NAD+ Supplement: Evidence, Effects & What to Measure | YEARS
NAD+ is ubiquitous. In longevity forums, the daily routines of tech CEOs, and the aisles of supplement providers, the molecule is touted as a key to cellular energy, repair, and a healthier life…
NAD+ is Everywhere: Separating Scientific Evidence from Marketing Hype
NAD+ is ubiquitous. In longevity forums, the daily routines of tech CEOs, and the aisles of supplement providers, the molecule is touted as a key to cellular energy, repair, and a healthier life. The promises are vast: slowed aging, a sharper mind, and an optimized metabolism. But what is actually backed by science, and what is purely marketing hype?
Many people reach for an NAD+ supplement, such as NMN or NR, hoping for a quick effect without knowing their physiological baseline. They invest in a molecule whose benefits for hard clinical endpoints—like preventing heart attacks or adding healthy life years—remain unproven in humans.
This article provides a clinically grounded perspective. We analyze the human studies, explain the differences between the available precursors, and show you why comprehensive diagnostics should be the first and most important step long before you take your first capsule. True prevention begins with data, not guesswork.
What is NAD+ and Why is it Central to Aging Research?
Nicotinamide adenine dinucleotide, or NAD+, is one of the most critical molecules in the human body. Every cell requires it for fundamental metabolic processes. As a coenzyme, it catalyzes countless reactions that are essential for our survival.
The Dual Role: Energy Production and Cellular Repair
Two of its primary functions are particularly relevant to the biology of aging:
- Energy Production: Within the mitochondria, NAD+ is crucial for converting the food you eat into cellular energy (ATP). Without sufficient NAD+, this process runs inefficiently.
- Cellular and DNA Repair: NAD+ serves as the fuel for two vital enzyme families:
- Sirtuins: These proteins regulate DNA repair, inflammation, and metabolism, consuming NAD+ in the process. - PARPs (Poly-ADP-ribose polymerases): These enzymes repair DNA damage and also consume NAD+ to function.
The Age-Related Decline: Fact or Myth?
The central argument for taking an NAD+ supplement is the observation that NAD+ levels decline with age. Preclinical studies in cell cultures and animal models show this quite consistently. In humans, however, the data is more nuanced. Measurements point to age-related declines in certain tissues, but the exact extent varies heavily depending on the measurement method, individual health status, and study design (Covarrubias et al., 2021; Vinten et al., 2025).
This potential decline could occur because cells produce less NAD+, while consumption increases due to chronic inflammation or accumulated DNA damage. However, this mechanism does not automatically mean that oral supplementation will yield relevant clinical benefits in humans.
NAD+ IV Therapy: The "Detox" Myth and Clinical Reality
Alongside oral supplements, high-dose NAD+ IV therapies are increasingly heavily promoted, often under the guise of a "detox" or "anti-aging treatment." Providers promise rapid effects such as boosted energy, mental clarity, or relief from withdrawal symptoms.
The evidence base for this is extremely thin. There are no robust, placebo-controlled human trials that support these sweeping marketing claims. In this context, the term "detox" is medically misleading and lacks any scientific foundation.
For this reason, YEARS does not offer NAD+ infusions. We focus on evidence-based diagnostics and interventions whose safety and utility have been evaluated in clinical studies. An infusion without a clear medical indication and proven efficacy does not align with our clinical standards.
NMN vs. NR: Comparing the Main NAD+ Precursors
If you are looking for an oral NAD+ supplement, you will usually encounter two acronyms: NMN (Nicotinamide Mononucleotide) and NR (Nicotinamide Riboside). Both are precursors that the body can use to synthesize NAD+. Ingesting NAD+ directly makes little sense, as its oral bioavailability is poorly studied.
| Feature | Nicotinamide Riboside (NR) | Nicotinamide Mononucleotide (NMN) |
|---|---|---|
| Type | A form of Vitamin B3. | The direct precursor to NAD+ in the synthesis pathway. |
| Mechanism | Absorbed by cells and converted into NAD+ through multiple steps. | May potentially enter cells directly via a specific transporter, or is converted to NR first. The exact pathway is still debated. |
| Human Evidence | Slightly better studied; more published randomized human trials. | Catching up rapidly; an increasing number of human trials are becoming available. |
| Typical Study Dose | 250 mg – 1,000 mg per day. | 250 mg – 1,000 mg per day. |
| Clinical Signals | Hints of effects on blood pressure and arterial stiffness (in a small pilot study). | Hints of effects on insulin sensitivity and muscle function (in specific populations). |
Currently, neither substance has a definitively proven, superior clinical benefit for the general population. Both can elevate NAD+ markers in the blood, but whether this translates into long-term, relevant health advantages remains an open question.
