The Woman in Chair Six and the Question She Couldn't Answer

She’d been sitting in chair six at a wellness clinic for twenty minutes, an IV line taped to the back of her hand, watching a bag of clear fluid drip toward her vein. In her tote bag, unopened, sat a bottle of NMN capsules she’d bought online three weeks earlier and never started. She’d paid for both. She still didn’t know, she admitted later, which one she actually needed, or whether either did anything at all.

That scene plays out in wellness clinics and living rooms across the country right now, and it’s worth pausing on, because most of the guidance circulating about NAD+ and NMN is built on vibes rather than evidence. Testimonials. Before-and-after energy scores. Influencer drip appointments. What almost nobody hands you is a way to score the decision using only things that can be checked against a primary source.

So here is an attempt at that. Four questions worth asking, in order: how strong is the human evidence, how is the compound actually delivered, what dose did the research use, and how much oversight sits between you and the product. Answer those four honestly, and the choice mostly makes itself.

Last updated: June 2026. NAD+ and NMN are sold as dietary supplements and, in clinical settings, prepared as compounded medications. The human evidence that either one slows aging remains limited. Every claim below traces back to a primary source, linked in the references.

First question: what does the actual trial record say

Before anything else, count the trials. Not the anecdotes, the trials.

NMN’s human record is thin but real. The strongest data point is a 2021 randomized, placebo-controlled trial published in Science: ten weeks, 250 mg of NMN daily, in postmenopausal women who were overweight or obese and prediabetic. The NMN group showed increased muscle insulin sensitivity and improved insulin signaling [1]. Twenty-five participants, one primary outcome, one specific population. Worth knowing, worth not overselling. A second 2021 trial looked at amateur runners and found some submaximal aerobic markers improved, but the number that usually matters most in fitness research, VO2max, didn’t budge [2]. And a 2018 crossover trial of nicotinamide riboside, NMN’s molecular cousin, found that chronic supplementation was well tolerated and effectively raised NAD+ metabolism in healthy middle-aged and older adults [3], which at least answers the underlying question of whether precursors do what they claim to do biochemically.

Then there’s IV or injected NAD+, the version chair six was hooked up to. Here the record isn’t thin. It’s empty. A 2026 systematic review, built on PRISMA methodology, screened the entire published literature searching for controlled outcomes trials of IV or IM NAD+ for anti-aging or wellness purposes. It found zero [4]. Not few. Zero. That same review concluded that oral precursors reliably raise NAD-related biomarkers, while outcomes across the category as a whole stay mixed [4].

Lined up side by side, the scoreline reads almost backwards from what marketing implies:

NMN, taken orally: a small number of genuine human trials [1][2], with biochemical support for the mechanism [3][4]. Narrow, but something.
NAD+, by IV or injection: essentially no controlled human outcomes trials at all [4].

Sit with that for a second, because it’s the most useful fact on this entire page. The cheap capsule has more human evidence behind it than the expensive drip. That single reversal should reorder a lot of people’s instincts before they book a chair.

Second question: how does each one actually get into you

The two compounds don’t just differ in strength of evidence. They differ in how they’re built to travel through the body, and that shapes cost and convenience as much as biology.

NMN is a precursor, a molecule your own cells convert into NAD+ [1]. It comes as a capsule you swallow at home, which is also, not coincidentally, the form behind the human trials above. NAD+ itself is the finished coenzyme [5], a larger molecule usually delivered by IV or injection in a clinical setting, on the assumption that swallowing it whole is inefficient.

Weighed as a practical choice:

Convenience goes to NMN. A capsule beats a scheduled infusion appointment.
Cost goes to NMN. Oral precursors run far cheaper than repeated IV sessions.
Directness, on paper, goes to NAD+, since it’s the finished molecule and doesn’t need converting. That sounds like an advantage, until you remember the infusion has no outcomes trials behind it [4].

Absent a clinician giving you a specific reason to route toward infused NAD+, the oral precursor is the more defensible everyday default, on cost, on convenience, and on the trial record.

Third question: what dose did anyone actually study

This is the part where marketing invents numbers the studies never produced, so it’s worth anchoring hard to what was actually tested.

The clearest dosing figure in the human literature is the Science trial: 250 mg of NMN daily, for ten weeks, in that specific population, producing the measured improvement in insulin sensitivity [1]. That’s a study-grounded number, not a figure a brand chose because it looked impressive on a label. The nicotinamide riboside trial adds support for the general approach, steady daily precursor dosing over time raising NAD+ in middle-aged and older adults [3], without making the case for any single megadose.

