David Sinclair takes one gram of NMN every morning, mixed into his yogurt. He has discussed it in virtually every major interview over the past five years, dedicated significant sections of his bestselling book Lifespan to the science of NAD+ precursors, and his Harvard laboratory has published foundational research on NMN’s effects in animal models.

Peter Attia, one of the most evidence-rigorous physicians in the longevity space, has reviewed the same evidence and reached the opposite conclusion. He does not take NMN. He is not convinced the human data justifies it, and he is waiting for better trials before changing that position.

Same molecule. Same evidence base. Two leading longevity thinkers with opposite conclusions. That gap is exactly where the MED Report filter is most useful.

NMN, nicotinamide mononucleotide, is the most prominent supplement to emerge from the longevity science movement. It generated $285 million in sales in 2024 and is projected to reach $1.2 billion by 2033. Most people taking it are doing so because influential people say it works.

Should you take it? The human evidence answers that question more clearly than the marketing does.

Let’s run it through the filter.

This is not a supplement built on nothing. The biology behind NMN is genuine and the animal research is compelling. Understanding why requires a brief explanation of NAD+.

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every cell in the body. It is essential for energy production, DNA repair, sirtuin activation (proteins associated with longevity pathways), and cellular stress responses. NAD+ levels decline measurably with age, estimates suggest roughly a 50% decline between the ages of 40 and 60.

NMN is a precursor to NAD+. The body converts NMN into NAD+ after oral intake. Sinclair’s Harvard laboratory and others showed in mice that supplementing NMN could reverse aspects of vascular aging, improve mitochondrial function, and restore muscle endurance in older animals. These findings produced dramatic results, older mice behaving like younger mice, that generated enormous scientific and public interest.

The question the human trials are still trying to answer: does raising blood NAD+ levels in humans translate into the meaningful health outcomes the mouse studies suggested?

So far, the answer is not convincingly yes. That is why Attia is waiting. That is why the MED Report filter reaches the same conclusion.

On the one thing it is supposed to do, raise NAD+ levels, yes. On the outcomes that matter for healthspan, the human evidence is weak, inconsistent, and not yet sufficient to justify the cost.

BLOOD NAD+ LEVELS: Confirmed. NMN consistently and reliably raises blood NAD+ levels across multiple human RCTs. This is the one finding that is robust in humans. The problem is that raising a biomarker is not the same as improving a health outcome. Blood NAD+ is a surrogate marker. The clinical question is what that elevation does to meaningful outcomes, and that is where the evidence falls short.

METABOLIC OUTCOMES - GLUCOSE AND LIPID METABOLISM: No significant benefit. A 2024 systematic review and meta-analysis (Hui et al., Current Diabetes Reports) reviewed 8 RCTs involving 342 middle-aged and older adults. NMN supplementation at doses ranging from 250 to 2,000mg/day for 14 days to 12 weeks showed no significant benefit on fasting glucose, fasting insulin, HbA1c, insulin resistance, or lipid profile. The conclusion was direct: short-term NMN supplementation did not show significantly positive impacts on glucose control and lipid profile.

MUSCLE MASS AND PHYSICAL PERFORMANCE: No significant effects. A 2025 systematic review and meta-analysis (Prokopidis K et al., Journal of Cachexia, Sarcopenia and Muscle) analyzed RCTs comparing NMN and NR versus placebo in older adults. NMN showed no significant effects on skeletal muscle index, handgrip strength, gait speed, 5-chair stand test, knee extension strength, or thigh muscle mass. The conclusion: evidence on NAD+ precursor supplementation and physical performance remains inconclusive, with insufficient evidence to determine whether it can enhance physical performance or reduce frailty.

COGNITIVE FUNCTION: No significant improvement in healthy older adults. A double-blind randomized controlled trial in 20 healthy older men (mean age 65+) found that NMN supplementation at 250mg/day for 12 weeks significantly raised blood NAD+ levels but did not significantly affect cognitive function assessed by validated instruments. No human trials have tested whether NMN prevents dementia or age-related cognitive decline.

