Gut bacteria convert glucocorticoids into progestins in the presence of hydrogen gas.
McCurry MD, D'Agostino GD, Walsh JT, Bisanz JE, Zalosnik I, Dong X, Morris DJ, Korzenik JR, Edlow AG, Balskus EP, Turnbaugh PJ, Huh JR, Devlin AS. · Cell. 2024;187:2717-2732.
Study at a glance
Preclinical
Gut bacterial cultures, human fecal-community experiments and mouse models.
Hydrogen-gas atmosphere or hydrogen-producing microbial conditions used to test steroid conversion. · Experimental H2 exposure varied by microbial assay; it was not administered as a patient treatment.
Experiment-specific microbial, ex-vivo and animal schedules.
Hydrogen availability enabled selected gut bacteria to convert glucocorticoids into progestins in the reported experimental systems.
This is mechanistic microbiome research, not evidence that administered hydrogen treats a disease.
What kind of evidence is this?
Preclinical
Mechanistic microbial, ex-vivo and animal study
Gastrointestinal health
Other forms
Positive mechanistic signal; no therapeutic inference.
Mechanistic microbial and metabolic outcomes; not a therapeutic clinical outcome.
Methods
Gut bacterial cultures, human fecal-community experiments and mouse models.
Multiple culture, ex-vivo and animal experiments; sample sizes were reported by experiment.
Experiment-specific microbial, ex-vivo and animal schedules.
Hydrogen-gas atmosphere or hydrogen-producing microbial conditions used to test steroid conversion.
Molecular H2 used as a microbial metabolic substrate; not a therapeutic inhalation intervention and not Brown's gas.
Experimental H2 exposure varied by microbial assay; it was not administered as a patient treatment.
Nitrogen or hydrogen-limited culture conditions and model-specific controls.
Outcomes and reported result
Microbial conversion of glucocorticoids to progestins, metabolites, gene/pathway activity and host-associated measures.
Hydrogen availability enabled selected gut bacteria to convert glucocorticoids into progestins in the reported experimental systems.
The full article, microbial mechanism, controls and animal and ex-vivo experiments were checked.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
This is mechanistic microbiome research, not evidence that administered hydrogen treats a disease.
The reported bacterial, fecal-community and mouse experimental systems.
SYRCLE animal-study tool — preliminary
Some concerns
Complex multi-model mechanistic study; animal allocation and blinding are not the primary basis of the microbial result.
Randomization/allocation reporting is limited · Blinding of personnel is unclear · Attrition is incompletely reported in places · Blinding of outcome assessors is unclear · No prospectively registered analysis plan identified
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 38795705 · DOI: 10.1016/j.cell.2024.05.005
Free full article in PubMed Central.
PubMed record and PubMed Central full text; extraction checked 9 August 2026.
10 August 2026
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