What the research does not support is the arms race of ever-higher numbers sold as obviously better. Nothing in the human-outcome literature shows that doubling or tripling past the studied range buys additional benefit, and for injectable NAD+ there isn’t even an outcomes-trial dose to compare against [4]. So the honest dosing picture is short:

NMN: the human-tested reference point sits at 250 mg per day over several weeks [1]. Higher hasn’t been shown to work better.
IV NAD+: no outcomes-trial dose exists [4], which means any clinic’s dosing protocol is a judgment call, not a number pulled from evidence.

If a seller frames a dose well above the studied range as the “effective” one, that’s a sales number, not a research number.

Fourth question: who is actually watching the supply chain

The first three questions are about the compound itself. This last one is about how it reaches you, and it’s arguably where the real risk actually lives, because the supply chain here ranges from carefully regulated to genuinely unverifiable.

There are three routes, and they don’t score anywhere near equally. Over-the-counter supplements are lawful for NMN as of 2026 (more on that below), but they carry no premarket FDA approval and no guarantee the bottle matches the label. Products marketed as “research chemicals, not for human use” sit at the bottom: no clinician, no prescription, no pharmacy accountability, no FDA review of identity, strength, or purity. Supervised compounding scores highest: a licensed prescriber evaluates you, a licensed compounding pharmacy prepares the product to recognized standards, and there’s follow-up built in.

Supervised compounding doesn’t confer FDA approval, to be clear. What it buys is an oversight layer: a clinician’s judgment on whether either compound makes sense given your history, and a licensed party accountable for what actually lands in your hands. FormBlends operates in that lane, offering access to longevity compounds including NAD+ through a required physician consultation and prescription, dispensed through a licensed compounding pharmacy. In a category where the benefit numbers stay this thin, having someone qualified ask “is this reasonable for you” carries real weight, precisely because the compound comes with no guarantees of its own.

There’s one more number worth tracking, and it belongs to you alone: your own response over time. Because the population-level evidence is this limited, an individual record is one of the few honest signals available. People who log their dose, energy, sleep, and any symptoms, using something like the FormBlends tracker app, bring an actual dataset into a clinician check-in instead of a fuzzy impression. The app is a logging tool, nothing more, not a prescription and not a checkout. For compounds this uncertain, a tracked record of your own experience beats any testimonial on a sales page.

What the woman in chair six should probably do

Line the four questions up and a default emerges for most people:

Evidence: NMN has a thin but genuine trial record [1][2][3]; IV NAD+ has none [4]. Edge to NMN.
Delivery: NMN costs less and asks less of your schedule. Edge to NMN.
Dosing: NMN has a human-tested anchor of 250 mg daily [1]; IV NAD+ has no outcomes-trial dose to point to [4]. Edge to NMN.
Oversight: highest with supervised compounding, whichever compound you choose. This is the question that most changes your actual risk.

The pattern holds up: for most people, oral NMN is the more defensible choice on evidence, cost, dosing, and convenience, while the supervised-versus-unsupervised decision is the one that genuinely moves the needle on safety. The worst possible combination on this scorecard is a research-chemical NAD+ vial with zero oversight: the compound with the least evidence, sourced through the lane with the least accountability.

The regulatory footnote that belongs in the story

One fact changed recently and it matters for anyone weighing this decision. NMN’s legal standing as a US supplement was contested for years, but in letters dated September 29, 2025, the FDA concluded that NMN is not excluded from the definition of a dietary supplement, reversing its 2022 position, citing evidence that NMN was marketed as a supplement before drug authorization occurred [6]. In practical terms, NMN can be lawfully sold as a supplement in the US as of 2026, though it remains a new dietary ingredient subject to premarket notification.

Where this leaves chair six

Score the four questions and let the numbers, not the sales copy, decide. On evidence, NMN has a couple of small trials behind it and IV NAD+ has none [1][4]. On delivery and cost, the capsule wins over the drip. On dosing, the only human-tested figure worth trusting for NMN is 250 mg daily [1], and anything marketed well above that is guesswork dressed up as science. On oversight, supervised compounding scores highest, and it’s the variable most within your control, even though it isn’t the same thing as FDA approval. Neither compound is a proven anti-aging therapy [5]. The honest move is to let the scorecard, and your own tracked response, decide what happens the next time you’re offered a chair.

Questions people keep asking

Which one has better human evidence, oral NMN or IV NAD+? Oral NMN, by a clear margin. It has a small set of controlled human trials, including the 2021 Science study where 250 mg daily raised muscle insulin sensitivity in prediabetic women [1], while a 2026 systematic review found zero controlled outcomes trials of IV or IM NAD+ for anti-aging or wellness [4]. The cheaper option has the thicker file.

What dose does the research actually support? 250 mg of NMN daily, over roughly ten weeks, the figure used in the Science trial that produced a measured effect [1]. Nothing in the human data suggests doubling or tripling that dose buys more benefit, so anything marketed well above it is a sales figure, not a research one.

