RCTJadad 0/5RandomizedDouble-BlindPlacebo-Controlled

NMN and Walking Speed: What a 12-Week Trial in Older Adults Really Showed

GeroScienceMay 24, 2024Vol. 46 (5)

Summary

If you've seen nicotinamide mononucleotide (NMN) marketed as an "anti-aging" or "energy" supplement, this 2024 study is one of the more rigorous human trials behind the buzz — and it's worth understanding exactly what it did and didn't find.

Researchers in Japan ran a 12-week, double-blind, randomized, placebo-controlled trial in 60 older adults, split evenly between a group taking 250 mg/day of NMN and a group taking a matching placebo. NMN is a precursor molecule the body converts into NAD+ (nicotinamide adenine dinucleotide), a coenzyme essential for cellular energy production that's known to decline with age. The theory behind NMN supplementation is that boosting NAD+ levels might help offset some effects of aging, including muscle and mobility decline.

The study's primary outcome was a "stepping test" that measures lower-body motor function — and here, NMN showed no significant advantage over placebo at either the 4-week or 12-week mark. That's an important, sobering headline: the trial's main pre-registered goal wasn't met.

However, several secondary measures told a more encouraging story. After 12 weeks, the NMN group had a significantly shorter 4-meter walking time than the placebo group — meaning they walked a short distance faster, a real-world marker doctors use to gauge frailty risk in older adults. NMN also did what it's supposed to do biologically: blood NAD+ levels, along with its breakdown metabolites (2-PY and 4-PY), rose significantly compared to placebo, confirming the supplement was actually being absorbed and metabolized. Notably, the more a person's blood NAD+ rose, the more their walking speed improved — a correlation that lends some biological plausibility to the walking-speed finding rather than it being a fluke.

Sleep quality also improved in the NMN group, with lower ("better") scores on two components of the Pittsburgh Sleep Quality Index (PSQI): daytime dysfunction and the overall global score. No treatment-related adverse effects were reported in either group over the 12 weeks.

This trial adds to a small but growing pile of NMN human research, including an earlier Japanese dose-ranging study in middle-aged adults that linked NAD+ increases to improved 6-minute walk distances. Together they suggest a consistent, modest signal for walking/mobility benefits — though the primary endpoint miss here is a reminder that NMN is not a proven fix for age-related physical decline, just a promising area of ongoing research.

What This Means For You

For supplement shoppers, this study offers cautious, not enthusiastic, support. The dose used — 250 mg/day, taken once daily for 12 weeks — matches what's commonly sold in commercial NMN capsules and powders, which makes this trial more relevant to real-world use than studies using unusual doses or delivery methods. If you're considering NMN, look for products that disclose independent third-party testing for purity and actual NMN content, since supplement quality varies widely and NMN's regulatory status has been in flux (the FDA reversed a 2022 restriction in September 2025 and now treats NMN as a lawful "new dietary ingredient," though products still require proper notification).

Who might benefit most: this trial enrolled healthy older adults, so the walking-speed and sleep findings are most relevant to that population — people already noticing or wanting to guard against age-related slowing, rather than younger adults or athletes chasing performance gains. The 4-meter walking time result is a clinically meaningful metric (it's used in frailty and sarcopenia screening), so a genuine, reproducible effect here would matter for healthy aging and fall-risk prevention.

Who should be cautious: anyone expecting dramatic results should recalibrate — the study's own primary measure of motor function (the stepping test) showed no benefit. Effects, where they occurred, were modest secondary findings, not transformative changes. People on medications, with existing health conditions, or who are pregnant/breastfeeding should talk to a doctor before starting, since NMN long-term safety data in humans remains limited. Given typical NMN product prices (often $30–$60+ per month), treat this as an optional, low-certainty addition to — not a replacement for — proven mobility and sleep interventions like resistance training, walking programs, and sleep hygiene.

Important Considerations

Several limitations temper how far these results should be extrapolated. First, this was a small trial — only 60 participants total, roughly 30 per group — which limits statistical power and increases the chance that secondary findings (walking speed, sleep) could reflect chance or natural variation rather than a true, reliable effect. Second, and most importantly, the study's own pre-registered primary outcome (the stepping test) showed no significant benefit; the positive findings were secondary outcomes, which are more prone to false positives, especially when several secondary measures are tested (a multiple-comparisons issue the paper doesn't clearly address with correction methods).

The Jadad quality assessment for this paper scored notably low (0 out of 5) because, despite being described as randomized and double-blind, the published text doesn't detail the actual randomization method, how blinding was maintained (e.g., identical placebo appearance/taste), or dropout/withdrawal numbers — details needed to fully judge methodological rigor from the available text.

The 12-week duration is also relatively short for judging effects on aging-related outcomes, and it's unclear how results would hold up over months or years, or after stopping supplementation. Participants were a specific older-adult population in Japan; results may not generalize across different ages, ethnicities, baseline health, or diets. Finally, be skeptical of marketing that cites this study to claim NMN "reverses aging" or "boosts energy" broadly — the actual findings were narrower: modest walking-speed and sleep-quality changes, with the primary physical function measure unaffected. Anyone with health conditions or on medication should consult a healthcare provider before use.

