High-flow hydrogen inhalation might suppresses the immune function of middle-aged participants: a self-controlled study
Chen JB, Kong XF, Mu F. · Medical Gas Research. 2021;11(1):12–17.
Study at a glance
Human
Twenty adults aged 31–60 years without malignant tumors or uncontrolled severe disease.
Nasal-tube inhalation from an AMS-H-03 generator at a total mixture flow of 3 L/min for 2 or 4 hours/day. · 66.7% H₂ and 33.3% O₂; total flow 3,000 mL/min.
2 or 4 hours/day for 2 weeks.
Most immune-cell indicators and major T-cell subsets did not change. Several small anti-infection and antitumor subtypes decreased after two weeks; the authors interpreted these shifts as possible immune suppression/adverse response in healthy participants. The study did not test clinical illness, infection or cancer outcomes.
Only 20 participants, no control or sham, two weeks of follow-up and numerous immune subsets. The authors reported no financial support and no conflicts, while thanking the hydrogen-inhalation site and staff. Immune-cell proportion changes are surrogate findings, not demonstrated clinical harm or benefit.
What kind of evidence is this?
Human
Uncontrolled self-comparison study with randomized 2-hour and 4-hour exposure groups
Immune and inflammatory conditions
Inhaled H₂
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
Twenty adults aged 31–60 years without malignant tumors or uncontrolled severe disease.
20 participants randomized to 2 hours/day (n=10) or 4 hours/day (n=10).
2 or 4 hours/day for 2 weeks.
Nasal-tube inhalation from an AMS-H-03 generator at a total mixture flow of 3 L/min for 2 or 4 hours/day.
Brown's gas / oxyhydrogen — H₂ and O₂ co-delivered, not H₂ alone.
66.7% H₂ and 33.3% O₂; total flow 3,000 mL/min.
Approximately 2,000 mL/min H₂, calculated from the reported 66.7% of 3,000 mL/min.
Approximately 1,000 mL/min O₂ co-delivered, calculated from the reported 33.3% of 3,000 mL/min.
Each participant's pre-treatment values; no sham-gas or untreated control.
Outcomes and reported result
Peripheral-blood T, B, natural-killer, natural-killer-T and gamma-delta-T cell subsets by flow cytometry.
Most immune-cell indicators and major T-cell subsets did not change. Several small anti-infection and antitumor subtypes decreased after two weeks; the authors interpreted these shifts as possible immune suppression/adverse response in healthy participants. The study did not test clinical illness, infection or cancer outcomes.
The complete PMC article, allocation, gas composition, total and calculated component flows, all immune tables, acknowledgements, funding and conflicts were checked; null findings are included.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Only 20 participants, no control or sham, two weeks of follow-up and numerous immune subsets. The authors reported no financial support and no conflicts, while thanking the hydrogen-inhalation site and staff. Immune-cell proportion changes are surrogate findings, not demonstrated clinical harm or benefit.
Middle-aged adults under this short high-flow protocol; not a clinical efficacy study.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 33642332 · DOI: 10.4103/2045-9912.310054
Free full article on PubMed Central.
PMC full article and PubMed record; full-text and article-status check completed 8 August 2026.
10 August 2026
Help people check the facts before they buy.
Hydrogenology keeps 665 source-checked records accessible without advertising or product promotion.
Help us correct the recordReport a discrepancy
Send the exact difference between this page and the linked source. The study reference is attached automatically.