# Effects of Hydrogen-Rich Water on Growth, Redox Homeostasis and Hormonal, Histological and Immune Systems in Rats Exposed to High Cage Density Stress.
> 高密度飼育ストレス下のラットにおける水素水摂取が発育・酸化還元恒常性・ホルモン・組織・免疫系に及ぼす影響


## Abstract

This animal study examined the effects of hydrogen-rich water (HRW) consumed ad libitum over 3 months in rats subjected to restricted housing conditions (half the standard area). Eight groups of male and female rats were assigned to control, HRW-only, stress-only, and stress-plus-HRW conditions. Body weight gain was greater in HRW-receiving animals than in the stress-only group. Biochemical assessment revealed that oxidative markers, including malondialdehyde and disulfide ratios, were lower in the stress-plus-HRW group relative to the stress-only group. Stress-induced hormonal changes—elevated FT4, cortisol, and calcium alongside reduced TSH—were attenuated by HRW intake. Glutathione and total thiol levels, as well as SOD-2 immunoreactivity and histopathological findings, further supported a protective redox effect. These results suggest that HRW consumption may mitigate physiological dysregulation arising from chronic crowding stress in rodents.

### Mechanism

HRW appears to reduce oxidative burden by lowering malondialdehyde, preserving glutathione, and improving thiol/disulfide ratios, which may secondarily suppress stress-hormone dysregulation including elevated cortisol and FT4.

## Bibliographic

- **Authors**: Boğa Kuru B, Makav M, Kuru M, Aras ŞY, Karadağ Sarı E, Bulut M, et al.
- **Journal**: Vet Med Sci
- **Year**: 2025
- **PMID**: [40104881](https://pubmed.ncbi.nlm.nih.gov/40104881/)
- **DOI**: [10.1002/vms3.70305](https://doi.org/10.1002/vms3.70305)
- **PMC**: [PMC11920740](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11920740/)
- **Study type**: animal study
- **Delivery route**: hydrogen-rich water
- **Effect reported**: positive

## Delivery context

Hydrogen-rich water is a low-risk delivery route, but the achievable systemic hydrogen dose is bounded. For clinical applications, inhalation is the most efficient route; inhalation, however, carries explosion risk, and concentration matters (empirical LFL of 10% applies to inhalation environments; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

## Safety notes

Hydrogen-rich water is a low-risk delivery route, but the achievable systemic hydrogen dose is bounded. For clinical applications, inhalation is the most efficient route; inhalation, however, carries explosion risk, and concentration matters (empirical LFL of 10% applies to inhalation environments; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 40104881. https://h2-papers.org/en/papers/40104881
> **Source**: PubMed PMID [40104881](https://pubmed.ncbi.nlm.nih.gov/40104881/)