How Much Hydrogen Water Per Day? Doses Used in Human Studies

By Hydrogen Studies Editorial Team · Updated

Hydrogen Studies is funded by Echo Technologies LLC, which sells hydrogen water products. Echo doesn't decide which studies we cover or how we describe them — see our editorial policy.

Short answer: No one has established how much hydrogen water to drink per day; there is no known optimal or minimum dose. In the 16 human trials below, most people drank 0.5 to 2 liters a day at about 0.5 to 15 ppm, for anywhere from a single drink to 72 weeks. Positive and negative results appear at low and high doses alike, and only one small trial compared two amounts directly, so our confidence in any specific daily dose is low.

What doses did human trials actually use?

Below are 16 trials in which people drank hydrogen-rich water; 14 had a placebo or control group. Every figure comes from each paper's abstract or full text, and where we couldn't find a number, we say so. For more trials, browse our hydrogen water studies or the full study database.

Study Who took part n H₂ concentration (as reported) Amount per day Duration Approx. H₂/day* Main result
Kajiyama 2008 [1] Type 2 diabetes or impaired glucose tolerance 36 Not stated in abstract 900 mL 8 wk (crossover) — Improved: some lipid and oxidative-stress markers
Nakao 2010 [2] Signs of metabolic syndrome (no control group) 20 0.55–0.65 mM 1.5–2 L in 5 servings 8 wk ≈1.7–2.6 mg Improved: antioxidant and HDL markers; fasting glucose unchanged
Kang 2011 [3] Radiotherapy for liver tumors 49 0.55–0.65 mM 1.5–2 L in 10+ servings 6 wk ≈1.7–2.6 mg Improved: quality of life vs placebo; fatigue and sleep no different
Ito 2011 (randomized part) [4] Mitochondrial or inflammatory muscle disease 22 ~0.5 ppm 0.5 L in 2–5 servings 8 wk (crossover) ≈0.25 mg No clinical effect; lactate improved in one subgroup
Ishibashi 2012 [5] Rheumatoid arthritis (no control group) 20 4–5 ppm 530 mL within 1 hour 4 wk, twice ≈2.1–2.7 mg Improved: disease-activity score and an oxidative-stress marker
Yoritaka 2013 [6] Parkinson's disease on levodopa 17 Not stated in abstract 1 L 48 wk — Improved: symptom score (UPDRS) vs placebo
Sakai 2014 [7] Healthy volunteers 34 7 ppm One 500 mL drink Single dose ≈3.5 mg Improved: artery dilation vs placebo 30 min later
Yoritaka 2018 [8–10] Parkinson's disease 178 5 mM per protocol† 1 L (2 × 500 mL) 72 wk Not calculated† No significant difference vs placebo
Nishimaki 2018 [11] Mild cognitive impairment 73 >0.6 mM ~320 mL drunk (500 mL supplied) 1 yr ≈0.4 mg or more No overall difference; APOE4 carriers improved (subgroup)
Mizuno 2018 [12] Healthy adults 26 0.8–1.2 ppm 600 mL (2 × 300 mL) 4 wk (crossover) ≈0.5–0.7 mg Mixed: mood/anxiety and resting sympathetic activity improved; blood markers unchanged
Sim 2020 [13] Healthy adults 38 0.753 mg/L 1.5 L (3 × 500 mL) 4 wk ≈1.1 mg Mixed: main antioxidant markers same as plain water; fewer dying immune cells
LeBaron 2020 [14] Metabolic syndrome 60 Tablets; >5.5 mmol H₂/day 750 mL (3 × 250 mL) 24 wk ≈11 mg or more Improved: cholesterol, glucose, HbA1c, inflammation markers vs placebo
Zanini 2021 [15] Adults aged 70+ 40 15 ppm 0.5 L 6 mo ≈7.5 mg Mixed: telomere length and some brain and physical measures improved; most unchanged
Ogawa 2021 [16] Type 2 diabetes 43 analyzed Not in main text (electrolyzed water) 1.5–2 L 3 mo — No difference in insulin resistance (main outcome)
Wu 2024 [17] High uric acid 100 completed ≥4.66 mg/L 660 or 990 mL (2 or 3 × 330 mL) 8 wk ≈3.1 or 4.6 mg Mixed: uric acid fell from baseline only in the 3-can group
Gaboreau 2024 [18] Outpatients with COVID-19 675 Not in main text (tablets) 500 mL (2 × 250 mL) 21 days — No difference in clinical worsening vs placebo

*Approx. H₂/day = liters per day × mg per liter (1 ppm = 1 mg/L; 1 mM ≈ 2 mg/L). It assumes the reported concentration was still in the water when people drank it, which isn't guaranteed (see below). "—" means the concentration wasn't reported in the text we read.

