Research library · Human trials
Hydrogen water research library: every human drinking-water trial in one table
Last reviewed October 2026 · Aloha H2 Editorial
Every human trial of drinking hydrogen-rich water that we could locate, one row each, including the ones that found nothing. 26 trials across 5 topics; 3 reported no significant effect and 10 were mixed. Each row links to the original paper so you can check our summary against the source.
How this library was built
We searched PubMed and PMC for human trials where participants drank hydrogen-rich water or dissolved hydrogen tablets, and excluded animal studies, cell studies, hydrogen inhalation, hydrogen saline injection and hydrogen baths. We recorded the design exactly as the authors describe it, so an open-label study with no placebo is labelled that way even when the result looks good. Where the published summary and the full result differ, we follow the full paper. Sample sizes are the number of participants who completed the protocol where that figure is reported.
If you know of a human drinking-water trial we have missed, email everything@8eight8.net with the citation and we will add it, whatever it found.
Metabolic health — 5 trials
| Year | Study | Participants | Design | Dose & duration | What was measured | Result |
|---|---|---|---|---|---|---|
| 2008 | Kajiyama S et al. Nutrition Research View study | 36 adults with type 2 diabetes or impaired glucose tolerance | Randomized, double-blind, placebo-controlled crossover | 900 mL/day hydrogen-rich water, 8 weeks | LDL, oxidized LDL, glucose tolerance, urinary 8-isoprostanes | MixedLower modified LDL and small-dense LDL, lower urinary oxidative markers; glucose tolerance normalized in 4 of 6 IGT participants. No change in fasting glucose or HbA1c. |
| 2010 | Nakao A et al. Journal of Clinical Biochemistry and Nutrition View study | 20 adults with potential metabolic syndrome | Open-label pilot, no placebo | 1.5–2 L/day, 8 weeks | SOD, TBARS, HDL, total cholesterol | PositiveUrinary TBARS down 43%, SOD up 39%, HDL up 8%, total cholesterol/HDL ratio down 13%. Uncontrolled design. |
| 2013 | Song G et al. Journal of Lipid Research View study | 20 adults with potential metabolic syndrome | Open-label, no placebo | 0.9–1.0 L/day, 10 weeks | Serum lipids, HDL function, oxidative stress | PositiveLower total and LDL cholesterol and apoB; improved HDL function markers; lower TBARS. Uncontrolled design. |
| 2018 | Korovljev D et al. Irish Journal of Medical Science View study | 10 middle-aged overweight women | Randomized, double-blind, placebo-controlled crossover | Hydrogen-generating tablets (12 mg H₂/day), 4 weeks | Body composition, fasting glucose/insulin, lipids | MixedLower body-fat percentage and arm fat index, lower fasting insulin; no change in lipids or glucose. Very small sample. |
| 2020 | LeBaron TW et al. Diabetes, Metabolic Syndrome and Obesity View study | 60 adults with metabolic syndrome | Randomized, double-blind, placebo-controlled | High-concentration hydrogen-rich water from tablets (>5.5 mmol H₂/day), 24 weeks | BMI, waist-to-hip ratio, lipids, fasting glucose, HbA1c, inflammatory markers | PositiveLower cholesterol, fasting glucose and HbA1c; lower TNF-α and IL-6; small reductions in BMI and waist-to-hip ratio. |
Exercise and recovery — 9 trials
| Year | Study | Participants | Design | Dose & duration | What was measured | Result |
|---|---|---|---|---|---|---|
| 2012 | Aoki K et al. Medical Gas Research View study | 10 male soccer players | Randomized, double-blind, placebo-controlled crossover | 1.5 L hydrogen-rich water before exercise, single day | Blood lactate, peak torque, oxidative stress | PositiveLower blood lactate after exercise and no decline in peak torque vs placebo; no change in oxidative stress markers. |
| 2014 | Ostojic SM, Stojanovic MD Research in Sports Medicine View study | 52 physically active men | Randomized, double-blind, placebo-controlled | 2 L/day, 14 days | Fasting arterial blood pH, post-exercise pH | PositiveHigher fasting and post-exercise blood pH (alkalizing effect); no performance outcome measured. |
| 2014 | Ostojic SM et al. Postgraduate Medicine View study | 36 athletes with soft-tissue injuries | Randomized, single-blind, placebo-controlled | Oral hydrogen tablets ± topical hydrogen, 2 weeks | Plasma viscosity, CRP, range of motion, recovery | MixedFaster return of joint range of motion and lower plasma viscosity in hydrogen groups; CRP not significantly different. |
| 2018 | Da Ponte A et al. Journal of Sports Medicine and Physical Fitness View study | 8 trained cyclists | Randomized, double-blind, placebo-controlled crossover | 2 L/day, 2 weeks | Sprint peak power, lactate, perceived exertion | MixedHigher peak power in later sprints and lower perceived exertion; no change in lactate. Very small sample. |
