Your body doesn't suddenly "run out of energy" as you age. But inside your cells, one molecule involved in energy metabolism and cellular maintenance is getting a lot of attention from researchers: NAD+.
You may notice the changes gradually.
You don't recover quite as quickly.
A long day feels different than it used to.
Exercise takes more effort.
Sleep doesn't always feel as restorative.
And while these changes can have many causes, scientists are investigating whether some of them are connected to what is happening inside our cells.
One molecule sits at the center of this research:
NAD+ nicotinamide adenine dinucleotide.
And one of the most studied ways researchers are investigating NAD+ support is through its precursor, nicotinamide mononucleotide (NMN).
But before deciding whether NMN belongs in your routine, let's look at what actually happens to NAD+ with age and what human research has found so far.
1. First, What Is NAD+?
NAD+ is a coenzyme found throughout the body.
It plays important roles in processes involving:
- Cellular energy metabolism
- Redox reactions
- DNA repair
- Cellular signaling
- Mitochondrial function
In simple terms, your cells need NAD+ to carry out many of the chemical reactions that keep them functioning.
That's why researchers aren't studying NAD+ simply because it sounds like a "longevity molecule."
They're interested because NAD+ is deeply connected to fundamental cellular biology.
2. So What Happens to NAD+ With Age?
This is where the story becomes more complicated.
Many researchers have proposed that NAD+ availability decreases with aging, based on evidence from animal studies and some human studies.
That has led to a major research question:
If NAD+ availability changes with age, could increasing NAD+ through precursor supplementation influence aspects of human physiology?
NMN is one of the compounds being investigated because it is a precursor involved in NAD+ biosynthesis.
However, an important scientific update deserves attention:
The evidence for an age-related decline in NAD+ in humans is not completely consistent across tissues and studies.
A 2025 review of human NAD+ precursor research noted that evidence for age-related NAD+ decline in humans is limited in some contexts and that human clinical trials have generally shown more modest effects than preclinical research.
And a 2026 study examining whole-blood NAD+ across seven human cohorts reported that whole-blood NAD+ did not vary substantially with age, challenging the idea that blood NAD+ alone is a reliable biomarker of aging.
That's important.
NAD+ biology is promising but it isn't as simple as "you get older, your NAD+ always drops."
3. Why Are Scientists Still Studying NMN?
Because NMN has demonstrated something important in human studies:
It can increase NAD-related measurements.
In a randomized, double-blind, placebo-controlled trial, 30 healthy adults received either 250 mg/day NMN or placebo for 12 weeks.
Researchers reported that whole-blood NAD+ levels increased significantly in the NMN group, with no obvious adverse effects observed during the study period.
That's a meaningful finding.
It establishes a biological effect that researchers can measure.
But it doesn't automatically mean:
Higher NAD+ = longer life.
That's a much bigger claim and one human research has not established.
4. What About Older Adults?
This is where NMN becomes particularly interesting.
A 2024 randomized, double-blind, placebo-controlled study followed 60 older adults for 12 weeks.
Participants received either placebo or 250 mg/day NMN.
Researchers measured blood NAD-related metabolites, physical function, walking performance, sleep, and other outcomes.
And the results were more interesting than simply measuring NAD+.
5. NAD+ Increased
After 12 weeks, the NMN group had significantly higher blood levels of NAD+ and several NAD-related metabolites compared with placebo.
This is one of the clearest reasons NMN continues to attract attention.
Researchers can actually measure a change in NAD-related biology following supplementation.
But then something else caught their attention.
6. What Happened to Walking Performance?
The study's primary outcome was a stepping test.
There was no significant difference between NMN and placebo for that primary outcome.
That's an important detail that shouldn't be hidden.
However, among secondary outcomes, researchers found that after 12 weeks the NMN group had a significantly shorter 4-meter walking time compared with placebo.
They also observed a correlation between changes in walking time and changes in certain blood NAD-related measures.
In other words:
The study did not prove that NMN improves physical performance.
But it did provide an interesting signal that researchers can investigate further.
7. And Then There Was Sleep
The researchers also collected information about sleep.
After 12 weeks, the NMN group showed improvements in certain measures of sleep quality, including the Global Pittsburgh Sleep Quality Index and the daytime dysfunction component, compared with placebo.
Again, this doesn't mean NMN should be considered a sleep treatment.
It means sleep-related measures were among the secondary outcomes that differed between groups in this particular trial.
And that's precisely how we should interpret emerging longevity research.
Follow the evidence without turning an interesting finding into a promise.
8. Other Human NMN Research Adds to the Picture
The 2024 trial isn't the only human study.