†The published protocol says 5 mM (about 10 mg/L). We couldn't read the results letter to confirm what was delivered, so we didn't calculate a daily amount; the result is as described in a 2025 review [10].

What's the typical range, and is there an optimal dose?

Trials cluster around 0.5–1 liter a day for a few weeks, but they don't point to an optimal or minimum dose.

  • Volume: 11 of the 15 daily-drinking trials used 1 liter a day or less; four used 1.5–2 liters [2, 3, 13, 16].
  • Concentration: About 0.5 ppm [4] to 15 ppm [15]. Four trials didn't report it in the text we read.
  • Duration: A single drink [7] to 72 weeks [8, 9]. Ten of the 16 lasted 3–13 weeks.
  • Daily hydrogen: Where we could calculate it, roughly 0.25 to 11 mg, about a 40-fold spread.

A 72-week Parkinson's trial at 1 liter a day [8–10] and a diabetes trial at 1.5–2 liters a day [16] found no difference on their main outcomes, while a 24-week trial at an estimated 11 mg or more a day reported improvements [14]. These trials studied different people and outcomes, so they can't be lined up into a dose-response curve. A 2012 review noted that no dose-response effect had been seen [19], and the team behind the largest trial here wrote in 2024 that the effective dose "has yet to be determined" [18].

What does "ppm" mean, and how much hydrogen can water hold?

In hydrogen water, ppm means milligrams of hydrogen per liter. At room temperature and normal air pressure, water holds only about 1.6 ppm; higher levels are supersaturated and fall once exposed to air.

One ppm equals 1 mg/L [20]. Papers that report millimolar (mM) convert at about 2 mg/L per mM, so the 0.55–0.65 mM in two early trials [2, 3] is roughly 1.1–1.3 ppm. At about 20 °C and normal pressure, hydrogen dissolves to about 1.6 mg/L, or about 0.8 mM [17], which trial authors call "saturated" [5]. To go higher, hydrogen is dissolved under pressure: in one lab test, sealed pressure-resistant bottles reached about 4.5–6 atmospheres and held roughly 7–10 ppm [20]. The 4–7 ppm drinks in two trials were made this way [5, 7]; tablet trials generated hydrogen directly in the drink [14, 18]. Our ppm guide and what is hydrogen water? cover how it's made.

How long does hydrogen water last once it's opened?

Not long. Concentration drops measurably within an hour of opening, which is why most trials had people drink it within minutes to an hour.

  • In the arthritis trial, freshly made water measured 5.4 mg/L, and 4.2 mg/L one hour after the cap was opened [5].
  • In a lab study by scientists at a hydrogen-water company, sealed pressure-resistant bottles held about 7 ppm after 24 hours and more than 8 ppm after 7 days, but levels fell significantly within 1 hour of opening and again by 2 hours [20].
  • Trials told people to finish each serving within 5 minutes [12] or 10 minutes [17], or within 1 hour [5, 13] or 3 hours [9] of opening.

Containers matter too. In one comparison, aluminum and stainless-steel containers lost very little hydrogen over 12 hours, while several plastic containers lost more [21]. Many trials supplied water in aluminum pouches or cans [4, 11, 12, 17].

When did trials have people drink it?

Some trials split the daily amount into 2 to 10 or more servings; others used a single daily serving, such as 530 mL within an hour [5]. No trial we found compared the two head-to-head.

  • Spread out: five 300–400 mL servings before meals, after lunch and before bed [2]; 100–300 mL more than 10 times a day [3]; morning, noon and evening [17]; breakfast and dinner [12]; three tablet drinks a day [14].
  • Before exercise: 600 mL within 30 minutes before cycling lowered blood lactate and perceived effort at higher intensities in 12 men [23]. Two 290 mL doses before treadmill running didn't change performance in 14 trained runners [24].

Why spread it out? In 5 adults, breath hydrogen peaked 10–15 minutes after drinking and soon returned to baseline, with bigger drinks giving bigger peaks [22]. In 3 volunteers it peaked at 5 minutes and was near baseline by 60 minutes [5]. That short window is one rationale for multiple servings, but splitting hasn't been tested for any health outcome.

How to read the table if you want to match what studies used

If you want to match what studies used, the relevant numbers are the concentration at the time you drink and your daily volume.

