ambulatory blood pressure did not change. Limitation: 13 participants; the authors call the body-composition changes minor.
• The NADPARK study: A randomized phase I trial of nicotinamide riboside supplementation in Parkinson's disease. — Who and n: 30 newly diagnosed, treatment-naive adults with Parkinson's disease. Duration: 30 days. Dose: 1,000 mg NR or placebo (daily schedule not stated in the abstract). Measure: cerebral NAD+ by magnetic resonance spectroscopy, brain metabolism by FDG-PET, safety. Result: well tolerated; a significant but variable rise in cerebral NAD+; participants with higher brain NAD+ showed altered brain metabolism and mild clinical improvement. Limitation: phase I size; the authors call neuroprotection a possibility that needs larger trials.
• NR-SAFE: a randomized, double-blind safety trial of high dose nicotinamide riboside in Parkinson's disease. — Who and n: 20 people with Parkinson's disease, randomized 1:1 (10 NR, 10 placebo). Duration: 4 weeks. Dose: NR 1,500 mg twice a day (3,000 mg a day). Measure: moderate and severe adverse events (primary), mild adverse events, blood and urine NAD+ metabolome, MDS-UPDRS. Result: no moderate or severe adverse events with NR; no significant difference in mild adverse events; blood NAD+ rose up to 5-fold; the MDS-UPDRS change was associated with time since the last levodopa dose. Limitation: 20 participants over four weeks; a safety design, not an efficacy trial.
• A phase-II randomized controlled pilot study of nicotinamide riboside supplementation in older adults with amnestic mild cognitive impairment. — Who and n: 42 older adults with amnestic mild cognitive impairment completed (22 NR, 20 placebo). Duration: 12 weeks. Dose: not stated in the abstract. Measure: cognitive function (primary), cerebral blood flow and blood pressure (secondary), blood NAD+. Result: blood NAD+ increased twofold in the NR group; no improvement in cognitive function, total cerebral blood flow or blood pressure; exploratory rises in regional blood flow, particularly in the hippocampus. Limitation: pilot design; exploratory regional analyses; no serious adverse effects reported.
• The differential impact of three different NAD boosters on circulatory NAD and microbial metabolism in humans. — Who and n: 65 analyzed healthy adults aged 18 to 50, randomized, open-label, placebo-controlled, run by Nestlé Research. Duration: 14 days. Dose: 1,000 mg a day of NR or NMN (from the full text). Measure: circulating NAD+, whole-blood NAD+ metabolome, microbial metabolism tested ex vivo. Result: NR and NMN, but not nicotinamide, comparably increased circulating NAD+; nicotinamide acutely and transiently changed the whole-blood NAD+ metabolome. Limitation: open-label; eleven of twelve authors list Nestle affiliations; the gut mechanism was tested ex vivo.
• Nicotinamide riboside is uniquely and orally bioavailable in mice and humans. — Who and n: one individual in a pilot study, plus a human dose-finding study (n not stated in the abstract). Duration: single doses. Dose: single oral doses of 100, 300 and 1,000 mg NR. Measure: blood NAD+ metabolome, including nicotinic acid adenine dinucleotide (NAAD). Result: a single dose raised blood NAD+ as much as 2.7-fold in the pilot; the rise was dose-dependent across the three doses. Limitation: single doses only; the abstract describes no placebo arm, so the study-type label is our reading; mouse data are not human data.

Dosage & forms

• Capsules (NR chloride powder):
• Powder (scoop or weighed):
• Multi-ingredient blends with NR as one ingredient:

Safety & interactions

How much to take

The doses the trials tested ranged from 100 mg to 3,000 mg. The six-week crossover trial used 500 mg twice a day, which is 1,000 mg a day, and the six-week study in adults with overweight or obesity used 1,000 mg a day (Martens et al., 2018; Remie et al., 2020). The four-week safety trial used 1,500 mg twice a day (Berven et al., 2023). The eight-week trial tested 100, 300 and 1,000 mg, and its daily schedule is not stated in the abstract (Conze et al., 2019). The eight-week trial of NR combined with pterostilbene gave 250 or 500 mg of NR a day (Dellinger et al., 2017).

We checked three NR products on each brand's own product page on October 19, 2026. Thorne NiaCel 400 lists 415 mg of nicotinamide riboside hydrogen malate per one-capsule serving, taken once a day, and the label does not give the free NR content. Elysium Basis lists 250 mg of NR chloride per two-capsule serving, taken each morning. Tru Niagen 300mg lists 300 mg of NR chloride per one-capsule serving, with one capsule one to three times a day as needed, which comes to 300 to 900 mg a day. None of the three labels reaches 1,000 mg a day at its suggested use, so none matches the dose the six-week trials used. The product this site sells, NMN + NR capsules, provides 200 mg of NR per two-capsule serving, taken once a day. That is below the lowest daily dose in any multi-week trial we checked with a stated schedule.

