Most people asking "what is NAD+" get told the same thing: it's the coenzyme that powers your mitochondria, it falls with age, and supplements put it back. The first part is true. The last part has been argued for a decade on surprisingly thin head-to-head data — because almost no trial had ever put the main NAD+ precursors against each other in the same group of people.

In January 2026, one finally did. And the result creates an odd situation for Australia: the trial measured exactly the thing that Australian supplement labels are forbidden from claiming.

The first three-way head-to-head in humans

A randomised, open-label, placebo-controlled study of 65 healthy adults, published in Nature Metabolism on 15 January 2026, compared three NAD+ boosters taken once daily for 14 days: nicotinamide mononucleotide (NMN) at 1,000 mg/day, nicotinamide riboside (NR) at 1,000 mg/day, and plain nicotinamide (Nam) at 500 mg/day, against placebo.

The headline findings:

  • NMN and NR performed comparably, roughly doubling whole-blood NAD+ over the fortnight. Neither clearly beat the other.
  • Nicotinamide did not. It produced a sharp, transient rise in the blood NAD+ metabolome within hours of a dose, then left baseline NAD+ essentially unchanged after 14 days.
  • The routes differ. The authors attribute NR and NMN's sustained effect to the Preiss–Handler pathway, while rapidly absorbed nicotinamide works acutely through the salvage pathway.

That last point is the genuinely new bit, and it isn't about the pills at all.

The gut bacteria twist

Using ex vivo fermentation with human faecal microbiota, the researchers showed that NR and NMN are converted by gut microbes into nicotinic acid (NA) — a potent NAD+ precursor in its own right — and that this specifically enhanced microbial growth and short-chain fatty acid production. The interpretation offered is a dual effect: a systemic NAD+ rise plus a microbiome-level one.

Read that carefully. The microbial part of the story was demonstrated in a benchtop fermentation system, not inside living participants. It is a mechanistic inference, and a plausible one, but it has not been shown to produce any health outcome in a person.

Two further caveats worth stating plainly. The trial was open-label — participants knew what they were swallowing — which matters less for a blood metabolite than for a symptom score, but it isn't a blinded design. And the work was led by scientists at Nestlé Research, Nestlé Health Science and Cryptobiotix, organisations with commercial interests in this category, using branded commercial products. Industry funding doesn't make a result wrong; it does mean replication by an independent group is the test that counts.

What raising a blood marker does and doesn't prove

Doubling circulating NAD+ is a pharmacodynamic result: it shows the compound is doing something measurable. It is not a clinical outcome.

This is where the wider literature stays stubbornly flat. A 2026 systematic review and meta-analysis pooling 12 randomised controlled trials and 513 participants found that NMN significantly raised blood NAD+ levels — and that most clinically relevant outcomes did not differ from control. The same review flagged risk-of-bias concerns in seven of the trials and high risk of bias in the remaining five, concluding that exaggeration of NMN's benefits may exist in the field.

The NR literature reads similarly. A review in Science Advances examining what is actually known about oral NR in humans concluded that, collectively, it has displayed few clinically relevant effects, despite reliably lifting NAD+.

So the honest summary in September 2026: NMN and NR raise the marker, comparably, within about two weeks. Whether that translates into anything a person would notice — strength, walking distance, cognition, metabolic health — remains largely unproven, with individual positive signals (such as NR in peripheral artery disease) awaiting replication in larger trials.

For context on the injectable side, NAD+ given intravenously still has very little published human evidence, and it's worth remembering NAD+ is a coenzyme, not a peptide — it sits in the same conversation as the compounds in our peptides library largely for cultural reasons, not biochemical ones.

Is NMN legal in Australia? The claim you can't make

Australia's position changed on 10 December 2025, when the TGA added NMN to the Permitted Ingredients Determination. Oral NMN can now appear in listed medicines, subject to hard limits: maximum 500 mg per day, oral route only, a recommended duration of use of 12 weeks or less, adults only, not for pregnant or lactating women. Those conditions run to 10 December 2027 under a period of sponsor exclusivity. Nicotinamide riboside chloride, nicotinamide and nicotinic acid were already available as permitted ingredients; NAD, NAD+ and NADH themselves remain non-permitted in listed medicines.

Two things follow directly from the new trial.

First, the dose gap. The Nature Metabolism study used 1,000 mg/day of NMN — double what an Australian listed medicine may deliver. Nothing in the trial tells us whether 500 mg/day produces the same doubling, and dose-response for blood NAD+ is not well mapped at the low end.

Second, and more striking: the finding is unclaimable here. TGA guidance on NAD, NAD+, NADH and NMN representations states that there are currently no permitted indications referencing NAD, NAD+, NADH or NMN. Phrases like "boost NAD+ levels" or "maintain NAD+ levels" are not permitted indications for a listed medicine. So an Australian product can legally contain NMN and legally cannot tell you what the best evidence for NMN actually shows it does. If you see that claim on an Australian shelf or website, the product is out of step with the rules — a useful compliance signal for shoppers.

More background on the compound, its pathways and the trial record sits on our NAD+ profile page. If you want new trial data and TGA decisions summarised as they land, join the free updates list.

FAQ

Is NMN legal in Australia?

Yes, with conditions. The TGA made NMN a permitted ingredient for oral listed medicines on 10 December 2025, capped at 500 mg per day for up to 12 weeks in adults. NAD, NAD+ and NADH remain non-permitted ingredients in listed medicines.

NMN vs NR: which one raises NAD+ more?

In the first head-to-head human trial (65 adults, 14 days, published January 2026), NMN and NR at 1,000 mg/day performed comparably, both roughly doubling whole-blood NAD+. Plain nicotinamide did not sustain any increase.

Does raising NAD+ actually improve health?

That remains unproven. A 2026 meta-analysis of 12 randomised trials found NMN reliably raised blood NAD+ but did not significantly shift most clinically relevant outcomes, with risk-of-bias concerns across every included trial.

Can Australian supplements say they boost NAD+?

No. TGA guidance states there are currently no permitted indications referencing NAD, NAD+, NADH or NMN levels, so claims such as "boosts NAD+" cannot lawfully be made for a listed medicine in Australia.

Sources

This article is independent information, not medical advice. NAD+ is a coenzyme, not a peptide; oral NMN is a TGA-permitted listed medicine ingredient in Australia under strict conditions, while NAD+ and NADH are not permitted ingredients and NAD+ infusions are not TGA-approved therapies. Speak with a qualified Australian health professional before acting on anything here.