Tier 3 — preclinical

Oral Supplementation of Nicotinamide Mononucleotide (NMN) Improves Hair Quality and Subjective Perception of Hair Appearance in Middle-Aged Women

Shuichi Fukumoto, Maiko Ito, Hiroyo Kunitomo, Takeshi Hataoka, Takuya Chiba, Osamu Nureki, Takahiro Fujimoto
Cosmetics 2025 12, 204

Bibliography

DOI
10.3390/cosmetics12050204
Funding
Funded by Mitsubishi Corporation Life Sciences Limited under collaborative research agreements with Clinic F (LS24002541) and Waseda University (LS24003708); the paper reports no additional external funding.
Competing interests
Shuichi Fukumoto and Hiroyo Kunitomo are employees of Mitsubishi Corporation Life Sciences Limited (MCLS), which funded the research. Takuya Chiba and Maiko Ito at Waseda University received research grants from MCLS. Takahiro Fujimoto received speaking fees from MCLS, and Takeshi Hataoka contributed as a researcher and expert. Osamu Nureki declared no conflicts.

Study snapshot

DesignOpen-label, single-arm, pre-post intervention study.
Model15 healthy Japanese women aged 40-50 years with hair concerns such as thinning, reduced elasticity or reduced gloss.
Samplen=15; hair-diameter analysis used 13 participants after exclusion of two statistical outliers.
InterventionTorula yeast-fermented NMN 500 mg/day (12 tablets) orally for 12 weeks, generally taken in the morning around breakfast and before lunch.
Duration12 weeks.
EndpointsTrichoScan total, anagen, vellus and terminal hair density; Three-day hair elongation density after shaving; Hair-shaft diameter by scanning electron microscopy; Hair cuticle appearance; Hair metabolomics by CE-TOFMS; Hair steroid hormone concentrations; Visual analog scale ratings for fatigue and hair appearance

What the study showed, in plain terms

This exploratory study followed 15 middle-aged women before and after 12 weeks of 500 mg/day NMN. There was no placebo group, so every result is a within-person pre/post comparison rather than a controlled estimate of NMN's effect.

Anagen hair elongation density and terminal-hair elongation density increased, and average hair-shaft diameter increased from 75.3 to 78.8 micrometres in the 13-person diameter analysis. Subjective ratings for several hair characteristics also improved.

The picture is not uniformly positive: total, vellus and terminal hair density measured at the fixed time point decreased after supplementation. The study's design, small sample and industry funding make the findings hypothesis-generating and in need of controlled replication.

Key findings

  • Anagen hair elongation density over three days increased from 55.9 to 87.7 hairs/cm² (p=0.03).
  • Terminal-hair elongation density increased from 38.6 to 66.2 hairs/cm² (p<0.01), while vellus-hair elongation density did not significantly change.
  • Mean hair-shaft diameter increased from 75.3 to 78.8 µm in the 13 participants included in the SEM analysis (p<0.01); 11 of 13 showed an increase.
  • Total hair density decreased from 190.8 to 167.9 hairs/cm² (p<0.01), and both vellus and terminal density also decreased, complicating a simple 'more hair' interpretation.
  • Metabolomic profiles changed in amino-acid and energy-related pathways, while hair hormone concentrations showed no marked changes.
  • Participants reported improvements in several subjective hair characteristics and reductions in fatigue/perceived hair loss, but these ratings were unblinded and uncontrolled.

What this study can and cannot tell us

The study had no placebo or comparator arm, making regression to the mean, seasonal effects, measurement variability and expectancy effects plausible alternative explanations.

Only 15 women were enrolled, and two were excluded as statistical outliers from the hair-diameter analysis. The population was limited to Japanese women aged 40-50 years.

The paper notes variability in hormonal assessment, and the sponsor had extensive involvement through funding and employee authorship. Larger blinded, placebo-controlled studies are needed before causal claims are warranted.

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