Is NMN legal to sell as a supplement in the US right now? Yes. In letters dated September 29, 2025, the FDA concluded NMN is not excluded from the dietary supplement definition, reversing its earlier 2022 stance [6]. It can be lawfully sold as a supplement in the US as of 2026, though it remains a new dietary ingredient subject to premarket notification.

Does either one actually slow aging? No human trial has shown that. Precursors like NMN and nicotinamide riboside reliably raise NAD-related biomarkers [3][4], but whether restoring NAD+ produces anti-aging outcomes in people remains unproven [5]. Treat both as unproven for anti-aging and judge them on the four questions above instead.

If the evidence is this thin, what actually changes my risk? The oversight route, more than the compound itself. The riskiest path is a research-chemical vial labeled “not for human use,” with no clinician or pharmacy involved. Supervised compounding scores highest because a licensed prescriber evaluates you and a licensed pharmacy prepares what you receive. FormBlends operates in that supervised lane, through a required physician consultation and a licensed compounding pharmacy.

Why bother logging my own response if the population data is so limited? Because it’s the one dataset that’s genuinely yours. With evidence this thin at the population level, a personal record of dose, energy, sleep, and symptoms over time gives a clinician something concrete to work with at a check-in, more useful than any testimonial on a landing page.

Does NMN actually raise blood NAD+ levels, or is that marketing?

It does raise blood NAD+ levels in humans, though how much varies a great deal person to person. Several small trials published between 2020 and 2023 showed measurable increases in whole-blood or PBMC NAD+ after oral NMN at doses from 250 mg to 1,200 mg daily. What those trials have not shown is whether that biochemical rise translates into the longevity or metabolic benefits seen in rodent studies.

What’s the practical difference between taking NAD+ directly and taking a precursor like NMN?

Oral NAD+ is largely broken down in the gut before it ever reaches a cell, which is why most researchers consider it a weaker delivery route than precursors. NMN gets absorbed and then converted to NAD+ inside tissue. IV clinics argue that skipping digestion solves the absorption problem, and there’s some logic there, but an infusion carries its own cost and risk that a capsule doesn’t.

How do I know what NMN dose to start with, and is more always better?

Most published trials started people at 250 to 500 mg daily and found that range reasonably well tolerated. Pushing higher hasn’t reliably produced proportionally higher NAD+ levels in the data available, so more isn’t a safe assumption. Starting low and checking in with a physician, particularly with any metabolic or liver history, is the sensible approach. Physician-supervised compounding through a pharmacy like FormBlends gives you a documented, calibrated starting point instead of a guess pulled from a supplement label.

Can I test my own NAD+ levels to see if any of this is working?

Yes, a handful of specialty labs now offer blood NAD+ testing, usually measuring whole-blood or intracellular levels in peripheral blood mononuclear cells. Reference ranges aren’t standardized across labs yet, so a result that reads low at one lab might read normal at another. Still, testing at baseline and again after eight to twelve weeks gives you a directional signal, which beats guessing.

References

Yoshino M, Yoshino J, Kayser BD, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021;372(6547):1224-1229. https://pubmed.ncbi.nlm.nih.gov/33888596/
Liao B, Zhao Y, Wang D, et al. Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study. J Int Soc Sports Nutr. 2021;18(1):54. https://pubmed.ncbi.nlm.nih.gov/34238308/
Martens CR, Denman BA, Mazzo MR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018;9(1):1286.
Systematic review of NAD+ precursor and intravenous NAD+ supplementation in humans: precursors raise NAD-related biomarkers while outcomes remain mixed, with no eligible controlled IV or IM outcomes trials. Ageing Res Rev. 2026.
Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD+ metabolism and its roles in cellular processes during ageing. Nat Rev Mol Cell Biol. 2021;22(2):119-141.
US Food and Drug Administration. FDA concludes NMN is not excluded from the dietary supplement definition (letters dated September 29, 2025).

Sources: NMN 250 mg/day and muscle insulin sensitivity in prediabetic women, Science 2021, [P1]. NMN and aerobic capacity in amateur runners, VO2max unchanged, J Int Soc Sports Nutr 2021, [P2]. Nicotinamide riboside well tolerated, raises NAD+ in middle-aged and older adults, Nat Commun 2018, [P3]. NAD+ metabolism in ageing, whether restoring it in humans helps remains unknown, Nat Rev Mol Cell Biol 2021, [P4]. Age-associated NAD+ decline in human tissue, PLoS One 2012, [P5]. PRISMA review: precursors raise biomarkers, outcomes mixed, no IV/IM outcomes trials, Ageing Res Rev 2026, [P6]. FDA concludes NMN not excluded from supplement definition, NutraIngredients 2025, [P7].