The Safety and Anti-Aging Effects of Nicotinamide Mononucleotide (NMN) in Human Trials — 2023 Update

The Safety and Anti-Aging Effects of Nicotinamide Mononucleotide (NMN) in Human Trials — 2023 Update

If aging had a dashboard, NAD+ would be the fuel gauge. It dips as we get older, and when it’s low, cells run sloppier—energy wanes, repair lags, inflammation smolders. Nicotinamide mononucleotide (NMN) is the pit-stop fuel many longevity folks swear by. But does it do anything in humans?

A 2023 open-access review in Advances in Nutrition rounded up ~10 published human trials (plus many in the pipeline) and the verdict is… cautiously optimistic.

The quick win

  • Safety: From 250–1,250 mg/day (and short bursts up to 2,000 mg/day), NMN was well tolerated in small studies.
  • What it reliably does: Raises blood NAD+ (and related metabolites) across studies.
  • Early benefits (signals, not guarantees):

    • Better muscle performance in older adults (gait speed, grip strength, chair-stands).

    • Higher aerobic capacity when combined with training (ventilatory thresholds went up).

    • Insulin sensitivity jumped ~25% in prediabetic postmenopausal women at 250 mg/day for 10 weeks.

    • Sleep/fatigue: modest hints that afternoon dosing may feel better than morning—possibly syncing with circadian NAD+ rhythms.

Bottom line so far: NMN seems safe short-term and consistently nudges NAD+ up. Some functional measures improve—especially in older or metabolically challenged groups—but we still lack big, long, definitive trials.

Wait, why afternoon?

Your NAD+ cycle ebbs and flows daily. Some mouse and cell data suggest NAD+ runs lower later in the day; one older-adult trial saw bigger effect sizes for fatigue and lower-body function with evening/afternoon dosing. It’s not gospel, but it’s an easy, low-risk tweak.

What NMN probably doesn’t do (yet)

  • No proven disease prevention or lifespan extension in humans. The trials are short (6–12 weeks) and small.
  • Skeletal muscle NAD+ levels don’t always rise, even when blood NAD+ does. Biology is compartmentalized; blood ≠ muscle.

The regulatory wrinkle (US)

The FDA currently treats β-NMN as “under drug investigation” (e.g., MIB-626), which excludes it from being sold as a dietary supplement. Availability varies by country and retailer. (That’s regulation, not safety.)

If you’re NMN-curious, here’s a sane playbook

  • Who might feel it: 55+ adults, people with low fitness, or prediabetes (based on who improved in trials).
  • Dose used most often in studies: 250–600 mg/day. Some go higher short-term, but data are thin.
  • When to take: Try afternoon/evening for a month; track sleep/fatigue and a simple performance test (e.g., 30-second chair-stands).
  • Stacking? Tempting, but go one variable at a time. Add training, protein, and sleep consistency before piling on polyphenols “for synergy.”
  • Red flags: Pregnant/breastfeeding, active cancer, or complex meds—talk to your clinician first.

The scientist’s sticky note

  • Great signals: insulin sensitivity, chair-stand/grip/gait, ventilatory thresholds.
  • Known unknowns: long-term safety, optimal dose/timing, which tissues benefit, and whether higher NAD+ translates to fewer falls, fewer hospitalizations, or longer healthspan.
  • What would convince us: 12–24-month trials, n≥500, clinically meaningful endpoints (falls, MCI progression, VO₂max, HbA1c), and head-to-heads vs. NR/NAM.


“NMN looks safe short-term and reliably boosts blood NAD+; early human studies hint at better muscle function and insulin sensitivity—promising, but not a magic longevity pill.”


Song Q, Zhou X, Xu K, Liu S, Zhu X, Yang J. The Safety and Antiaging Effects of Nicotinamide Mononucleotide in Human Clinical Trials: an Update. Advances in Nutrition (2023). doi:10.1016/j.advnut.2023.08.008 (Open access)

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