NMN

What it is

Nicotinamide mononucleotide, usually abbreviated NMN, is an endogenous intermediate in nicotinamide adenine dinucleotide biosynthesis. It is not a peptide and does not have an amino-acid sequence. Chemically, it is a ribose-phosphate nucleotide containing nicotinamide, and biologically it sits in the NAD+ salvage pathway between nicotinamide and NAD+^{[1 –2 ,7 ]}.

NAD+ is a central redox cofactor and enzyme substrate involved in energy metabolism, DNA repair signaling, circadian biology, and cellular stress responses^{[7 –8 ]}. NAD+ can be made through several pathways, including de novo synthesis from tryptophan, the Preiss-Handler pathway from nicotinic acid, and salvage pathways involving nicotinamide, nicotinamide riboside, and NMN^{[7 –8 ]}. NMN is converted to NAD+ by nicotinamide mononucleotide adenylyltransferase enzymes^{[2 ,7 ]}.

Modern NMN interest comes largely from aging-biology research. Animal studies have repeatedly shown that NAD+ metabolism changes with aging and that NAD+ precursors can alter metabolic or physiological phenotypes in some model systems^{[7 –8 ]}. Human research is more limited. Trials have generally tested oral NMN as a supplement-like intervention, not as an approved drug for a disease indication^{[9 –16 ]}.

When used commercially, NMN is usually sold as an oral dietary supplement in capsules, powders, or tablets. Human clinical trials have used oral NMN, not injectable peptide-style administration^{[9 –16 ]}. These study designs are descriptive and should not be interpreted as dosing recommendations.

Regulatory status

NMN is not FDA-approved as a prescription drug for any indication identified in this review. FDA does not approve dietary supplements before marketing in the same way it approves drugs; dietary supplement firms are responsible for ensuring products are not adulterated or misbranded and that applicable claims are substantiated^{[3 –4 ]}.

The 2022 drug-preclusion position and the 2025 reversal

NMN’s US supplement status changed materially between 2022 and 2025. In 2022, FDA took the position that NMN was excluded from the dietary supplement definition because it had been authorized for investigation as a new drug and substantial clinical investigations had been made public before FDA accepted the relevant supplement-marketing evidence^{[5 –6 ]}. This led to substantial market uncertainty and industry litigation^{[5 –6 ]}.

On September 29, 2025, FDA responded to citizen petitions and revised its interpretation. FDA concluded that NMN is not excluded from the dietary supplement definition under section 201(ff)(3)(B), because evidence showed NMN had been marketed as a dietary supplement in the United States before the relevant new-drug authorization^{[5 –6 ]}. This did not make NMN an FDA-approved drug, and it did not erase other supplement-law requirements.

NDI compliance still applies

For NDI compliance, FDA’s general rule remains that a manufacturer or distributor must submit a new dietary ingredient notification at least 75 days before marketing a supplement containing a new dietary ingredient, unless an exemption applies^{[4 ]}. Regulatory attorneys commenting on the 2025 FDA reversal have emphasized that NMN’s drug-preclusion issue was narrowed, not that all NMN products automatically satisfy NDI, labeling, safety, manufacturing, or claims requirements^{[6 ]}.

Compounding pathway

Compounding status is a separate issue. NMN is not an FDA-approved drug product component identified in this review, and it is not the same substance as NAD or NADH. FDA’s 503A Category 1 list includes nicotinamide adenine dinucleotide and reduced NADH, but not NMN in the listed Category 1 substances reviewed for this draft^{[17 ]}. FDA’s general 503A and 503B rules restrict bulk-drug compounding to substances meeting statutory pathways, including USP/NF monograph status, approved-drug component status, formal bulks-list status, or shortage-list status, depending on the compounding pathway^{[17 –18 ]}.

NMN is not listed in federal controlled-substance schedules in 21 CFR Part 1308^{[19 ]}. International supplement and novel-food rules vary by jurisdiction and were not comprehensively reviewed for this draft. Date of last regulatory update verification: May 6, 2026.

Research summary

Human NMN research is early but no longer absent. The main clinical themes are NAD+ metabolite changes, insulin sensitivity, exercise physiology, older-adult function, arterial stiffness, and short-term safety^{[9 –16 ]}. Across these areas, trials have generally been small, short, and conducted in selected populations. No large outcomes trial has shown that NMN extends human lifespan, prevents age-related disease, or improves mortality.

