Acute hydrogen-rich water ingestion stimulates cardiac autonomic activity in healthy females
Botek M, Sládečková B, Krejčí J, Pluháček F, Najmanová E. · Acta Gymnica. 2021;51:e2021.009.
What kind of evidence is this?
Human
Randomized double-blind placebo-controlled crossover trial
Cardiovascular and circulatory health
H₂-rich water
Mixed, time-point-specific exploratory signal.
Short-term autonomic surrogate outcomes.
Methods at a glance
Healthy young women.
14 participants.
Acute intake with 50 minutes of seated monitoring.
1,260 mL hydrogen-rich water consumed within 15 minutes.
H₂ dissolved in drinking water.
0.9 ppm dissolved H₂.
Not applicable — drinking water.
No oxygen was co-delivered.
1,260 mL placebo water containing 0 ppm H₂.
Outcomes and reported result
Heart-rate-variability time-domain measures and heart rate.
Some HRV comparisons differed at selected time points, while several other comparisons were null.
The full article methods, intervention, outcomes, positive and null findings, funding and conflict statements were checked.
A reported association, difference or mechanism is not automatically a clinical benefit. Null findings, outcome type, study design and precision all matter.
Cautions and applicability
Very small acute crossover study, many time-point comparisons and surrogate outcomes only.
Healthy young women during short seated monitoring.
Cochrane RoB 2 — preliminary
Some concerns
Randomization and blinding were reported, but the small sample and multiple time-point analyses create imprecision and selective-reporting concerns.
Random sequence reported or described · Allocation concealment not fully established · Deviations and co-interventions checked · Outcome measurement checked by endpoint · No outcome-level protocol comparison completed
No single-study GRADE certainty rating is assigned. Certainty is assessed by important outcome across a complete eligible evidence set, not by attaching a final grade to one source.
Sources and record status
DOI: 10.5507/ag.2021.009 · DOI: 10.5507/ag.2021.009
A free publisher or repository full article was checked.
Publisher or repository full article and bibliographic record; checked 10 August 2026.
2026-08-10