Effectiveness of hydrogen rich water on antioxidant status of subjects with potential metabolic syndrome—an open label pilot study
Nakao A et al. · J Clin Biochem Nutr. 2010;46(2):140–149.
Study at a glance
Human
Adults aged 40 or older with potential metabolic syndrome
Participants drank 300–400 mL from each of five prepared bottles daily: 1.5–2.0 L/day total · 0.55–0.65 mM dissolved H₂, generated with magnesium sticks; reported pH 7.9–8.1.
8 weeks
From baseline, the paper reports SOD increased 39% and urinary TBARS decreased 43% at week 8 (both p<0.05); HDL increased 8% and total cholesterol/HDL ratio decreased 13% at week 4; fasting glucose did not change.
Open-label, single-site pilot with 20 participants and no placebo comparator; within-group changes and mainly laboratory outcomes are vulnerable to bias.
What kind of evidence is this?
Human
Open-label single-site pilot study
Metabolic and lipid 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
Adults aged 40 or older with potential metabolic syndrome
20 participants
8 weeks
Participants drank 300–400 mL from each of five prepared bottles daily: 1.5–2.0 L/day total
H₂ dissolved in water — H₂ only, not Brown’s gas.
0.55–0.65 mM dissolved H₂, generated with magnesium sticks; reported pH 7.9–8.1.
No placebo comparator
Outcomes and reported result
Oxidative-stress, lipid, glucose and safety measures
From baseline, the paper reports SOD increased 39% and urinary TBARS decreased 43% at week 8 (both p<0.05); HDL increased 8% and total cholesterol/HDL ratio decreased 13% at week 4; fasting glucose did not change.
Methods and principal results checked in the free full text; independent risk-of-bias appraisal remains incomplete.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Open-label, single-site pilot with 20 participants and no placebo comparator; within-group changes and mainly laboratory outcomes are vulnerable to bias.
Adults aged 40 or older described as having potential metabolic syndrome in this study.
Cochrane guidance for uncontrolled before-after studies · biomarker changes
High risk for causal interpretation — preliminary
Open-label single-arm study with no concurrent comparator. Time trends, behavior changes, regression to the mean and selective reporting cannot be separated from an intervention effect.
High risk — no random allocation or comparator. · High risk — participants and investigators knew the intervention; co-interventions and behavioral changes are difficult to exclude. · Some concerns — full-text follow-up is reported, but attrition handling requires structured verification. · Some concerns — laboratory measures are objective, but collection and analysis were not blinded by a comparator design. · Some concerns — many biomarkers and time points; no prespecified public analysis plan was identified.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 20216947 · DOI: 10.3164/jcbn.09-100
Open-access full text is available through PMC and J-STAGE.
Free full text on PMC; bibliographic identifiers cross-checked in PubMed.
10 August 2026
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