What large randomized controlled trials of hydrogen-rich water are currently registered or recruiting?

1. What the published randomized trials look like: modest size, varied targets

The best‑known randomized trials of HRW are generally small to moderate in size and target metabolic, aging, liver, or inflammatory outcomes — for example, a 24‑week, double‑blind RCT in 60 adults with metabolic syndrome (n = 60) and a 6‑month randomized pilot in older adults (n = 40) are among the larger published trials in the literature provided ^{[1] [4] [5]}.

2. Systematic reviews: pooled evidence but not one big trial

Meta‑analyses and systematic reviews have identified multiple RCTs but emphasize small individual study sizes; one systematic review and meta‑analysis included eight randomized controlled trials totaling 357 patients with metabolic disorders, underlining that the field’s “large” evidence base is a pooled collection of small RCTs rather than one large, definitive trial ^[2].

3. Recent randomized trials and pilot RCTs (2020–2025)

Several randomized, double‑blind, placebo‑controlled trials appeared between 2020 and 2025 including a 4‑week trial in healthy adults (n ≈ 38) testing inflammatory and apoptotic markers (1.5 L/day HRW vs plain water) and later RCTs addressing NAFLD, aging biomarkers, and metabolic syndrome; an 8‑week pilot in elite athletes and an 8‑week trial in chronic high‑altitude disease were reported or published as conducted in 2024–2025 ^{[6] [1] [4] [7]}.

4. Registered protocols and recruiting studies cited in the reporting

The supplied sources include at least one registered and peer‑published protocol for a randomized, double‑blind, placebo‑controlled trial of HRW to reduce acute and residual fatigue after simulated football matches, with data collection planned around August 2025 (JMIR Research Protocols) — this indicates ongoing trial activity but is a protocol rather than evidence of a large, actively recruiting multicenter RCT ^{[3] [8]}. Another recent randomized trial (HYDRAPPET) evaluating 8‑week HRW in people with obesity reported 35 randomized participants, again underscoring modest sample sizes ^{[9] [10]}.

5. What counts as “large” and what the reporting does not show

None of the provided sources documents a currently registered, recruiting RCT that meets a conventional definition of “large” (for example, several hundred to thousands of randomized participants) — the literature instead shows multiple small‑to‑moderate RCTs and protocols, and pooled analyses that aggregate these smaller trials to reach hundreds of participants total ^{[2] [1] [4]}. The supplied material does not include ClinicalTrials.gov or WHO registry entries indicating a high‑enrollment, actively recruiting HRW trial, so confirmation of such a trial cannot be made from these sources alone ^{[3] [8]}.

6. Context, caveats and competing agendas

Authors and reviews frequently note the safety profile and biological plausibility of H2 interventions, but they also flag limitations: heterogenous dosing, short durations, pilot designs, and small samples limit generalizability and make meta‑analytic pooling necessary to detect signals ^{[11] [2]}. Commercial interest in HRW products is an implicit driver of research and media attention — the trend‑language around “hydrogen water” in reviews reflects both scientific curiosity and wellness market dynamics ^[12].

7. Bottom line for readers and researchers

The current evidence base consists of multiple small to moderate RCTs and emerging protocols rather than a single large, multicenter, recruiting randomized trial; the sources here confirm active research (published RCTs and 2024–2025 protocols) but do not document any large, registered, recruiting trial meeting a high‑enrollment threshold in the material provided ^{[1] [3] [2]}. To identify any large, actively recruiting RCTs beyond these reports would require searching clinical trial registries (ClinicalTrials.gov, EU‑CTR, WHO ICTRP) or contacting trial sponsors directly, steps not covered in the supplied sources.