What Human Studies Actually Say About NAD+ Supplements (And What They Don't)
The crucial question is not whether a supplement alters blood markers, but whether this leads to tangible health benefits. The existing evidence can be described, at best, as interesting but preliminary.
Cardiovascular Health: A Small Glimmer of Hope?
A small pilot study using NR showed hints of lowered systolic blood pressure and reduced arterial stiffness in healthy older adults (Martens et al., 2018). These are clinically interesting signals, but the study was too small and too short to form the basis of a medical recommendation.
Metabolism and Insulin Sensitivity: Mixed Signals
A study using NMN in overweight, postmenopausal women with prediabetes found improved muscle insulin sensitivity (Yoshino et al., 2021). Conversely, another study using NR in obese men found no such effect (Dollerup et al., 2018). Potential effects appear to depend heavily on the target demographic and their baseline health status.
Muscle Strength and Performance: Inconsistent Results
A Japanese study found slight improvements in gait speed and grip strength in older men following NMN supplementation (Igarashi et al., 2022). Other investigations could not identify clear effects on muscle function or mitochondrial respiration (Dollerup et al., 2020).
Summary of the Evidence
- YES: NAD+ precursors can increase NAD+ metabolites in the blood.
- MAYBE: There are isolated, inconsistent signals for positive effects on surrogate markers like blood pressure, insulin sensitivity, or walking distance in specific populations.
- NO: There is currently no proof that NAD+ supplements reduce hard clinical endpoints such as heart attacks, strokes, dementia, or overall mortality.
The Limits of Current Research: Why You Should Remain Skeptical
The current body of evidence has clear limitations:
- Lack of Long-Term Data: Almost all studies last only a few weeks or months. The safety and utility of taking these supplements for years remain unknown.
- Small Study Populations: Many studies have too few participants to make universally valid claims. The NR pilot study by Martens et al., for instance, included only 24 people.
- Focus on Surrogate Markers: Researchers measure lab values or functional tests, not hard disease endpoints.
- Unclear Meaning of Blood Levels: An increase of NAD+ in the blood does not necessarily mean that sufficient amounts are reaching critical organs like the brain, muscles, or liver. There is no established target value.
Mechanistic plausibility is not clinical efficacy. Just because NAD+ is biologically important does not automatically make supplementation beneficial.
Diagnostics Before Supplementation: What You Should Actually Measure
Before you invest money in an NAD+ supplement, invest in knowledge about your own body. Comprehensive diagnostics will show you where your individual vulnerabilities lie and help you identify more pressing health priorities.
These biomarkers will not prove that you "need" NAD+. Instead, they provide an indispensable baseline to objectively assess your metabolic and cardiovascular state.
| Area | Biomarker | Why is it relevant? |
|---|---|---|
| Metabolism | HOMA-Index | Measures early insulin resistance long before fasting blood sugar rises. Since NMN studies hint at effects on insulin sensitivity, this is a central baseline metric. |
| HbA1c & Fasting Glucose | Provide insight into your long-term blood sugar control. | |
| Cardiovascular | ApoB & Lp(a) | ApoB is a more precise risk marker for cardiovascular risk than LDL cholesterol. Lp(a) is an often-overlooked genetic risk factor. |
| Arterial Stiffness | An early indicator of vascular aging. NR showed preliminary signals here in a pilot study. | |
| Inflammation | hs-CRP | Measures chronic, low-grade inflammation, which accelerates aging processes and potentially increases NAD+ consumption. |
| Organ Function | Liver & Kidney Panel | Ensures your body can safely metabolize and excrete supplements. |
An elevated HOMA-Index or hs-CRP value does not mean NAD+ is the solution. It indicates that you have a relevant health priority that should primarily be addressed with evidence-based measures like nutrition, exercise, or sleep management.