| 2019 | Botek M et al. International Journal of Sports Medicine View study | 12 healthy men | Randomized, double-blind, placebo-controlled crossover | 600 mL hydrogen-rich water 30 min before incremental cycling | Ventilation, lactate, heart rate, perceived exertion | PositiveLower lactate and perceived exertion at the higher workloads; no difference at low intensity. |
| 2019 | LeBaron TW et al. Journal of Lifestyle Medicine View study | 19 mid-age adults | Randomized, double-blind, placebo-controlled crossover pilot | Hydrogen tablets in water, acute dose | Heart rate, perceived exertion, blood lactate during submaximal exercise | MixedLower heart rate and perceived exertion at submaximal workloads; lactate unchanged. |
| 2019 | Mikami T et al. Canadian Journal of Physiology and Pharmacology View study | 99 healthy adults | Randomized, double-blind, placebo-controlled | 500 mL hydrogen water before cycling | Endurance time, psychometric fatigue | PositiveLonger endurance and lower fatigue scores vs placebo in the less-trained subgroup; smaller effect in trained participants. |
| 2020 | Dobashi S et al. Medical Gas Research View study | 8 physically active men | Randomized, double-blind, placebo-controlled crossover | Hydrogen-rich water across 3 consecutive days of hard exercise | Blood antioxidant capacity, oxidative stress, performance | MixedPrevented the drop in total antioxidant capacity seen with placebo; no difference in performance or soreness. |
| 2022 | Botek M et al. Journal of Strength and Conditioning Research View study | 12 trained men | Randomized, double-blind, placebo-controlled crossover | 1,260 mL/day for 3 days + 1,260 mL on test day, resistance training | Lactate, countermovement jump, muscle soreness | PositiveLower lactate at 30 min, better jump height at 30 min, lower soreness at 24 h; differences gone at 48 h. |
Inflammation and oxidative stress — 5 trials
| Year | Study | Participants | Design | Dose & duration | What was measured | Result |
|---|---|---|---|---|---|---|
| 2012 | Ishibashi T et al. Medical Gas Research View study | 20 patients with rheumatoid arthritis | Open-label, no placebo | 530 mL/day hydrogen-rich water, 4 weeks ×2 | Urinary 8-OHdG, DAS28 disease activity | PositiveLower urinary 8-OHdG and DAS28; 4 of 5 early-stage patients reached remission. Uncontrolled design. |
| 2013 | Xia C et al. Clinical and Translational Science View study | 60 patients with chronic hepatitis B | Randomized, controlled | 1,200–1,800 mL/day, 6 weeks | Oxidative stress markers, liver function, HBV DNA | Null / no effectLower oxidative stress markers; no significant change in liver function or viral load. |
| 2011 | Kang KM et al. Medical Gas Research View study | 49 patients receiving radiotherapy for liver tumors | Randomized, placebo-controlled | 1.5–2 L/day, 6 weeks | Quality of life, oxidative markers, tumor response | PositiveBetter quality-of-life scores and lower oxidative markers; tumor response to radiotherapy unaffected. |
| 2020 | Sim M et al. Scientific Reports View study | 41 healthy adults aged 20–59 | Randomized, double-blind, placebo-controlled | 1.5 L/day, 4 weeks | Oxidative stress, antioxidant capacity, inflammatory cytokines, cell apoptosis | MixedHigher antioxidant capacity and lower inflammatory responses, mainly in participants aged 30 and over; no significant effect in the youngest participants. |
| 2021 | Zanini D et al. Experimental Gerontology View study | 40 adults aged 70 and over | Randomized, double-blind, placebo-controlled pilot | 0.5 L/day hydrogen-rich water, 6 months | Telomere length, DNA methylation, cognition, physical function | MixedLonger telomere length and better chair-stand performance vs placebo; most other aging markers unchanged. |
Mood, cognition and nervous system — 5 trials
| Year | Study | Participants | Design | Dose & duration | What was measured | Result |
|---|---|---|---|---|---|---|
| 2017 | Mizuno K et al. Medical Gas Research View study | 26 healthy adults | Randomized, double-blind, placebo-controlled crossover | 600 mL/day, 4 weeks | Mood (K6), anxiety, autonomic nerve function | MixedBetter mood and anxiety scores and improved autonomic balance vs placebo; no change in sleep quality or fatigue scores. |
| 2013 | Yoritaka A et al. Movement Disorders View study | 17 patients with Parkinson's disease on levodopa | Randomized, double-blind, placebo-controlled pilot | 1 L/day, 48 weeks | UPDRS motor score | PositiveImproved UPDRS score vs worsening in placebo group. Small pilot. |
