Hydrogen nanobubble water reduces cochlear inflammation and oxidative stress in noise-induced hearing loss via the gut-inner ear axis
Li S, Yin J, Hu Y, Yuan C, Yu H, Zhang X, Yu S, Zhou Z, Jiang H, Xing Y, Xiong Y. · Ecotoxicology and Environmental Safety. 2026;319:120297.
Study at a glance
Hydrogen nanobubble water before and after loud noise reduced some later hearing-threshold changes in male mice. The day-one comparison was null, and several structural outcomes were unchanged. Exploratory gut and gene-expression findings do not establish the proposed mechanism or effectiveness in people.
Preclinical
Male C57BL/6J mice, six weeks old, and HEI-OC1 auditory cells. No human participants.
Ad libitum nanobubble water from one week before until one week after 8–16 kHz noise at 98 dB SPL for two hours; water replaced daily. Approximately 4 mL/mouse/day was estimated from cage-bottle weights, not individual intake. In cells, 20% nanobubble-water medium for one-hour pretreatment before 1.25 mM H₂O₂ for two hours; cytotoxicity tested at 0–35% over twelve hours. · Absolute dissolved H₂ concentration and individual oral dose were not verified. Mean nanobubble diameter 205.5 nm, zeta potential −16.5 mV, approximately fourteen billion/L. At three hours nineteen minutes, reported retention approximately 70% of initial H₂ versus 20% conventional water; initial absolute concentration is unknown.
One week before through one week after two-hour noise exposure; outcomes at days 1, 3 and 7.
Day 1 threshold shifts did not differ between nanobubble-water and noise groups. Day 3 shifts at 16 kHz: 15.67 ± 2.12 versus 37.67 ± 2.62 dB; at 22.6 kHz: 29.33 ± 2.58 versus 42.33 ± 2.76 dB. Day 7 shifts at 16, 22.6 and 32 kHz: 5.46 ± 2.74 versus 19.09 ± 4.81; 18.64 ± 2.87 versus 40.91 ± 2.77; 20.91 ± 4.85 versus 34.55 ± 3.47 dB. Wave-I impairment was reduced. Day-7 middle/basal synapses per inner hair cell: control 15.53 ± 0.44/10.01 ± 0.52; noise 11.17 ± 1.13/6.60 ± 0.49; nanobubble water 15.01 ± 0.38/9.37 ± 0.49. Basal node lengths: noise 1.86 ± 0.20 µm, nanobubble water 1.48 ± 0.05, control 1.54 ± 0.01; nanobubble/control difference nonsignificant. Vascular injury measures were attenuated. Hair-cell-loss comparisons and spiral-ganglion density did not show significant differences. Cell pretreatment improved injury-associated viability/ROS; nanobubble water alone at 0–35% showed no significant cytotoxicity. Main-text reports of supplementary S1 safety and S2 conventional-water comparisons were not independently checked against supplementary files.
Male animals, acute noise and pretreatment, short follow-up, small endpoint samples, many exploratory outcomes and no fully specified primary hierarchy. No measured absolute oral H₂ dose or inner-ear pharmacokinetics. Day-seven microbiome data and expression associations do not prove temporal precedence or a causal gut–inner-ear/NF-κB pathway. A specific nanobubble formulation is not interchangeable with ordinary hydrogen water.
What kind of evidence is this?
Preclinical
Randomized preclinical mouse experiment with HEI-OC1 cell-injury assays and exploratory cochlear transcriptomics/gut-microbiome analyses.
Published online 25 May 2026; issue 1 July 2026.
Other neurological conditions
H₂-rich water
Information not yet classified
Some editorial classification fields are still pending. The source-reported outcomes and result are shown below; Hydrogenology does not infer a positive or negative signal from prose automatically.
Methods
Male C57BL/6J mice, six weeks old, and HEI-OC1 auditory cells. No human participants.
92 mice total, not per arm. Groups: control, noise, noise + nanobubble water, noise + conventional hydrogen water, nanobubble water alone. Endpoint sizes: ABR n = 11; wave I n = 5; histology/synapse/node/vascular assays n = 3; microbiome n = 5 or 6; qPCR three biological replicates. Arm flow and attrition not fully specified.
One week before through one week after two-hour noise exposure; outcomes at days 1, 3 and 7.
