Pilot study of H₂ therapy in Parkinson's disease: a randomized double-blind placebo-controlled trial
Yoritaka A, Takanashi M, Hirayama M, Nakahara T, Ohta S, Hattori N. · Movement Disorders. 2013;28(6):836–839.
Study at a glance
Human
Japanese patients with Parkinson's disease receiving stable levodopa and other antiparkinsonian medication.
Participants drank 1,000 mL/day of hydrogen-rich water in addition to their unchanged antiparkinsonian medication. · The article describes saturated hydrogen water at approximately 0.8 mmol/L, supplied as a total daily volume of 1,000 mL.
Forty-eight weeks, with assessments at baseline and during follow-up through week 48.
At week 48, total UPDRS change favored H₂ water: median −1.0 and mean −5.7±8.4 in the H₂ group versus median +4.5 and mean +4.1±9.2 with placebo (p<0.05). Six of nine H₂ participants improved and one was unchanged. The article states that additional analyses did not differ between groups. No participant changed levodopa or other antiparkinsonian medication; no adverse effect was attributed to H₂ water.
Very small pilot with 17 completers, one dropout, a single Japanese setting, large outcome variability and multiple analyses. The positive result was the total-UPDRS change; additional analyses were null. The trial predates a later multicenter randomized trial that did not confirm benefit. No dedicated funding or conflict-of-interest statement was identified in the checked article copy, so absence of funding or conflicts is not inferred.
What kind of evidence is this?
Human
Randomized double-blind placebo-controlled parallel-group pilot trial
Parkinson’s disease
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
Japanese patients with Parkinson's disease receiving stable levodopa and other antiparkinsonian medication.
18 participants were randomized, nine per group. One placebo participant discontinued because of pollakiuria, leaving H₂-water n=9 and placebo n=8 at week 48.
Forty-eight weeks, with assessments at baseline and during follow-up through week 48.
Participants drank 1,000 mL/day of hydrogen-rich water in addition to their unchanged antiparkinsonian medication.
H₂ dissolved in drinking water — H₂ only, not Brown's gas.
The article describes saturated hydrogen water at approximately 0.8 mmol/L, supplied as a total daily volume of 1,000 mL.
Pseudo/placebo water, 1,000 mL/day, with the same stable levodopa and antiparkinsonian-drug regimen.
Outcomes and reported result
Primary endpoint: change in total Unified Parkinson's Disease Rating Scale score from baseline to week 48; additional UPDRS analyses, medication stability, tolerability and adverse events.
At week 48, total UPDRS change favored H₂ water: median −1.0 and mean −5.7±8.4 in the H₂ group versus median +4.5 and mean +4.1±9.2 with placebo (p<0.05). Six of nine H₂ participants improved and one was unchanged. The article states that additional analyses did not differ between groups. No participant changed levodopa or other antiparkinsonian medication; no adverse effect was attributed to H₂ water.
The author-uploaded full-text copy, allocation and attrition, water dose and concentration, primary and additional results, medication stability and adverse-event reporting were checked together with PubMed and the publisher record.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Very small pilot with 17 completers, one dropout, a single Japanese setting, large outcome variability and multiple analyses. The positive result was the total-UPDRS change; additional analyses were null. The trial predates a later multicenter randomized trial that did not confirm benefit. No dedicated funding or conflict-of-interest statement was identified in the checked article copy, so absence of funding or conflicts is not inferred.
Levodopa-treated Japanese Parkinson's patients under this 48-week pilot protocol; the result is hypothesis-generating, not definitive evidence of disease modification.
Cochrane RoB 2 · parallel randomized trial · headline week-48 total UPDRS result
Some concerns — preliminary; independent reviewer pending
Small pilot, limited reporting of allocation concealment, one participant absent from the week-48 analysis, and no completed comparison with a prespecified analysis plan.
Some concerns — randomization is reported, but sequence generation and concealment are not fully documented in the extracted report. · Some concerns — placebo preparation and double blinding are described; adherence and protocol-deviation detail is limited. · Some concerns — 17 of 18 randomized participants were included at week 48; the impact of the missing result requires review. · Some concerns — UPDRS is appropriate, but assessor-blinding procedures need fuller verification. · Some concerns — multiple outcomes and time points; protocol and prespecified analysis have not been independently compared with the report.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 23400965 · DOI: 10.1002/mds.25375
The publisher page is paywalled; a free author-uploaded full-text copy is available on ResearchGate.
Author-uploaded full-text PDF, PubMed record and publisher metadata; full-text extraction checked 9 August 2026.
10 August 2026
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