Is NMN/NR backed by human studies, or mostly mouse research?

The honest answer is: both, but they're at different stages. The foundational work — showing that NAD+ precursors extend lifespan and reverse markers of metabolic decline — really is mostly rodent data. Human research has grown substantially over roughly the last decade, but it remains smaller in scale and shorter in duration than the animal literature.

On the human side, there's now a meaningful body of randomized, placebo-controlled trials. A systematic review of NMN trials identified ten randomized controlled studies covering 437 participants, with doses ranging from 150 to 1,200 mg per day and average follow-up under ten weeks, evaluating physical performance and safety.3 Separately, controlled trials have tested NMN in healthy middle-aged and older adults over 8–12 weeks and found it well tolerated with no significant adverse effects.4 NR has an even longer trial history, tested in humans at 100–2,000 mg/day for up to 12 weeks across more than a dozen published studies, most reporting good safety and elevated blood NAD+ metabolites.5

Where the evidence is thinner: long-term studies (years, not weeks), large sample sizes (most trials run 15–40 people), and hard clinical endpoints like disease prevention or lifespan in humans — those simply don't exist yet. So when you see a headline claiming NMN "reverses aging," it's almost always extrapolating from mouse data or short-term human biomarker changes, not from a trial that measured actual aging outcomes in people.

Bottom line: NMN and NR are no longer purely mouse-study supplements — there's real, published human safety and biomarker data — but claims about disease prevention or dramatic anti-aging effects in humans are still ahead of the evidence.

"Improved Physical Performance Parameters in Patients Taking NMN: A Systematic Review of RCTs" — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11365583/

"Chronic nicotinamide mononucleotide supplementation elevates blood NAD+ levels and alters muscle function in healthy older men," npj Aging — https://www.nature.com/articles/s41514-022-00084-z

Same study, earlier PMC-hosted version (trial history background) — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9158788/