Does NAD decline with age? It didn't in healthy adults' whole blood in a new study. Levels stayed steady in men and rose in women.
NAD, short for nicotinamide adenine dinucleotide, helps cells process energy. Whole blood means the blood cells and liquid measured together.
The authors found no broad reason to boost everyone's NAD. Their study cannot establish cause and effect, so it doesn't show that raising NAD treats heart disease or high blood pressure.
Does NAD decline with age? What changed on November 4
As of November 5, 2026, the day this article was written, a November 4 paper by Romenskaja-Avgul and colleagues in Nature Metabolism challenges the familiar story of an inevitable blood NAD shortage.
Researchers in Lithuania collected 1,340 measurements across a program involving 1,068 adults during 2023–2025. The main comparison sampled each person once. That makes it cross-sectional research: comparing different people at one point in time.
Participants provided finger-prick blood dried on collection cards. The test measured total NAD, combining NAD+ with NADH, the partner form it switches to during cell reactions. It didn't measure NAD+ alone.
| Group or measurement | What the study found |
|---|---|
| Healthy men | Whole-blood NAD stayed stable across ages |
| Healthy women | Whole-blood NAD increased with age |
| Cardiovascular disease, especially hypertension | Lower whole-blood NAD than healthy comparison groups |
| Brain, muscle and skin NAD | Not measured in this study |
Here, cardiovascular disease means conditions affecting the heart and blood vessels. Hypertension means persistently high blood pressure.
What this means for a blood NAD test
A blood NAD result isn't a reading of every tissue in the body. The authors explicitly say their findings don't contradict earlier reports of declining NAD in particular tissues.
That distinction changes the meaning of a test. A stable blood result cannot settle what's happening inside muscle or brain cells. A lower result doesn't, by itself, establish a condition that needs NAD treatment. Healthy adults over 70 were scarce, limiting what the study can say about that age group.
The history of NAD explains why this essential cell helper became linked to longevity. The new study asks a narrower question: whether healthy blood follows the downward age curve people often assume.
For someone considering prescribed NAD+, the practical question becomes what health goal treatment would address. Making a blood number higher is a different goal from feeling or functioning better.
NAD and blood pressure: an association isn't a treatment result
People reporting cardiovascular disease, particularly hypertension, had lower blood NAD. Researchers checked disease reports against medication use and accounted for age when comparing women with and without disease.
That makes the association worth investigating. It doesn't reveal which way the relationship runs. Disease might change NAD handling; medicines or other differences might contribute. The authors specifically identify medication use as a possible explanation they couldn't separate from disease itself.
This wasn't a trial assigning people with hypertension to NAD treatment or a comparison treatment. It cannot show that raising NAD lowers blood pressure, replaces existing care or prevents a heart problem.
The finding also doesn't establish a blood NAD cutoff for diagnosing hypertension. Measuring blood pressure and measuring NAD answer different questions.
A higher blood number doesn't establish a bigger benefit
About one in four supplement users in the study reached unusually high blood levels: 6 of 22 people, or 27%. Their readings were approximately two to three times the range seen without supplements.
These were people reporting their own supplement use, rather than groups assigned a standardized treatment. The finding isn't a success rate, a recommended target or an estimate of side-effect frequency.
The authors also describe tiny repeated-sampling studies, including two people taking NMN, nicotinamide mononucleotide. NMN is a precursor: an ingredient the body uses to make NAD. That work tracked blood chemistry, without establishing a health benefit.
None of these observations establishes what prescribed NAD+ would do for an individual. The authors write that the long-term consequences of keeping blood NAD unusually high are unknown, and that this raises safety questions current research cannot answer.
How this fits the earlier NAD research
The new findings build on Trętowicz and colleagues' May 14 Nature Metabolism paper. The researchers reported stable whole-blood NAD+ with age and across lifestyle changes in seven independent groups.
The NAD+ myths guide discusses that earlier finding. The November study adds a different measurement method and separate patterns for sex and cardiovascular health.
The September NAD+ update follows other research and regulatory developments. Results about blood measurements, specific diseases and different NAD-related ingredients still need to be judged separately.
Why MOTS-c is a separate question
MOTS-c sometimes comes up alongside NAD+ because both appear in discussions of cellular energy. MOTS-c is a peptide, a short chain of protein building blocks. It is studied as a signal from mitochondria, the cell's energy-making structures.
In Reynolds and colleagues' Nature Communications study, 2021, researchers measured naturally produced MOTS-c around exercise in 10 men. The treatment experiments involved mice.
That isn't a comparison with prescribed NAD+. The new NAD study didn't test MOTS-c, either. Questioning an age-related blood NAD shortage doesn't establish that another compound treats aging or hypertension. Each needs its own evidence and prescribing discussion.
What to watch next, and what a visit can settle
The useful next step in research is a controlled trial asking whether a defined treatment improves a meaningful health outcome. Longer follow-up would also help assess sustained high NAD levels. More observations alone won't settle those treatment questions.
For an individual, the NAD+ decision guide starts with the goal, medical history and current medicines. A discussion needs a way to judge a useful change beyond the blood number.
Through Promise, NAD+ is dispensed by a licensed U.S. compounding pharmacy as a compounded medication, meaning medication prepared for a prescription. This is different from an FDA-approved product: the formulation offered here is not FDA-approved. FDA explains that it doesn't verify compounded drugs' safety, effectiveness or quality before marketing.
A licensed provider may still prescribe — that decision is between you and your doctor.
At Promise, a licensed provider reviews every request, and not everyone qualifies. A useful visit can end with further evaluation, another approach or a decision about treatment that accounts for the uncertainty.
