The effect of a low dose hydrogen-oxygen mixture inhalation in midlife/older adults with hypertension: A randomized, placebo-controlled trial
Liu B et al. · Front Pharmacol. 2022;13:1025487.
What kind of evidence is this?
Human
Randomized placebo-controlled parallel trial
Cardiovascular and circulatory health
Inhaled H₂
Not reported in this record.
Not reported in this record.
Methods at a glance
Adults aged 50–70 years with hypertension
60 randomized; 56 completed: H₂–O₂ n=29, air n=27
4 hours/day for 2 weeks
Hydrogen–oxygen mixture inhaled 4 hours/day
Brown’s gas / oxyhydrogen: 66% H₂ and 33% O₂ were co-delivered.
Total mixed-gas flow 30–60 mL/min. After dilution with room air, inspired H₂ was reported as approximately 0.2–0.4%.
19.8–39.6 mL/min H₂, calculated by Hydrogenology as 66% of the reported 30–60 mL/min mixed-gas flow.
9.9–19.8 mL/min O₂, calculated as 33% of the reported mixed-gas flow.
Air inhaled from a matched placebo device
Outcomes and reported result
Four-limb blood pressure, 24-hour ambulatory blood pressure and plasma hormones
Arm systolic pressure and nighttime ambulatory diastolic pressure decreased within the H₂–O₂ group. Several conclusions rely on within-group comparisons; the record does not treat these as proof of broad between-group superiority.
Gas composition, flow, main results, funding and conflict statement checked in the free full text; component flows are transparent calculations from the reported total.
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
Short 56-person completion sample, several within-group analyses and subgroup comparisons. Public Chinese grants funded the study; the device company was acknowledged, and authors declared no commercial or financial conflict.
Adults aged 50–70 with hypertension under this two-week protocol.
Not reported in this record.
Not reported in this record.
Not reported in this record.
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
PMID: 36278221 · DOI: 10.3389/fphar.2022.1025487
Open-access article.
Free full text on PMC and Frontiers; identifiers cross-checked in PubMed.
2026-08-10