What NAD+ does — and why its decline matters
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme present in every living cell. It is central to energy metabolism, DNA repair, sirtuin activation, and immune function. The problem: NAD+ levels decline by roughly 50% between ages 40 and 60, a trajectory that is mechanistically linked to many features of ageing. Both NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are oral precursors that the body converts into NAD+. NMN sits one step closer to NAD+ in the biosynthesis pathway — the typical route is NR → NMN → NAD+ — which in theory should give it an efficiency advantage. In practice, the clinical picture is more nuanced.
The clinical evidence for NMN
A 2024 meta-analysis in Critical Reviews in Food Science and Nutrition pooled 12 randomised controlled trials involving 513 participants. The consistent finding: NMN reliably elevates NAD+ in the bloodstream. What is less consistent is what happens downstream. The meta-analysis found no significant effect on fasting glucose, insulin, HbA1c, or blood lipids — the metabolic markers most people care about.
That said, several trials showed meaningful functional outcomes. A 2022 Japanese dose-finding trial in 80 healthy adults found optimal efficacy at 600mg daily over 60 days. A 2024 study in older adults aged 65–75 found 250mg daily for 12 weeks produced significantly faster walking speeds and improved sleep quality — tangible benefits for this age group. A 2021 trial in prediabetic women found NMN increased muscle insulin sensitivity. A 2023 arterial stiffness trial produced no overall group difference, but the subgroup with above-average blood glucose showed significant improvement equivalent to approximately 2 years of vascular age reversal.
The 2024 meta-analysis of 12 RCTs confirmed NMN reliably elevates NAD+ — but evidence for downstream clinical benefits remains limited and inconsistent across the general population.
The clinical evidence for NR
NR has a longer clinical trial history. The NR-SAFE trial, published in Nature Communications in 2023, enrolled 20 Parkinson's patients on 1,500mg twice daily for 4 weeks. The compound was safe, increased cerebral NAD+ levels (measured by phosphorus MRS), and was associated with measurable improvement in motor symptoms — a notable signal in a neurodegenerative disease. A 2023 dose-escalation study in mild cognitive impairment also showed increased blood NAD+ with good tolerability up to 1,000mg daily.
The less encouraging data: a 2019 trial in obese men gave 2,000mg of NR twice daily for 12 weeks — an aggressive dose — and found no improvement in insulin sensitivity despite clear NAD+ elevation. This recurring disconnect between NAD+ elevation and downstream outcomes is the central unresolved question in the field. That said, NR has achieved GRAS (Generally Recognised as Safe) status, giving it a regulatory head start over NMN in most jurisdictions.
Head to head: what the January 2026 trial settled (and didn't)
The most direct comparison to date was published in Nature Metabolism in January 2026, a collaboration between Haukeland University Hospital and Nestlé Research. Sixty-five healthy adults were randomised to 1,000mg NMN, 1,000mg NR, or placebo for 14 days.
The key finding: at equivalent doses, NMN and NR showed approximately equal efficacy. Both roughly doubled circulating NAD+ after 14 days, with no statistically significant difference between them. Plain nicotinamide (ordinary vitamin B3) showed no NAD+ elevation at all. What the trial does not answer — because 14 days is far too short — is which compound, if either, produces better long-term clinical outcomes.
At equivalent doses, NMN and NR roughly doubled circulating NAD+ in 14 days with no significant difference between them. The question of which is clinically superior over months or years remains open. (Cuenoud et al., Nature Metabolism, 2026)
Safety: what we know and what we don't
In clinical trials, NMN appears safe at 900–1,250mg daily for 4–10 weeks, with no severe adverse events reported. NR has been tested at even higher doses — 3,000mg per day in the NR-SAFE trial — also without serious safety signals. Both have mild, infrequent gastrointestinal effects in some participants.
The important caveat: neither compound has long-term human safety data beyond 6 months. A theoretical concern is cancer risk — NAD+ fuels cellular metabolism in both healthy and cancerous cells, and NAMPT (the enzyme that generates NAD+) is overexpressed in many cancers. This is a legitimate question, not a proven risk, but it is worth noting. Some researchers have also cautioned that exaggeration of NMN supplementation benefits exists in the field, a reminder to weigh commercial claims carefully.
The Australian regulatory picture
On 10 December 2025, the TGA (Therapeutic Goods Administration) added NMN to the Therapeutic Goods (Permissible Ingredients) Determination. Australia became the first country globally to formally permit NMN in listed therapeutic medicines. The TGA set a maximum recommended daily intake of 500mg, with use restricted to adults (excluding those who are pregnant or breastfeeding). SyncoZymes was granted a 2-year market exclusivity period (December 2025 to December 2027), and products are now available through Chemist Warehouse.
NR, by contrast, has been available in Australia as a listed complementary medicine (AUST L) for years, with no equivalent dosing cap. On cost, NR retails for roughly $40–70 per month, whilst NMN runs $50–120. NR is approximately 30–50% cheaper, which matters if you are planning to take either compound long-term.
The bottom line
Both NMN and NR reliably boost NAD+ by similar amounts at equivalent doses. Neither has yet proven longevity benefits in humans — the gap between NAD+ elevation and meaningful clinical outcomes is the field's central unanswered question. Where positive results exist (functional performance, vascular function in specific subgroups, motor symptoms in neurodegeneration), they are promising but not yet sufficient to drive broad recommendations.
NR is cheaper, has a longer trial history, and carries established regulatory status. NMN now has TGA approval in Australia, which reflects demonstrated safety at 500mg daily rather than proven efficacy. For most people, lifestyle fundamentals — sleep, exercise, stress management, nutrition — should come first. If you choose to supplement with either compound, the evidence says both work; choose based on cost, availability, and tolerance. And hold the decision lightly until longer-term human data arrives.
References
- Critical Reviews in Food Science and Nutrition (2024). NMN supplementation meta-analysis: 12 RCTs, 513 participants.
- Igarashi, M., et al. (2022). Dose-dependent effects of NMN in healthy adults over 60 days. GeroScience.
- Kim, M., et al. (2024). NMN improves walking speed and sleep quality in adults aged 65–75 (12 weeks, 250mg daily).
- Yoshino, M., et al. (2021). NMN increases muscle insulin sensitivity in prediabetic women. Science.
- Katayoshi, T., et al. (2023). NMN and arterial stiffness: 12-week RCT in 36 adults. Scientific Reports.
- Brakedal, B., et al. (2023). NR-SAFE: safety and efficacy of high-dose NR in Parkinson's disease (n=20). Nature Communications.
- Dollerup, O. L., et al. (2019). NR supplementation does not improve insulin sensitivity in obese men. American Journal of Clinical Nutrition.
- Cuenoud, B., et al. (2026). NMN and NR double circulating NAD+ equivalently at 1,000mg: 3-arm RCT (n=65). Nature Metabolism.
- Therapeutic Goods Administration (2025). Therapeutic Goods (Permissible Ingredients) Determination: NMN inclusion, December 2025.
- Journal of Cachexia, Sarcopenia and Muscle (2025). NMN/NR supplementation does not improve muscle mass or function in adults over 60: meta-analysis.