Nicotinamide Riboside

What it is

Nicotinamide riboside, usually abbreviated NR, is an NAD+ precursor rather than a peptide. It belongs to the vitamin B3 family, alongside niacin, nicotinamide, nicotinamide mononucleotide, and related NAD+ pathway compounds^{[6 –7 ]}. Unlike peptide therapeutics, NR has no amino-acid sequence and is typically sold as an oral supplement ingredient rather than administered as an injectable peptide.

The modern NR field expanded after Bieganowski and Brenner reported in 2004 that NR is a conserved NAD+ precursor and identified nicotinamide riboside kinase pathways involved in converting NR into NAD+^{[8 ]}. That discovery helped place NR into the broader NAD+ salvage pathway, where cells recycle vitamin B3-related molecules to maintain NAD+ pools^{[6 –8 ]}.

NAD+ is involved in redox metabolism and also serves as a consumed substrate for enzymes such as sirtuins, PARPs, and CD38-family enzymes^{[6 –7 ]}. Because NAD+ biology intersects with mitochondrial function, DNA repair signaling, inflammation, and aging-related pathways, NR has been studied as a way to raise NAD+ availability in humans^{[6 –7 ,9 –15 ]}. This biological rationale does not, by itself, prove clinical benefit for longevity, cognition, weight loss, or disease treatment.

When used commercially, NR is typically taken orally as nicotinamide riboside chloride capsules or tablets. Human trials have generally evaluated oral NR or NR combined with other compounds such as pterostilbene^{[9 –18 ]}. These study descriptions are not dosing recommendations.

Regulatory status

Nicotinamide riboside is not FDA-approved as a prescription drug for any indication identified in this review. FDA’s dietary supplement materials explain that the agency does not approve dietary supplements before they are marketed, and manufacturers are responsible for ensuring that products are safe and properly labeled^{[2 –3 ]}.

GRAS and NDI history

NR has a stronger dietary-ingredient regulatory record than many longevity supplements. FDA’s GRAS Notice No. GRN 000635 response stated that the agency had no questions at that time regarding ChromaDex’s conclusion that nicotinamide riboside chloride is generally recognized as safe for specified food uses, while also noting that FDA had not made its own GRAS determination^{[4 ]}. Separately, the FDA NDI framework requires premarket notification for new dietary ingredients unless an exemption applies^{[3 ,5 ]}. Publicly cited NDIN records and peer-reviewed safety publications describe nicotinamide riboside chloride notifications associated with commercial NR products^{[1 ,13 ]}.

This regulatory status should not be confused with drug approval. Dietary supplements may not lawfully be marketed with claims to diagnose, cure, mitigate, treat, or prevent disease unless they meet drug requirements^{[2 –3 ]}. Structure-function claims also require appropriate substantiation and FDA disclaimer language under dietary supplement rules^{[2 –3 ]}.

Compounding pathway

Compounding status is a separate question. NR is not an FDA-approved drug product component identified in this review, and this draft did not identify NR on FDA’s reviewed 503B bulks list or as a shortage-list drug pathway. FDA’s general 503A and 503B materials require compounders to meet specific statutory conditions when using bulk drug substances^{[19 –20 ]}. Injectable or prescription-compounded NR offerings should therefore receive pharmacy-law and FDA-compliance review before any listing or endorsement.

NR is not listed in federal controlled-substance schedules in 21 CFR Part 1308^{[21 ]}. Internationally, EFSA has evaluated nicotinamide riboside chloride as a novel food ingredient and assessed expanded uses, including food-supplement use in adults^{[1 ]}. Date of last regulatory update verification: May 6, 2026.

Research summary

Human NR research is more developed than injectable NAD+ research, but it remains mostly focused on biomarkers, short-term tolerability, and intermediate physiological outcomes. The central reproducible finding is that oral NR can raise blood NAD+ or NAD+-related metabolites in at least some human studies^{[9 –15 ]}. Whether that translates into durable clinical benefit remains less clear.

Bioavailability: Trammell 2016

Trammell and colleagues published one of the key early human bioavailability studies in 2016. In a small human component, oral NR increased blood NAD+ metabolism in a dose-related pattern and supported the view that NR is orally bioavailable in humans^{[9 ]}. This study established pharmacokinetic plausibility but was not designed to test disease outcomes, lifespan, or broad “anti-aging” claims.

Healthy older adults: Martens 2018

Martens and colleagues conducted a randomized, double-blind, placebo-controlled crossover trial in healthy middle-aged and older adults^{[11 ]}. Six weeks of NR increased peripheral blood mononuclear cell NAD+ levels and was generally well tolerated. The study also reported exploratory signals in systolic blood pressure and arterial stiffness, but the authors treated those cardiovascular findings as preliminary rather than definitive^{[11 ]}.

Safety in healthy overweight adults: Conze 2019

Conze and colleagues reported a randomized, double-blind, placebo-controlled study in 140 healthy adults with overweight^{[13 ]}. Nicotinamide riboside chloride increased whole-blood NAD+ in a dose-dependent manner over 8 weeks and was reported as well tolerated, with no flushing signal typical of high-dose niacin^{[13 ]}. This trial supports biomarker elevation and short-term tolerability, not disease treatment.