Terms Explained

NMN (nicotinamide mononucleotide)A naturally occurring molecule that the body converts into NAD+; sold as an oral supplement marketed for healthy aging.

NAD+ (nicotinamide adenine dinucleotide)A coenzyme found in every cell that's essential for energy production and cellular repair; levels naturally decline with age.

Double-blind, placebo-controlledA study design where neither participants nor researchers know who receives the real treatment versus a fake (placebo) version, reducing bias in results.

Primary vs. secondary outcomeThe primary outcome is the study's main pre-planned measure of success; secondary outcomes are additional measures analyzed but considered less definitive evidence.

4-meter walking timeA standardized test measuring how fast someone walks a short distance, commonly used by clinicians to screen for frailty and mobility decline in older adults.

Stepping testA motor function assessment measuring lower-body coordination and speed, used here as the study's primary physical-function outcome.

PSQI (Pittsburgh Sleep Quality Index)A standard questionnaire used to score sleep quality; lower scores indicate better sleep.

2-PY and 4-PYBreakdown products (metabolites) of NAD+ found in blood; measuring them helps confirm that NAD+ is actively being produced and processed in the body.

New Dietary Ingredient (NDI)An FDA regulatory category requiring supplement makers to notify the agency before marketing an ingredient not previously sold in dietary supplements before 1994.

Intention-to-treat analysisA way of analyzing trial results that includes all randomized participants in their original assigned group, regardless of whether they fully completed the study, to avoid bias.

Technical Study Details

Study Design

Duration12 weeks

RegistrationUMIN-CTR: UMIN000047871

Total Score

JADAD Quality Assessment

/ 5

評価詳細

Randomization

0 / 2

Is the study described as randomized?

Yes+1

Rationale: The abstract explicitly describes the study as \"randomized\" and states participants were \"randomly allocated\" into groups, satisfying the criterion for Q1.

Is the method of randomization described and appropriate?

No-1

Rationale: The abstract states that participants were "randomly allocated" and describes the study as randomized, placebo-controlled, and double-blind, but it does not specify the actual method used to generate the randomization sequence (e.g., computer-generated random numbers, random number table). Without a description of the specific randomization technique, its appropriateness cannot be verified, so per Jadad scale criteria this should be scored "no."

Blinding

0 / 2

Is the study described as double-blind?

Yes+1

Rationale: The abstract explicitly describes the study design as "double-blind," directly satisfying the criterion for this Jadad scale item.

Is the method of blinding described and appropriate?

No-1

Rationale: The abstract states the study was "double-blind" and "placebo-controlled," but it does not describe the actual method used to achieve blinding (e.g., whether the placebo was identical in appearance, taste, smell, or packaging to the NMN capsules/powder). Without a description of how indistinguishability between NMN and placebo was achieved, the appropriateness of the blinding method cannot be confirmed from the available text, so per the Jadad criteria this should be scored "no."

Dropouts/Withdrawals

0 / 1

Is there a description of dropouts and withdrawals?

No0

Rationale: The provided text is only the abstract of the article, and it contains no mention of the number of withdrawals or dropouts per group, nor reasons for any withdrawals. It states "60 participants were randomly allocated into a placebo group or NMN group" and notes "No adverse effects related to test substance consumption were observed," but there is no explicit statement of how many participants withdrew or dropped out from each group, or their reasons, which is required to answer "yes" on the Jadad scale for this item.</rationale> </invoke>

Study Population

Sample Size60

Age Range-

ConditionAge-related decline in physical (walking) function in older adults

Interventions

Nicotinamide mononucleotide (NMN)

Treatment

Dose250 mg/day

Frequencyonce daily

Duration12 weeks

Routeoral

Placebo

Control

Duration12 weeks

Routeoral

Outcomes

Outcome	Type	Effect	p-value
Stepping test	Primary	-	-
4-m walking time	Secondary	-	-Significant
Blood NAD+ level	Secondary	-	-Significant
Blood NAD+ metabolites (N1-methyl-2-pyridone-5-carboxamide [2-PY] and N1-methyl-4-pyridone-3-carboxamide [4-PY])	Secondary	-	-Significant
Sleep quality (Daytime dysfunction and Global PSQI subscales)	Secondary	-	-Significant
Stress	Secondary	-	-

Safety

No adverse effects related to test substance consumption were observed

Conclusion

NMN intake for 12 weeks increased blood NAD+ and NAD+ metabolite levels, was associated with maintenance of walking speed (shorter 4-m walking time) relative to placebo, and improved sleep quality (lower Daytime dysfunction and Global PSQI scores) in older adults, despite no significant difference being observed on the primary stepping test outcome. No adverse effects related to test substance consumption were observed.