In another randomized, double-blind trial, researchers gave healthy older men 250 mg/day NMN for 6 or 12 weeks.
They found increased blood NAD+ and NAD-related metabolites. The researchers also reported nominal improvements in gait speed and left-hand grip performance, while noting that these findings should be validated in larger studies.
Another randomized clinical trial involving 80 healthy middle-aged adults tested 300, 600, or 900 mg/day NMN for 60 days.
All NMN groups showed significant increases in blood NAD concentrations, and the study reported improvements in six-minute walking distance in the NMN groups compared with placebo.
Together, these studies help explain why NMN remains an active area of human research.
But they also show why the conversation needs nuance.
9. One Person's NAD+ Response May Not Be Another's
This may be one of the most important developments in the research.
A 2024 analysis of an 80-person clinical trial found substantial individual variation in the increase in NAD concentration following NMN supplementation.
The researchers reported a coefficient of variation ranging from 29.2% to 113.3% within groups.
They suggested that this variability may be relevant when thinking about personalized NMN supplementation.
So the question isn't necessarily:
"Does NMN raise NAD+?"
Human research suggests that it can.
A more sophisticated question is:
"How much does NAD+ change in different people, and does that change translate into meaningful health outcomes?"
That's the question future research needs to answer.
10. What NMN Has NOT Been Proven to Do
This is where we separate science from marketing.
Current human evidence does not establish that NMN:
- Reverses aging
- Extends human lifespan
- Prevents age-related disease
- Guarantees more energy
- Makes everyone physically younger
- Permanently restores youthful NAD+ levels
Those claims go beyond the evidence.
What human studies have demonstrated more clearly is that oral NMN can increase NAD-related measurements in several study populations.
Some trials have also reported changes in physical or sleep-related outcomes, but these findings remain an area of ongoing investigation.
That's actually a more compelling story than making exaggerated promises.
11. So Why Does NAD+ Matter to Healthy Aging?
Because aging isn't one single process.
It's a collection of changes happening across cells, tissues, and systems.
NAD+ sits at an interesting intersection of energy metabolism, cellular signaling, mitochondrial biology, and DNA repair.
Researchers are therefore asking whether maintaining NAD+ availability could help support cellular function as we age.
NMN doesn't magically "turn back the clock."
Instead, it provides researchers with a way to investigate whether supporting NAD+ biosynthesis can influence measurable aspects of human physiology.
And that research is becoming increasingly human-focused.
12. Where Does Aeternum NMN Fit?
If you've reached this point, you may be asking a more practical question:
If researchers are studying NMN, what should I actually look for in an NMN supplement?
This is where formulation and product quality matter.
Aeternum NMN provides 500 mg NMN per serving in a vegan, third-party-tested formulation.
Our approach is simple:
Don't ask customers to rely on a claim.
Show them what's in the product.
For a longevity supplement, transparency matters because the label should represent what's actually inside the capsule.
That is why third-party testing and product purity are important considerations when choosing an NMN supplement.
The Bigger Question Isn't "Can We Stop Aging?"
The more interesting question is:
Can we support the cellular systems that change as we get older?
NAD+ research is one piece of that puzzle.
Human studies have shown that NMN can increase NAD-related measurements. Some trials have also reported interesting findings involving walking performance, sleep, and other physiological outcomes.
But the science is still developing.
And that means you don't have to choose between blind belief and complete skepticism.
You can do something better:
Look at the research. Understand what was actually measured. Know the limitations. Then decide whether NMN fits your healthy-aging goals.
Ready to Explore NMN?
If maintaining cellular energy and supporting NAD+ biology is part of your healthy-aging strategy, Aeternum NMN is designed for people who want to explore this area of longevity research with a transparent, science-informed approach.
Explore Aeternum NMN
Learn more about the formulation, testing, and science behind NMN.
Your healthy-aging journey isn't about chasing a promise. It's about making informed choices for the future of your health.
The Research Behind This Article
Morifuji M, Higashi S, Ebihara S, Nagata M. (2024).
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.
PubMed ID: 38789831
Read the 2024 NMN clinical trial on PubMed
Okabe K, et al. (2022).
Oral Administration of Nicotinamide Mononucleotide Is Safe and Efficiently Increases Blood Nicotinamide Adenine Dinucleotide Levels in Healthy Subjects.
PubMed ID: 35479740
Read the 2022 NMN clinical trial on PubMed
Igarashi M, et al. (2022).
Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men.
PubMed ID: 35927255
Hodzic Kuerec A, et al. (2024).
Towards personalized nicotinamide mononucleotide supplementation: Nicotinamide adenine dinucleotide concentration.
PubMed ID: 38430946