| 2018 | Yoritaka A et al. Movement Disorders View study | 178 patients with Parkinson's disease | Randomized, double-blind, placebo-controlled multicenter | 1 L/day, 72 weeks | UPDRS total score | Null / no effectNo significant difference between hydrogen water and placebo. The larger follow-up did not confirm the 2013 pilot. |
| 2018 | Nishimaki K et al. Current Alzheimer Research View study | 73 adults with mild cognitive impairment | Randomized, double-blind, placebo-controlled | 300 mL/day, 1 year | ADAS-cog cognitive score | Null / no effectNo significant difference overall. In the APOE4-carrier subgroup, scores improved vs placebo; subgroup finding needs replication. |
| 2011 | Ito M et al. Medical Gas Research View study | 14, then 22 patients with mitochondrial or inflammatory myopathies | Open-label, then randomized double-blind crossover | 1 L/day open-label 12 weeks; 0.5 L/day crossover 8 weeks | Lactate/pyruvate ratio, MMP-3, function | MixedOpen-label phase improved lactate/pyruvate and MMP-3; the blinded crossover showed only a lactate reduction. Small samples. |
Vascular and other — 2 trials
| Year | Study | Participants | Design | Dose & duration | What was measured | Result |
|---|---|---|---|---|---|---|
| 2014 | Sakai T et al. Vascular Health and Risk Management View study | 34 healthy adults | Randomized, double-blind, placebo-controlled | Single 500 mL dose containing >3.5 mg dissolved H₂ | Flow-mediated dilation (endothelial function) | PositiveImproved flow-mediated dilation 30 minutes after drinking vs placebo water. Acute effect only. |
| 2012 | Ostojic SM Mayo Clinic Proceedings (letter) View study | 19 healthy men | Randomized, placebo-controlled | 2 L/day, 14 days | Urinary and blood pH | PositiveHigher urinary pH and a small rise in blood pH; no adverse effects reported. |
How to read the results
Positive means the primary or main reported outcome favoured hydrogen water over the comparison. Mixed means some measured outcomes moved and others did not, or the study had no placebo, so the result cannot be separated from expectation effects. Null means the authors reported no significant difference on the main outcome.
Three cautions apply to the whole field. First, most trials have fewer than 40 participants, so a single result rarely settles anything. Second, doses vary from a 500 mL glass to two litres a day and from a single drink to 72 weeks, so trials are hard to compare. Third, effects were generally larger in people who started with elevated markers (high cholesterol, pre-diabetes, inflammation) than in healthy young adults, where several trials found nothing. A 2024 systematic review in the International Journal of Molecular Sciences titled "Hydrogen Water: Extra Healthy or a Hoax?" reached a similar conclusion: promising signals, small studies, more and larger trials needed.
Questions researchers ask
How many human trials of drinking hydrogen water are there?
This library lists 26 completed human trials in which participants drank hydrogen-rich water, published between 2008 and 2021.
Reviews often quote larger figures (1,000 to 2,000-plus "studies"), but those counts include animal, cell and inhalation studies and narrative reviews. Drinking-water trials in people are a much smaller set.
What dose did the trials use?
Most trials used 0.5 to 2 litres per day of water containing roughly 0.5 to 1.6 mg/L of dissolved hydrogen; tablet-based trials delivered about 12 mg of hydrogen per day.
Dissolved hydrogen at 1 atmosphere saturates near 1.6 mg/L (1.6 ppm). Higher "ppm" figures quoted for tablets describe a temporary supersaturated state in a sealed container, which is explained in our guide to measuring hydrogen water.
Which trials found no effect?
The 2018 multicentre Parkinson's trial (178 patients, 72 weeks), the 2018 mild-cognitive-impairment trial (73 patients, 1 year) and the 2013 hepatitis B trial (60 patients) all reported no significant difference on their main outcome.
Several exercise trials also found no change in specific measures such as 48-hour soreness, lactate or performance even when other measures moved. We list those as mixed.
Were any adverse effects reported?
None of the listed trials reported serious adverse events attributed to hydrogen water, including the 72-week and 1-year studies.
Some participants in high-volume protocols (1.5–2 L/day) reported loose stools or increased urination related to the water volume. Long-term data beyond 18 months does not exist.
Last reviewed October 2026. Sources: the trials linked in each table above.
Related: The science of molecular hydrogen → · Do hydrogen tablets actually work? → · How to measure hydrogen water →