Single-administration safety and PK: Irie 2020

The first widely cited human safety study was a single-arm trial in 10 healthy Japanese men. Irie and colleagues tested single oral administrations of 100, 250, and 500 mg NMN and monitored clinical parameters and metabolites for 5 hours after each administration^{[9 ]}. The study reported no significant clinical symptoms or vital-sign changes and found dose-dependent increases in nicotinamide metabolites^{[9 ]}. Because it was small, nonrandomized, and short-term, it mainly supports feasibility and short-term tolerability rather than efficacy.

Insulin sensitivity in prediabetic women: Yoshino 2021

The most discussed metabolic trial was Yoshino and colleagues’ 2021 randomized, placebo-controlled study in 25 postmenopausal women with overweight or obesity and prediabetes^{[10 ]}. After 10 weeks, NMN increased insulin-stimulated glucose disposal and skeletal-muscle insulin signaling compared with placebo^{[10 ]}. The trial did not show significant improvements in body weight, body composition, fasting glucose, insulin, hemoglobin A1c, or several lipid measures^{[10 ]}. Charles Brenner later argued that baseline hepatic lipid imbalance weakened the randomization, while Samuel Klein and Mihoko Yoshino responded that muscle insulin sensitivity was identical at baseline and improved after NMN rather than placebo^{[11 –12 ]}.

Exercise and aerobic capacity: Liao 2021

Exercise-related outcomes were studied by Liao and colleagues in a 6-week randomized, double-blind trial of 48 recreational runners undergoing structured training^{[13 ]}. Participants were assigned to placebo or NMN at 300, 600, or 1200 mg/day. The study reported greater improvements in oxygen uptake measures and ventilatory-threshold power in the medium- and high-dose NMN groups compared with placebo, while VO2max and several peak exercise measures did not significantly differ^{[13 ]}. No adverse events were reported during the intervention^{[13 ]}. This study suggests a possible training-related signal, but it does not establish NMN as a general performance enhancer outside the studied population and protocol.

Older-adult muscle and function: Igarashi 2022, Kim 2022

Older-adult studies have produced mixed and generally modest results. Igarashi and colleagues studied 250 mg/day NMN for 6 or 12 weeks in healthy older men in a randomized, placebo-controlled trial^{[14 ]}. NMN increased whole-blood NAD+ and related metabolites and was well tolerated; nominal improvements were seen in gait speed and left grip strength, but the authors stated these findings required validation in larger studies^{[14 ]}. Kim and colleagues randomized 108 older Japanese adults by timing of intake and found interaction signals for five-times sit-to-stand performance and drowsiness, with the afternoon NMN group showing the largest effect sizes^{[15 ]}. These findings are exploratory and not sufficient to support disease or frailty treatment claims.

Multicenter dose-ranging: Yi 2023

Yi and colleagues conducted a multicenter, randomized, double-blind, placebo-controlled dose-ranging study in 80 healthy middle-aged adults assigned to placebo or 300, 600, or 900 mg/day NMN for 60 days^{[16 ]}. The trial reported dose-related increases in blood NAD concentration and assessed safety, walking distance, calculated biological age, HOMA-IR, and SF-36 measures^{[16 ]}. Interpretation is limited by the short duration and reliance on intermediate or exploratory endpoints rather than clinical outcomes.

Arterial stiffness: Katayoshi 2023

Katayoshi and colleagues conducted a 12-week randomized, double-blind trial in 36 healthy middle-aged adults taking 250 mg/day NMN or placebo^{[20 ]}. Serum nicotinamide increased in the NMN group; pulse-wave velocity, a marker related to arterial stiffness, tended to decrease but did not significantly differ between groups^{[20 ]}. The authors reported good tolerability and no adverse events^{[20 ]}.

Systematic reviews

Systematic reviews have been more cautious than consumer marketing. A 2024 review of 8 randomized trials involving 342 mostly non-diabetic middle-aged or older adults found no significant benefit of short-term NMN on fasting glucose, fasting insulin, HbA1c, HOMA-IR, or lipid profile^{[21 ]}. A 2025 systematic review and meta-analysis of NMN and NR for muscle outcomes concluded that current evidence does not support these supplements for preserving muscle mass and function in adults with mean age over 60 years^{[22 ]}.