BLOOD PRESSURE: A modest signal, but context matters. A 2026 meta-analysis (Liao et al., Nutrients) found NMN supplementation was associated with a reduction of 2.15 mmHg in diastolic blood pressure in adults with elevated blood pressure. This is a real finding. However, for context: magnesium glycinate [Edition #005] reduces systolic blood pressure by 2.81 mmHg in 38 RCTs at $15/month. NMN’s blood pressure finding costs 3-7x more for a smaller effect on a single pressure measurement.

This is where the answer to “Should you take it?” becomes clearest. The following comparison uses evidence from The MED Report editions already published:

If you are not already taking magnesium glycinate [Edition #005], creatine monohydrate [Edition #003], and quality omega-3 EPA+DHA [Edition #007], and not doing resistance training twice a week [Edition #006], spend your money there first. The combined evidence for those four interventions is orders of magnitude stronger than NMN at current human data, at a combined cost of approximately $55–65/month. That is less than NMN alone.

The MED Report filter does not ask whether NMN might eventually prove useful. It asks whether the current human evidence justifies the current price for your demographic. The answer is no.

The Noise verdict on NMN requires intellectual honesty about its limitations. This is not a case where the evidence is overwhelmingly negative. It is a case where the evidence is insufficient.

The trials are mostly short, 8 to 12 weeks. NAD+ biology may require longer supplementation periods to show effects on meaningful outcomes. The trials are mostly small, most include fewer than 100 participants. Larger, longer, well-powered trials are underway and may change this verdict.

A 2026 systematic review using GRADE/CINeMA methodology rated the evidence across 14 metabolically comparable outcomes as Very Low certainty, not because effects were clearly absent, but because the evidence base is structurally too heterogeneous and underpowered to draw reliable conclusions. (Note: this analysis was a preprint at time of publication and has not yet completed peer review.)

Attia’s position is nuanced and worth noting: he does not take NMN because the human evidence has not yet met the bar he requires before recommending an intervention. He is not saying it will never work, he is saying the data is not there yet. That is the same standard the MED Report applies.

Sinclair’s position is also honest when pressed: he takes it as a personal bet on the biology, acknowledging the human trial evidence is early. He is making a forward-looking wager as a researcher who believes in the mechanism. That is his prerogative. It is not the same as evidence.

Should you take NMN? The answer depends on one question: are you already doing the things with strong evidence?

If you are not taking magnesium glycinate [Edition #005], creatine monohydrate [Edition #003], and quality omega-3 EPA+DHA [Edition #007], and not doing resistance training twice a week [Edition #006], the answer is no. Spend your money there first. The combined evidence for those four interventions is orders of magnitude stronger than NMN at current prices.

If you are already doing all of those things and have discretionary budget for speculative supplementation with a clean safety profile, NMN is one of the safer bets in the speculative category. But go in knowing you are in speculative territory, not evidence-based territory.

NMN is well-tolerated and safe at doses up to at least 1,200mg/day in short-term trials. No significant adverse effects have been reported. The safety profile is clean. The issue is not safet, it is efficacy.

One regulatory note: The FDA clarified in 2025 that NMN is not excluded from the definition of a dietary supplement in the United States. NMN supplements are legal to sell and purchase in the US.

The longevity supplement industry has a reliable pattern: compelling animal data, influential advocates, aggressive marketing, and a price tag that arrives years before the human outcome trials catch up.

NMN is the most prominent example of this pattern. The mouse data is real. The biology is plausible. The researchers advocating for it are legitimate scientists making reasonable forward-looking bets. None of that changes what the human evidence currently shows.

40 to 70, health-conscious, evidence-adjacent, is the primary target of NMN marketing. The supplement industry knows you follow David Sinclair. It knows you listen to longevity podcasts. It knows you will pay $80/month for something a Harvard professor takes.

The MED Report filter does not care about Harvard professors. It cares about human RCT data. And the human RCT data on NMN currently shows one thing clearly: it raises blood NAD+ levels. Everything else is a work in progress.

Should you take it? Not yet. Come back in five years. This verdict may change.

Before considering NMN, confirm you are doing the following:

If you are doing all four and want to experiment with NMN, the safety profile is clean. Go in knowing you are speculating, not following the evidence. The biology is real. The human outcome evidence is not yet there.

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