Multiply them: liters per day × mg/L. For example, 1 liter at 1.2 ppm is about 1.2 mg, and 0.5 liter at 5 ppm is about 2.5 mg. Three caveats:

  • What counts is what's in the glass. Trials measured concentration with lab sensors [11, 13, 17]. A figure measured when the water was made doesn't account for time spent open.
  • Pick a trial that fits you: similar people, an outcome you care about, and ideally a placebo group. Trials without a control group [2, 5] are weaker evidence.
  • Matching a dose isn't matching a result. Several positive findings are small single trials that haven't been repeated, and the two largest trials found no benefit [8, 10, 18].

For the bigger picture, see is hydrogen water real or a scam?

Who should check with a clinician first?

Check first if you limit fluids, have reduced kidney function, or take glucose-lowering medication.

  • Fluid limits. Some trials used up to 2 liters of water a day [2, 3, 16]. If you've been told to limit fluids, that counts.
  • Magnesium tablets and sticks. These make hydrogen by reacting magnesium with water, leaving magnesium hydroxide behind (Mg + 2H₂O → Mg(OH)₂ + H₂) [2, 3]. The US National Library of Medicine notes that side effects from high magnesium intake are uncommon except in people with significantly reduced kidney function [25]. See is hydrogen water good for your kidneys?
  • Diabetes medication. In one trial, an insulin-treated patient had low blood sugar episodes that subsided when the insulin dose was lowered [4]. One case can't show cause, but tell your clinician.

More detail: hydrogen water side effects and safety.

What the evidence doesn't show

The evidence doesn't show a best dose, a minimum effective dose, or that more is better.

  • Only one head-to-head dose comparison. In the uric acid trial, levels fell significantly from baseline with three cans a day but not two. The share of people with a 10% or larger drop didn't differ significantly between groups, and investigators weren't blinded [17].
  • Doses are hard to compare. Concentrations varied about 30-fold and were usually measured when the water was made, not when it was drunk.
  • Small and short. 13 of the 16 trials analyzed fewer than 75 people, and most lasted 3–13 weeks. The two largest (178 and 675 people) found no benefit on their main outcomes [8–10, 18].
  • Extra water. In one trial, the plain-water group also improved on antioxidant and DNA-damage markers; participants were drinking about 300 mL more water than usual [13].
  • Industry ties. Several studies were co-authored by employees of hydrogen-water companies or used donated product [7, 11, 16, 20]. Our own funding is disclosed at the top of this page; see our methodology.

Frequently asked questions

How much hydrogen water should I drink a day?

There's no established amount. Most human trials used 1 liter a day or less, and a few used 1.5 to 2 liters, usually for 3 to 13 weeks. Results were mixed at every amount, so no daily dose has been shown to work better than another.

What ppm of hydrogen water is best?

No trial has identified a best concentration; studies used roughly 0.5 to 15 ppm. Water at room temperature and normal pressure holds only about 1.6 ppm, so higher levels are supersaturated, made under pressure or with tablets, and they fall once exposed to air.

How long does hydrogen water last after opening?

Hydrogen starts escaping once the container is opened. In one measurement, water dropped from 5.4 to 4.2 mg/L within an hour, and a lab test found further significant losses by 2 hours. Trials typically asked people to drink it within minutes to an hour.

When is the best time to drink hydrogen water?

No study has tested the best time. Trials used morning, noon and evening servings, servings before meals and at bedtime, or a drink shortly before exercise. Breath tests suggest hydrogen from one drink clears within about an hour, one reason some trials split the daily amount.

Is drinking more hydrogen water better?

That hasn't been shown. The only trial that compared two amounts found uric acid fell from baseline with three cans a day but not with two, yet the groups didn't differ significantly in how many people improved. Other trials show positive and negative results at both low and high doses.