Overall, NMN reliably appears capable of altering NAD+ metabolite measures in at least some human studies^{[14 ,16 ,20 ]}. Whether those biochemical changes translate into durable clinical benefit remains unsettled. Evidence is currently insufficient for claims that NMN reverses aging, extends lifespan, treats diabetes, prevents dementia, improves cardiovascular outcomes, or substitutes for established medical care.

Public discourse

David Sinclair, PhD, geneticist and Harvard Medical School professor, has discussed NMN as an NAD+ precursor in the context of aging biology and described his personal use while noting individual variability. His statements should be interpreted as public commentary from a researcher with disclosed commercial ties in the NAD+ field, not as clinical guidance^{[23 ]}.

Peter Attia, MD, longevity-focused physician and host of The Peter Attia Drive, reviewed the Yoshino Science trial and distinguished the insulin-sensitivity signal from stronger claims about human life extension. He described himself as skeptical of NMN as a geroprotective intervention pending stronger evidence^{[24 ]}.

Charles Brenner, PhD, biochemist and NAD+ metabolism researcher, criticized the Yoshino trial’s baseline liver-fat imbalance and argued that it undermined confidence in the trial’s randomization. Brenner has public associations with the NR field, which should be considered when interpreting public commentary^{[11 ]}.

Samuel Klein, MD, and Mihoko Yoshino, MD, PhD, the Yoshino trial investigators at Washington University in St. Louis, responded that baseline hepatic triglyceride differences did not negate their primary muscle insulin-sensitivity finding. Their response is part of the peer-reviewed public record around NMN’s most cited metabolic trial^{[12 ]}.

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

Short-term oral NMN has generally been well tolerated in published human trials, but the safety database remains limited by small sample sizes and short follow-up^{[9 –16 ,20 ]}. Most studies enrolled healthy or selected populations, which limits generalization to people with cancer, pregnancy, severe kidney or liver disease, complex cardiometabolic disease, or those taking multiple medications.

Reported tolerability in trials

Irie’s single-administration trial in 10 healthy men reported no significant clinical symptoms after 100, 250, or 500 mg NMN^{[9 ]}. Fukamizu and colleagues studied 1250 mg/day for 4 weeks in 31 healthy adults and reported no severe adverse events or clinically concerning changes in anthropometry, hematology, biochemical tests, urine testing, or body composition^{[25 ]}. Liao’s exercise trial reported no adverse events over 6 weeks, and Igarashi’s older-men trial reported no serious adverse events over 12 weeks^{[13 –14 ]}.

Theoretical and mechanism-based concerns

Theoretical safety concerns are mostly extrapolated from NAD+ biology rather than confirmed clinical harms. NAD+ pathways are involved in DNA repair, inflammation, cellular metabolism, and cancer biology^{[7 –8 ]}. This does not prove that NMN promotes cancer, but it does mean simplistic “more NAD+ is always better” claims are not scientifically justified. Long-term use in people with active malignancy or high cancer risk has not been established as safe in large clinical trials.

Drug interactions and product variability

Drug-interaction data are limited. Published NMN trials were not designed to evaluate interactions with diabetes drugs, chemotherapy, immunosuppressants, anticoagulants, fertility treatments, or other longevity-oriented compounds such as rapamycin, metformin, resveratrol, NR, or NAD+ infusions. Supplements may also vary in purity, identity, and labeling accuracy, which creates risks separate from NMN as a molecule.

Long-term safety unknown

Long-term safety data are limited. Existing human trials typically range from single-dose exposure to 12 weeks, with one 60-day dose-ranging study and several small 12-week studies^{[9 –16 ,20 ,25 ]}. Decades-long safety, reproductive safety, pediatric use, and safety in medically complex patients remain unresolved.

Available through

NMN is generally sold as an oral dietary supplement rather than prescribed as an FDA-approved drug. Because FDA does not approve dietary supplements before marketing, a product’s availability does not mean FDA has reviewed it for safety or effectiveness^{[3 –4 ]}.

No supplement brand, clinic, or telehealth platform is listed for NMN as of 2026-05-06. Any future listing should require editorial and legal review of NDI status, label claims, manufacturing quality, third-party testing, adverse-event reporting procedures, and compliance with FDA dietary supplement rules.

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