The YEARS Approach: A Clinical Baseline as the Foundation for Decisions
At YEARS, we follow a strict principle: diagnostics precede intervention. Before we discuss targeted supplements, we establish a complete medical baseline.
The YEARS Core® Program is designed exactly for this purpose. In a single day at our Berlin clinic, we analyze over 87 biomarkers and combine them with comprehensive functional diagnostics: a 12-lead ECG, body plethysmography, and arterial stiffness measurement.
The result is not a confusing lab printout, but a 60+ page health report contextualized by a physician. In the subsequent strategy session with the YEARS medical team, you will discuss all identified risks and develop a personalized plan. Only on this data-driven foundation can the question of experimental supplements like NAD+ be meaningfully addressed.
Conclusion: NAD+ is a Legitimate Research Field, Not a Cure-All
The scientific investigation of NAD+ is one of the most exciting fields in aging research. The idea of slowing the age-related decline of this molecule is biologically plausible.
However, taking NMN or NR must currently be viewed as an experimental measure. An NAD+ supplement does not replace exercise, a healthy diet, good sleep, or rigorous medical diagnostics.
Before you invest in an expensive supplement, invest in understanding your body. Only those who know their individual risks can make informed decisions.
Would you like to objectively and comprehensively assess your current health status? Then schedule a complimentary consultation and learn more about the data-driven approach at YEARS.
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This article is for general informational purposes only and does not replace individual medical advice. The decision to take dietary supplements should always be made in consultation with a physician.
Sources
Covarrubias, A. J., Perrone, R., Grozio, A., & Verdin, E. (2021). NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology, 22(2), 119–141. doi: 10.1038/s41580-020-00313-x
Dollerup, O. L., Christensen, B., Svart, M., Schmidt, M. S., Sulek, K., Ringgaard, S., Stødkilde-Jørgensen, H., Møller, N., Brenner, C., Treebak, J. T., & Jessen, N. (2018). A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects. The American Journal of Clinical Nutrition, 108(2), 343–353. doi: 10.1093/ajcn/nqy132
Dollerup, O. L., Chubanava, S., Agerholm, M., Søndergård, S. D., Altıntaş, A., Møller, A. B., Høyer, K. F., Ringgaard, S., Stødkilde-Jørgensen, H., Lavery, G. G., Barrès, R., Larsen, S., Prats, C., Jessen, N., & Treebak, J. T. (2020). Nicotinamide riboside does not alter mitochondrial respiration, content or morphology in skeletal muscle from obese and insulin-resistant men. The Journal of Physiology, 598(4), 731–754. doi: 10.1113/JP278752
Grozio, A., Mills, K. F., Yoshino, J., Bruzzone, S., Sociali, G., Tokizane, K., Lei, H. C., Cunningham, R., Sasaki, Y., Migaud, M. E., Caudill, M. A., Yoshino, M., Imai, S. I., & Ratajczak, J. (2019). Slc12a8 is a nicotinamide mononucleotide transporter. Nature Metabolism, 1(1), 47–57. doi: 10.1038/s42255-018-0009-4
Igarashi, M., Nakagawa-Nagahama, Y., Miura, M., Kashiwabara, K., Yaku, K., Sawada, M., Sekine, R., Fukamizu, Y., Sato, T., Kaisho, T., Nakagawa, T., & Imai, S. I. (2022). Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men. NPJ Aging, 8(1), 5. doi: 10.1038/s41514-022-00084-z
Martens, C. R., Denman, B. A., Mazzo, M. R., Armstrong, M. L., Reisdorph, N., McQueen, M. B., Chonchol, M., & Seals, D. R. (2018). Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nature Communications, 9(1), 1286. doi: 10.1038/s41467-018-03421-7
Vinten, K. T., Trętowicz, M. M., Coskun, E., van Weeghel, M., Cantó, C., Zapata-Pérez, R., Janssens, G. E., & Houtkooper, R. H. (2025). NAD+ precursor supplementation in human ageing: clinical evidence and challenges. Nature Metabolism, 7(10), 1974–1990. doi: 10.1038/s42255-025-01387-7
Yoshino, M., Yoshino, J., Kayser, B. D., Patti, G. J., Franczyk, M. P., Mills, K. F., Sindelar, M., Pietka, T., Patterson, B. W., Imai, S. I., & Klein, S. (2021). Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science, 372(6547), 1224–1229. doi: 10.1126/science.abe9985
Related reading: NAD+ Supplements: Evidence, NMN vs NR & What to Measure | Garmin VO2max Accuracy: Smartwatch Estimate vs. Lab Test | NAD+ & Detox: What Does the Science Really Say? | Longevity clinics compared
Frequently asked questions on this topic
Are NMN and NR even approved in Germany?
