# Consumption of water containing over 3.5 mg of dissolved hydrogen could improve vascular endothelial function.
> 溶存水素濃度3.5mg以上の水摂取による血管内皮機能への影響：無作為化対照試験


## Abstract

This randomized controlled trial examined whether drinking water with a dissolved hydrogen concentration of 7 ppm (3.5 mg per 500 mL) could influence vascular endothelial function, assessed via flow-mediated dilation (FMD) of the brachial artery. Participants were randomly assigned to a high-H2 water group (8 males, 8 females) or a placebo group (10 males, 8 females). In the high-H2 group, FMD rose from a baseline of 6.80±1.96% to 7.64±1.68%, whereas the placebo group showed a decline from 8.07±2.41% to 6.87±2.94%. The change in FMD relative to baseline was significantly greater in the high-H2 group (P<0.05). These findings suggest that molecular hydrogen may preserve nitric oxide-dependent vasomotor responses by neutralizing shear stress-induced reactive oxygen species, particularly the hydroxyl radical, thereby supporting endothelial function.

### Mechanism

Molecular hydrogen selectively scavenges harmful reactive oxygen species, particularly the hydroxyl radical, thereby preserving nitric oxide bioavailability and maintaining endothelium-dependent vasodilation in conduit arteries.

## Bibliographic

- **Authors**: Sakai T, Sato B, Hara K, Hara Y, Naritomi Y, Koyanagi S, et al.
- **Journal**: Vasc Health Risk Manag
- **Year**: 2014
- **PMID**: [25378931](https://pubmed.ncbi.nlm.nih.gov/25378931/)
- **DOI**: [10.2147/VHRM.S68844](https://doi.org/10.2147/VHRM.S68844)
- **PMC**: [PMC4207582](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4207582/)
- **Study type**: human randomized controlled trial
- **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 25378931. https://h2-papers.org/en/papers/25378931
> **Source**: PubMed PMID [25378931](https://pubmed.ncbi.nlm.nih.gov/25378931/)