Timing is not established. The abstracts we checked do not say when in the day the doses were taken. No trial in our evidence table combined NR with NMN or niacin at full doses, so stacking precursors is untested.

Blood NAD+ metabolites rose within two weeks in the eight-week trial and within 14 days in the open-label comparison. The trials that measured function ran six to 12 weeks and did not establish a functional change.

The eight-week trial shows a larger rise at 1,000 mg (142%) than at 300 mg (51%), so blood NAD+ keeps responding across the tested range. Whether more NR helps a function a person would notice is not established at any dose the trials tested.

Normal dose safety

No trial in our evidence table reported a common side effect with a rate. The trials report no flushing in the eight-week study, no significant adverse-event difference from placebo in that study, and no moderate or severe adverse events with NR in the four-week high-dose study (Conze et al., 2019; Berven et al., 2023). The 2026 cognitive pilot reported no serious adverse effects over 12 weeks (Martens et al., 2026). The 2018 crossover trial described NR as well tolerated (Martens et al., 2018).

The safety record is short. The longest trial in our table ran 12 weeks, and the abstracts give no safety data beyond that. A reader who plans a year of use should not assume the short-term record covers it. We could not build a frequency table of side effects (common, uncommon, rare) from the abstracts, so we do not list them by frequency.

Drug interactions

Upper limits

NIH's niacin fact sheet sets an adult upper limit of 35 mg a day for niacin. NR is not in that table, and NIH lists no separate limit for it. The 2016 GRAS notice for NR chloride, as summarized in FDA's response letter, estimated a tolerable intake of 3 mg per kg of body weight a day, or 180 mg for a 60 kg adult. That estimate came from a 90-day rat study with a 100-fold safety factor. It is the company's estimate, and it is not an NIH or FDA limit.

The four-week trial at 3,000 mg a day, well above that estimate, reported no moderate or severe adverse events. Short trials cannot settle a long-term limit, and no trial in our table ran longer than 12 weeks.

Who should ask first

Ask your prescriber before you start if any of these apply to you:

• Pregnancy or breastfeeding. The abstracts we checked report no pregnancy or nursing data.
• Children. None of the abstracts in our table describes children as participants.
• Any prescription medicine, especially levodopa or other Parkinson's treatments.
• Cancer treatment. No trial in our table studied people in cancer treatment.
• Kidney or liver disease. No trial in our table studied those conditions.

Signs of taking too much

The trials we checked report no flushing and no serious adverse events at the doses tested. None of the abstracts describes a toxicity threshold. If new symptoms appear after you start, stop and call your prescriber.

Ask your prescriber before you start, and tell them the milligrams of NR per day you plan to take.

Buying guide

What dose to look for

The multi-week trials that stated a daily dose tested 250 mg to 3,000 mg a day. A dose below 250 mg a day is a choice none of those trials tested, and the trials cannot tell you whether it works. Read the milligrams of NR per serving and the number of servings a day, then do the arithmetic yourself. The NMN and NR buying guide ranks the labels in this category, and this page explains the numbers behind that ranking.

Form

Look for nicotinamide riboside chloride on the label. That is the salt named in the trial methods and in the FDA's 2016 GRAS response. A label that says only "NR" or "nicotinamide riboside", with no salt named, leaves the form open.

Testing and the certificate of analysis

Ask for a certificate of analysis for the lot you bought, and check that the lot number matches the bottle. Look at identity and purity results, and ask which lab ran them. The 2016 GRAS notice lists the maker's own specifications for NR, including purity of 95 to 102% and limits for arsenic, mercury and lead. Those are the maker's specifications, not an independent test, so they tell you what to ask for rather than what a given lot contains.

Price per day

Divide the price by the number of days the bottle lasts at the label's dose, then compare price per day with the milligrams of NR per day. A bottle that costs more and delivers the same milligrams is not a better deal.

Red flags

• A proprietary blend that hides the NR amount.
• "Clinically proven" claims with no named trial.
• Doses far below or far above the trial amounts, with no reason given.
• No certificate of analysis for the lot you are buying.

Where our product stands

We sell an NMN + NR capsule with 200 mg of NR per two-capsule serving, and a 60-capsule bottle holds 30 servings. The product page lists $59.99 as of October 19, 2026, which is $2.00 a day at one serving. At 200 mg, the dose is below the 1,000 mg a day used in the six-week trials and below the 3,000 mg a day used in the four-week safety trial. It is also above the 180 mg a day company estimate in the upper-limits section. So it does not match the trial doses, and it does not match that estimate. The product page says ISO 17025-accredited labs check the results, that a certificate of analysis is available for every lot, and that the product is made and tested in Mt. Angel, Oregon. Those are the brand's own statements. The lab-testing page lists the certificates by product and lot.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

The bottom line

NR raises blood NAD+ in human trials, and the functional results so far are small, short or null. If you want to try it, pick a label with a stated NR amount per serving, a named salt, and a lot-level certificate of analysis. Compare the milligrams with the trial doses before you pay, and ask your prescriber first if you take any medicine.

