NMN
/ Nicotinamide mononucleotide; NAD+ precursor (small molecule)ALIAS · NMN · β-nicotinamide mononucleotide
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Tier 2. Small RCTs in older adults (Yoshino 2021 NMN in postmenopausal prediabetic women; subsequent NMN exercise and ageing studies). NMN is the proximal NAD+ precursor most associated with the David Sinclair laboratory and has substantial preclinical lifespan and metabolic literature. In the US, NMN was previously marketed widely as a dietary supplement; FDA's 2022 letter to industry took the position that NMN is excluded from the dietary supplement definition because it had been investigated as an investigational new drug, creating ongoing regulatory ambiguity.
NMN is the immediate precursor to NAD+ in the salvage pathway; it is converted to NAD+ by NMNAT (nicotinamide mononucleotide adenylyltransferase) enzymes. The proposed mechanism for NMN supplementation is direct elevation of cellular NAD+ pools, with downstream consequences on sirtuin-mediated deacetylation, mitochondrial biogenesis, and DNA-damage-response capacity. Cellular uptake is partially mediated by the SLC12A8 transporter (Grozio 2019 — claim subsequently debated), with conversion to nicotinamide riboside extracellularly in some compartments before reabsorption.
Tier 2. Yoshino 2021 reported a randomised placebo-controlled trial of NMN 250 mg daily for 10 weeks in postmenopausal women with prediabetes, with skeletal-muscle insulin sensitivity as the primary endpoint. Liao 2021 and other small studies have explored NMN supplementation in exercise-trained populations. Outcome sizes are modest and the trial population is select; no Phase 3 trial evidence supporting any specific clinical claim is available.
In published small RCTs and Phase 1 work, oral NMN is well tolerated at doses up to 1200 mg daily over weeks-to-months. Long-term safety data are limited and the regulatory ambiguity in the US around NMN-as-supplement has constrained the development of post-marketing safety registries.
Regulatory status
- FDA status:
- Not FDA-approved
The geroscience case for NMN is real but the human outcome database is small. Translation from rodent lifespan and metabolic effects to human disease-modifying outcomes remains hypothesis-generating. NMN is sold widely in the US in the supplement channel under product specifications that vary substantially by manufacturer; the 2022 FDA position has not led to broad enforcement.