The legal status differs between the two substances. Nicotinamide riboside is authorised in the EU as a novel food and may be used in food supplements. Nicotinamide mononucleotide currently has no such EU novel food authorisation, so products are often ordered from abroad and sit in a legal grey area. The classification of NMN has also changed in the United States. Two things follow from this: availability says nothing about efficacy, and orders placed outside regulated channels frequently lack reliable information on purity, dosage and contaminants. Check the current status before buying, because the regulatory picture continues to develop and differs between jurisdictions.
Can I have my NAD+ level measured?
Technically yes, clinically it currently adds little. Some laboratories measure NAD+ or related metabolites in whole blood. The difficulty lies in interpretation. There are no established reference or target values for healthy people, results vary considerably with sample handling, and blood NAD+ says little about levels in muscle, liver or brain. Those are the tissues where an effect would have to occur. A measurement therefore gives you a number without a course of action. The money is better spent on markers with clear thresholds and proven interventions: ApoB, lipoprotein(a), HOMA-IR, hs-CRP, HbA1c, blood pressure and cardiorespiratory fitness. Those values tell you what you can actually work on, and they can be repeated meaningfully over time.
Are there side effects, and who should avoid these supplements?
In human trials to date, NR and NMN have been tolerated well over weeks to a few months, with nausea, digestive complaints and headaches reported most frequently. Meaningful long-term data are entirely absent. Caution is warranted in pregnancy and while breastfeeding, because no data exist. With active or previous cancer, use belongs in medical hands in every case: NAD+ fuels DNA repair enzymes, and what that means in the context of a tumour is discussed theoretically but not resolved. Anyone taking regular medication should also discuss it. High-dose niacin can additionally cause flushing and, at very high doses, elevated liver enzymes. Product quality is a further issue, with analyses repeatedly finding gaps between declared and actual content.
Can I support my NAD+ metabolism without supplements?
The factors with the best evidence cost nothing. Regular physical activity, endurance training in particular, increases mitochondrial capacity and favourably influences NAD+ metabolism in muscle. Sufficient and regular sleep, moderate alcohol use, sun protection and avoiding chronic inflammatory triggers reduce NAD+ consumption through DNA repair processes. A balanced diet covers vitamin B3 requirements easily through meat, fish, legumes and wholegrains. None of this is spectacular, but it acts on documented endpoints across cardiovascular health, metabolism and cognition. No supplement can point to a comparable evidence base for those endpoints. Anyone who still wants to experiment should do so only once sleep, exercise and nutrition are stable, since otherwise no effect can be attributed.
Isn't niacin the same thing and far cheaper?
Niacin and nicotinamide are also NAD+ precursors, available as vitamin B3 for decades at a fraction of the cost of NMN or NR. The metabolic routes differ, however. Nicotinic acid is processed via a different pathway and triggers the characteristic flushing response, with skin redness and a feeling of warmth, at higher doses. Nicotinamide at very high doses inhibits sirtuins, precisely the enzymes that a rise in NAD+ is supposed to benefit. No trial with hard endpoints has shown any of these substances to be clinically superior to the others. Vitamin B3 deficiency is rare on a normal diet in Germany, which makes targeted supplementation unnecessary for most people.