Related reading

• How NR got from a 2016 pharmacokinetic study to a 2018 trial
• What the trials show for resveratrol in NMN and NR blends
• NMN vs NR: which precursor to take, and what the trials cannot say
• What a black pepper extract (Bioperine) line means for NR labels
• the niacin history behind NR
• what the human NR trials recorded about side effects and labs

Frequently Asked Questions

What is NR, and how does it become NAD+ inside a cell?

NR is a vitamin B3 compound made of nicotinamide joined to a ribose sugar. Cells use it as a raw material for NAD+, a coenzyme that carries electrons in energy metabolism and that enzymes such as PARPs and sirtuins use for DNA repair and other jobs. The route most textbooks describe turns NR into NMN and then into NAD+ inside the cell. A 2026 human trial proposes a second route, in which gut bacteria turn NR and NMN into nicotinic acid that then feeds NAD+ through the Preiss-Handler pathway. The authors call that a proposed model, not a confirmed mechanism.

What did the human trials measure, at what doses, and for how long?

Most trials measured blood NAD+ metabolites rather than how people feel. A single-dose study in 2016 used 100, 300 and 1,000 mg and found a dose-dependent rise, with a 2.7-fold peak in one pilot participant. An eight-week placebo-controlled trial used 100, 300 and 1,000 mg and found whole-blood NAD+ up 22%, 51% and 142%. A six-week crossover trial used 1,000 mg a day in healthy adults aged 55 to 79. The functional studies ran six to 12 weeks, and a 12-week pilot in people with mild cognitive impairment did not improve cognition.

How does the NR evidence compare with the NMN evidence, in one honest paragraph?

The two compounds have similar evidence for raising blood NAD+ in people. The NMN human trials include a 60-day trial of 300, 600 and 900 mg a day in 80 middle-aged adults, and a six- or 12-week study of 250 mg a day in older men. The NR trials include six weeks at 1,000 mg a day and a 2026 comparison. The only trial that tested both in the same people was a 14-day open-label study of 65 adults, where NR and NMN raised circulating NAD+ comparably. No trial we checked compared them on a function a person would notice, so the evidence does not rank them.

What is NR's regulatory status as a US dietary ingredient, and what is the primary source for that status?

We confirmed one primary FDA source: FDA's 2016 response to GRAS notice GRN 000635. It said FDA had no questions about NR chloride as a source of vitamin B3 in specified foods such as vitamin waters and nutrition bars, and it said FDA had not made its own GRAS determination. We did not confirm NR's status as a dietary ingredient for supplements from an FDA source, so this page does not state that status. Check FDA's new dietary ingredient records before you rely on any claim about supplement status.

What side effects and interactions were reported, and who should ask a clinician first?

The trials checked report no flushing in an eight-week study at 100 to 1,000 mg, no significant adverse-event difference from placebo in that study, and no moderate or severe adverse events in a four-week study at 3,000 mg a day. Short trials cannot show long-term safety. Ask a clinician first if you are pregnant or breastfeeding, if you take any prescription medicine (levodopa in particular), or if you are in cancer treatment or have kidney or liver disease, because none of the trials in our table studied those groups.

What should a buyer check on an NR label: the form, the amount per serving, and the testing?

Check three things. First, the form: nicotinamide riboside chloride should be named on the label. Second, the amount per serving, in milligrams, and the number of servings a day, so you can compare it with the 1,000 mg a day used in the six-week trials. Third, testing: ask for a certificate of analysis for the lot you bought, with a matching lot number and the laboratory named. A label with a proprietary blend that hides the NR amount cannot be checked against any trial.

How does a 200 mg daily dose compare with the doses tested in trials?

Trials used 1,000 mg a day for six weeks, 1,500 mg twice a day for four weeks, 250 or 500 mg a day with pterostilbene for eight weeks, and 100, 300 and 1,000 mg in an eight-week study whose daily schedule the abstract does not state. A daily dose of 200 mg is below every multi-week daily dose we verified with a stated schedule, and the lowest of those was 250 mg. The eight-week study tested 100 mg in one arm, but its schedule is not stated in the abstract. A lower dose does not necessarily do nothing. It means the trials cannot tell you what it does.

Does NR cause the flushing that niacin causes?

Nicotinic acid, the niacin form, causes skin flushing at supplement amounts beyond nutritional needs, according to NIH's niacin fact sheet. The eight-week NR trial reported no flushing at 100, 300 or 1,000 mg. That is a trial result, not a guarantee, because the trial was small and short, and some people may react differently. If you notice flushing or another new symptom, stop and call your prescriber.

Do I need NR at all?

Probably not, unless a clinician who knows your history agrees. NR raises blood NAD+ in trials, but the trials checked here did not show a change in cognition, insulin sensitivity or blood pressure that a person would notice. Nothing in those trials makes NR a necessary part of a supplement routine. If you still want to try it, the buying section explains what to check on the label, and the safety section lists who should ask first.