Peripheral endothelial function can be improved by daily consumption of water containing over 7 ppm of dissolved hydrogen: A randomized controlled trial
Ishibashi T et al. · PLoS One. 2020;15(5):e0233484.
Study at a glance
Human
Healthy adult volunteers
500 mL/day high-concentration hydrogen-rich water · 7 ppm dissolved H₂; 3.5 mg H₂ in 500 mL water.
Single-dose measures through 24 hours and daily intake for 14 days
The article reports greater Ln_RHI improvement with H₂ water, including 22.2% at 24 hours and 25.4% after two weeks. This is a physiological surrogate outcome, not a cardiovascular-event endpoint.
Healthy-volunteer study with a surrogate vascular measure and short follow-up. The authors reported no specific funding.
What kind of evidence is this?
Human
Randomized placebo-controlled parallel trial
Cardiovascular and circulatory health
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
Healthy adult volunteers
68 randomized: H₂ water n=34 and placebo n=34
Single-dose measures through 24 hours and daily intake for 14 days
500 mL/day high-concentration hydrogen-rich water
H₂ dissolved in water — H₂ only, not Brown’s gas.
7 ppm dissolved H₂; 3.5 mg H₂ in 500 mL water.
500 mL/day nitrogen-containing placebo water
Outcomes and reported result
Reactive hyperemia index measured by peripheral arterial tonometry
The article reports greater Ln_RHI improvement with H₂ water, including 22.2% at 24 hours and 25.4% after two weeks. This is a physiological surrogate outcome, not a cardiovascular-event endpoint.
Dose, methods, full results, funding and competing-interest statements checked in the open-access full text; independent appraisal remains incomplete.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Healthy-volunteer study with a surrogate vascular measure and short follow-up. The authors reported no specific funding.
Healthy adults under the reported two-week drinking protocol; it does not establish prevention of cardiovascular events.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 32470022 · DOI: 10.1371/journal.pone.0233484
Open-access full text is available through PMC and PLOS.
Open-access PMC and publisher full texts plus PubMed bibliographic record.
10 August 2026
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