Ad libitum nanobubble water from one week before until one week after 8–16 kHz noise at 98 dB SPL for two hours; water replaced daily. Approximately 4 mL/mouse/day was estimated from cage-bottle weights, not individual intake. In cells, 20% nanobubble-water medium for one-hour pretreatment before 1.25 mM H₂O₂ for two hours; cytotoxicity tested at 0–35% over twelve hours.
Hydrogen-rich water
Absolute dissolved H₂ concentration and individual oral dose were not verified. Mean nanobubble diameter 205.5 nm, zeta potential −16.5 mV, approximately fourteen billion/L. At three hours nineteen minutes, reported retention approximately 70% of initial H₂ versus 20% conventional water; initial absolute concentration is unknown.
Noise-only ordinary water, conventional hydrogen water, unexposed control and nanobubble-water-only control.
Outcomes and reported result
Auditory brainstem responses, wave I, cochlear cells/synapses/nodes/vascular measures, oxidative/inflammatory markers, cell assays and exploratory microbiome/transcriptome outcomes.
Day 1 threshold shifts did not differ between nanobubble-water and noise groups. Day 3 shifts at 16 kHz: 15.67 ± 2.12 versus 37.67 ± 2.62 dB; at 22.6 kHz: 29.33 ± 2.58 versus 42.33 ± 2.76 dB. Day 7 shifts at 16, 22.6 and 32 kHz: 5.46 ± 2.74 versus 19.09 ± 4.81; 18.64 ± 2.87 versus 40.91 ± 2.77; 20.91 ± 4.85 versus 34.55 ± 3.47 dB. Wave-I impairment was reduced. Day-7 middle/basal synapses per inner hair cell: control 15.53 ± 0.44/10.01 ± 0.52; noise 11.17 ± 1.13/6.60 ± 0.49; nanobubble water 15.01 ± 0.38/9.37 ± 0.49. Basal node lengths: noise 1.86 ± 0.20 µm, nanobubble water 1.48 ± 0.05, control 1.54 ± 0.01; nanobubble/control difference nonsignificant. Vascular injury measures were attenuated. Hair-cell-loss comparisons and spiral-ganglion density did not show significant differences. Cell pretreatment improved injury-associated viability/ROS; nanobubble water alone at 0–35% showed no significant cytotoxicity. Main-text reports of supplementary S1 safety and S2 conventional-water comparisons were not independently checked against supplementary files.
Main-text methods, results, limitations and declarations were reviewed. Source versions, missing information and conflicting findings are stated in this record.
Short animal/cell observations do not establish clinical safety. Main-text supplementary safety descriptions were not independently verified; comprehensive adverse-event counts not identified.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Male animals, acute noise and pretreatment, short follow-up, small endpoint samples, many exploratory outcomes and no fully specified primary hierarchy. No measured absolute oral H₂ dose or inner-ear pharmacokinetics. Day-seven microbiome data and expression associations do not prove temporal precedence or a causal gut–inner-ear/NF-κB pathway. A specific nanobubble formulation is not interchangeable with ordinary hydrogen water.
Limited to the population/model and protocol described above. These findings do not provide a treatment, concentration or device recommendation.
NSFC 82260224, 82471183, 82171116, 52276158; Central Universities BYG2025QNB28; Shanghai Sixth Hospital ynms202302; Jiangxi Natural Science 20242BAB25491; Jiangxi Key Clinical Specialty 202382; Jiangxi Education GJJ2401814.
Authors declare no known competing financial or personal interests. Equipment provided by Shanghai Jiao Tong Sixth Hospital ENT department.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 42184652 · DOI: 10.1016/j.ecoenv.2026.120297
Complete main publisher text read across complementary indexed views: Methods 2.1–2.16, Results 3.1–3.7, Table 1, main figure captions, discussion and declarations. PDF, actual figure images and supplementary files were not read; supplement-dependent findings are identified as main-text reports.
AI-assisted editorial review of the available main full text, 29 October 2026. No independent clinical or statistical assessment has been performed.
Main publisher text: Introduction; Methods 2.1–2.16; Results 3.1–3.7; Table 1; Figures 1–7 captions and main-text numerical findings; Discussion; Conclusion; ethics, funding, competing interests and acknowledgments. Images and supplements not read.
AI-assisted editorial review of the available main full text, 29 October 2026. Complete main publisher text read across complementary indexed views: Methods 2.1–2.16, Results 3.1–3.7, Table 1, main figure captions, discussion and declarations. PDF, actual figure images and supplementary files were not read; supplement-dependent findings are identified as main-text reports.
Animal ethics Shanghai Sixth People’s Hospital 2022–0411.
29 October 2026
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