Sources

  1. Kajiyama S, et al. Supplementation of hydrogen-rich water improves lipid and glucose metabolism in patients with type 2 diabetes or impaired glucose tolerance. Nutrition Research. 2008. PubMed · Our summary
  2. Nakao A, et al. Effectiveness of hydrogen rich water on antioxidant status of subjects with potential metabolic syndrome — an open label pilot study. Journal of Clinical Biochemistry and Nutrition. 2010. PubMed · Our summary
  3. Kang KM, et al. Effects of drinking hydrogen-rich water on the quality of life of patients treated with radiotherapy for liver tumors. Medical Gas Research. 2011. PubMed · Our summary
  4. Ito M, et al. Open-label trial and randomized, double-blind, placebo-controlled, crossover trial of hydrogen-enriched water for mitochondrial and inflammatory myopathies. Medical Gas Research. 2011. PubMed · Our summary
  5. Ishibashi T, et al. Consumption of water containing a high concentration of molecular hydrogen reduces oxidative stress and disease activity in patients with rheumatoid arthritis: an open-label pilot study. Medical Gas Research. 2012. PubMed · Our summary
  6. Yoritaka A, et al. Pilot study of H₂ therapy in Parkinson's disease: a randomized double-blind placebo-controlled trial. Movement Disorders. 2013. PubMed · Our summary
  7. Sakai T, et al. Consumption of water containing over 3.5 mg of dissolved hydrogen could improve vascular endothelial function. Vascular Health and Risk Management. 2014. PubMed · Our summary
  8. Yoritaka A, et al. Randomized, double-blind, multicenter trial of hydrogen water for Parkinson's disease. Movement Disorders. 2018. PubMed · Our summary
  9. Yoritaka A, et al. A randomized double-blind multi-center trial of hydrogen water for Parkinson's disease: protocol and baseline characteristics. BMC Neurology. 2016. PubMed · Our summary
  10. Wang F, et al. Role and mechanism of molecular hydrogen in the treatment of Parkinson's diseases. Frontiers in Neuroscience. 2025. PubMed · Our summary
  11. Nishimaki K, et al. Effects of molecular hydrogen assessed by an animal model and a randomized clinical study on mild cognitive impairment. Current Alzheimer Research. 2018. PubMed · Our summary
  12. Mizuno K, et al. Hydrogen-rich water for improvements of mood, anxiety, and autonomic nerve function in daily life. Medical Gas Research. 2018. PubMed · Our summary
  13. Sim M, et al. Hydrogen-rich water reduces inflammatory responses and prevents apoptosis of peripheral blood cells in healthy adults: a randomized, double-blind, controlled trial. Scientific Reports. 2020. PubMed · Our summary
  14. LeBaron TW, et al. The effects of 24-week, high-concentration hydrogen-rich water on body composition, blood lipid profiles and inflammation biomarkers in men and women with metabolic syndrome: a randomized controlled trial. Diabetes, Metabolic Syndrome and Obesity. 2020. PubMed · Our summary
  15. Zanini D, et al. The effects of 6-month hydrogen-rich water intake on molecular and phenotypic biomarkers of aging in older adults aged 70 years and over: a randomized controlled pilot trial. Experimental Gerontology. 2021. PubMed · Our summary
  16. Ogawa S, et al. Electrolyzed hydrogen-rich water for oxidative stress suppression and improvement of insulin resistance: a multicenter prospective double-blind randomized control trial. Diabetology International. 2021. PubMed · Our summary
  17. Wu F, et al. Effects of hydrogen-rich water on blood uric acid in patients with hyperuricemia: a randomized placebo-controlled trial. Heliyon. 2024. PubMed · Our summary
  18. Gaboreau Y, et al. Molecular hydrogen for outpatients with COVID-19 (Hydro-COVID): a phase 3 randomised, triple-blinded, pragmatic, placebo-controlled, multicentre trial. Journal of Clinical Medicine. 2024. PubMed · Our summary
  19. Ohno K, et al. Molecular hydrogen as an emerging therapeutic medical gas for neurodegenerative and other diseases. Oxidative Medicine and Cellular Longevity. 2012. PubMed · Our summary
  20. Kurokawa R, et al. Convenient methods for ingestion of molecular hydrogen: drinking, injection, and inhalation. Medical Gas Research. 2015. PubMed · Our summary
  21. Tanaka Y, et al. Dependencies of hydrogen-water on mineral-based hardness, temperatures and the container materials, and effects of the oral washing and drinking. Medical Gas Research. 2020. PubMed · Our summary
  22. Shimouchi A, et al. Breath hydrogen produced by ingestion of commercial hydrogen water and milk. Biomarker Insights. 2009. PubMed · Our summary
  23. Botek M, et al. Hydrogen rich water improved ventilatory, perceptual and lactate responses to exercise. International Journal of Sports Medicine. 2019. PubMed · Our summary
  24. Ooi CH, et al. Acute ingestion of hydrogen-rich water does not improve incremental treadmill running performance in endurance-trained athletes. Applied Physiology, Nutrition, and Metabolism. 2019. PubMed · Our summary
  25. MedlinePlus (US National Library of Medicine). Magnesium in diet. https://medlineplus.gov/ency/article/002423.htm

How we wrote this: drafted with AI assistance from the sources above and checked against each source by the Hydrogen Studies editorial team. This is general information, not medical advice — talk to your clinician before changing any treatment.