Insulin resistance and obesity: Dollerup 2018, Remie 2020

Metabolic trials in obesity and insulin resistance have been less supportive. Dollerup and colleagues studied obese insulin-resistant men in a 12-week randomized placebo-controlled trial and reported that NR did not improve insulin sensitivity or several measures of whole-body glucose metabolism^{[12 ]}. Remie and colleagues studied healthy adults with obesity and reported changes in body composition and skeletal-muscle acetylcarnitine concentrations, but did not establish broad improvements in insulin sensitivity or cardiometabolic disease outcomes^{[14 ]}. These findings limit claims that NR supplementation reliably improves metabolic health in humans.

Acute kidney injury pilot: Simic 2020

NR has also been studied in medically vulnerable groups. Simic and colleagues tested a combination of NR and pterostilbene in hospitalized patients with acute kidney injury and found the regimen was feasible and generally safe in that pilot context^{[15 ]}. Because that study used a combination product, it cannot isolate NR effects.

Parkinson disease: NR-SAFE and methylation studies

Neurological research has become an active area. The NR-SAFE study investigated high-dose NR in Parkinson disease and reported safety and tolerability signals, increased blood NAD metabolome markers, and exploratory clinical measures^{[16 ]}. A related Parkinson disease study examined methylation-related safety concerns and did not identify detrimental methylation changes over the study period^{[17 ]}. These trials are early-stage and do not establish NR as a Parkinson disease treatment.

Systematic review: Prokopidis 2025

A 2025 systematic review and meta-analysis examining NR and NMN for skeletal muscle outcomes concluded that current evidence does not support these NAD+ precursors for preserving muscle mass and function in adults over 60 years^{[18 ]}. That finding is important because muscle, frailty, and exercise claims are common in public discussion but remain weakly supported.

Overall, oral NR has reasonable evidence for raising NAD+ biomarkers and short-term tolerability in selected populations. Evidence is not yet sufficient to claim that NR extends lifespan, reverses aging, treats diabetes, prevents dementia, improves Parkinson disease outcomes, or substitutes for established medical care.

Public discourse

Andrew Huberman, PhD, neuroscientist and host of the Huberman Lab podcast, discussed NR and NMN as NAD+ precursors, while distinguishing animal-data enthusiasm from proven human longevity outcomes^{[22 ]}.

Peter Attia, MD, longevity-focused physician and host of The Peter Attia Drive, reviewed NAD+ biology and NR/NMN claims with caution, emphasizing the gap between biomarker changes and clinically proven human outcomes^{[23 ]}.

Charles Brenner, PhD, biochemist who first reported the NR kinase pathway, has been commercially involved in the NR field and argues that NR is a distinct NAD+ precursor while objecting to overbroad anti-aging marketing claims^{[24 ]}.

Eric Verdin, MD, geroscientist and CEO of the Buck Institute for Research on Aging, discussed NAD+ biology, sirtuins, NR, NMN, and skepticism about direct NAD+ IV administration. His comments favor NAD+ precursor biology over unproven infusion claims^{[25 ]}.

Public discourse reflects the views of the speakers cited and does not represent medical advice or the editorial position of ProPeptideGuide.

Side effects and safety

Oral NR has generally been well tolerated in short-term human trials, but the safety database remains smaller than for approved drugs. Trials have usually lasted weeks to a few months and enrolled selected adults rather than broad, medically complex populations^{[9 –18 ]}.

Reported tolerability in trials

In the 140-person Conze trial, nicotinamide riboside chloride was reported as safe and well tolerated over 8 weeks, with dose-dependent NAD+ increases and no flushing signal like that seen with niacin^{[13 ]}. Martens and colleagues also reported tolerability in healthy middle-aged and older adults over 6 weeks^{[11 ]}. Parkinson disease NR studies have examined higher-dose exposure, but those trials remain relatively small and disease-specific^{[16 –17 ]}.

Commonly discussed tolerability issues in the broader NR literature include gastrointestinal symptoms, fatigue, headache, nausea, and nonspecific discomfort, though rates vary by trial and product. Published trials have not established a consistent serious adverse-event pattern attributable to NR, but they are underpowered for rare events^{[9 –18 ]}.

Theoretical and mechanism-based concerns

Theoretical concerns include effects on NAD+-dependent cancer biology, methylation pathways, homocysteine metabolism, immune signaling, and interactions with other metabolic drugs or supplements^{[6 –7 ,17 ]}. These are biologically plausible areas for study, not proven clinical harms. People with active cancer, pregnancy, severe kidney or liver disease, or complex neurological illness were not well represented in most NR trials.

Drug interactions and long-term exposure

Drug-interaction data are limited. Trials have not adequately tested NR with chemotherapy, immunosuppressants, diabetes medications, anticoagulants, Parkinson disease medication regimens, rapamycin, metformin, resveratrol, NMN, or NAD+ injections. Long-term safety data beyond short controlled trials are limited.

Available through

NR is generally available in the United States as an oral dietary supplement ingredient, not as an FDA-approved prescription peptide or drug. FDA does not pre-approve dietary supplements for safety or effectiveness, so product availability does not mean FDA has reviewed a specific product’s clinical claims^{[2 –3 ]}.

No supplement brand, clinic, or telehealth platform is listed for NR as of 2026-05-06. Any future listing should require editorial and legal review of ingredient identity, NDI/GRAS status, label claims, third-party testing, manufacturing quality, adverse-event reporting procedures, and conflict-of-interest disclosures.

ProPeptideGuide does not link to or endorse grey-market vendors, research-chemical suppliers, injectable NR products, or NR products marketed with unapproved disease-treatment claims.