Molecular Hydrogen Attenuates Chronic Inflammation and Delays the Onset of Ultraviolet B-Induced Skin Carcinogenesis in Mice
Hori F et al. · Int J Mol Sci. 2026;27(2):635.
What kind of evidence is this?
Preclinical
Two independently replicated controlled mouse UVB-carcinogenesis series
Cancer research
Inhaled H₂
Not reported in this record.
Not reported in this record.
Methods at a glance
Male HR-1 hairless mice exposed to chronic dorsal UVB
Two independent mouse series; the pathological table reports 14 control and 12 H₂-treated mice, while tissue comparisons commonly report n=4–7/group
UVB three times/week for 20 weeks plus 10 weeks of observation
Continuous 2% H₂ inhalation plus hydrogen-rich drinking water during UVB exposure and follow-up
H₂ diluted in air plus H₂ dissolved in water — not Brown’s gas.
2% inhaled H₂ plus drinking water confirmed at ≥0.8 mM dissolved H₂.
Not reported — the complete article gives chamber concentration but no total gas flow, so H₂ flow in mL/min cannot be calculated.
No supplemental O₂ was reported; O₂ came from normal air. O₂ flow in mL/min was not reported.
Normal air plus dehydrogenated water under the same UVB schedule
Outcomes and reported result
Papilloma and squamous-cell-carcinoma onset, tumor counts, survival, CPD, inflammation, redox and signaling markers
Papilloma onset was delayed and cumulative tumors were lower in both series. Survival and squamous-cell-carcinoma delay reached significance in only one series each; CPD levels were unchanged.
The complete open-access article was checked for both H₂ routes, cohort and assay sizes, positive and null results, limitations, funding and conflicts. Total chamber-gas flow is not reported.
A reported association, difference or mechanism is not automatically a clinical benefit. Null findings, outcome type, study design and precision all matter.
Cautions and applicability
Preclinical carcinogenesis model, combined inhalation and drinking-water intervention, some findings replicated incompletely and no human participants. The water was supplied in kind by MiZ.
UVB-induced skin carcinogenesis in hairless mice, not cancer prevention in people.
Not reported in this record.
Not reported in this record.
Not reported in this record.
No single-study GRADE certainty rating is assigned. Certainty is assessed by important outcome across a complete eligible evidence set, not by attaching a final grade to one source.
Sources and record status
PMID: 41596287 · DOI: 10.3390/ijms27020635
Open-access full text is available through PMC.
Open-access PMC full text and PubMed record.
2026-08-10