# Molecular hydrogen as a novel antioxidant: overview of the advantages of hydrogen for medical applications.
> 医療応用における分子状水素の抗酸化物質としての優位性：概説


## Abstract

Molecular hydrogen (H2), once considered biologically inert in mammalian systems, was shown to react with highly reactive oxidants including hydroxyl radicals and peroxynitrite within cells. A key advantage of H2 is its selective reactivity: it does not interfere with normal metabolic redox processes or reactive oxygen species signaling, suggesting a low adverse-effect profile. Multiple administration routes have been identified, including gas inhalation, oral intake of H2-dissolved water, intravenous or intraperitoneal H2-dissolved saline, bathing, and ocular application. H2 diffuses rapidly across tissues and cellular membranes. Beyond direct scavenging of reactive oxidants, H2 modulates gene expression to exert anti-inflammatory, antiallergic, and antiapoptotic effects, and appears to stimulate energy metabolism. This review summarizes evidence from animal models and clinical investigations supporting the broad potential of H2 across numerous disease contexts.

### Mechanism

H2 directly neutralizes hydroxyl radicals and peroxynitrite, and indirectly reduces oxidative stress by modulating gene expression, thereby producing anti-inflammatory, antiallergic, and antiapoptotic effects while also stimulating energy metabolism.

## Bibliographic

- **Authors**: Ohta S
- **Journal**: Methods Enzymol
- **Year**: 2015
- **PMID**: [25747486](https://pubmed.ncbi.nlm.nih.gov/25747486/)
- **DOI**: [10.1016/bs.mie.2014.11.038](https://doi.org/10.1016/bs.mie.2014.11.038)
- **Study type**: review
- **Delivery route**: mixed routes
- **Effect reported**: not assessed

## Delivery context

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

## Safety notes

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; 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 25747486. https://h2-papers.org/en/papers/25747486
> **Source**: PubMed PMID [25747486](https://pubmed.ncbi.nlm.nih.gov/25747486/)