Hydrogen water: what it is, what the research says, and whether it’s a scam

What is hydrogen water?

Hydrogen water (also called hydrogen-rich water or H₂ water) is normal drinking water with molecular hydrogen gas, H₂, dissolved in it. Nothing else changes: it looks, smells and tastes like water.

The amount of hydrogen is measured in milligrams per litre (mg/L), which is the same as parts per million (ppm). At normal air pressure and room temperature, water can hold about 1.6 mg/L of hydrogen.⁴ Devices that build pressure, like a sealed bottle, can push the level higher for a short time.

Isn’t there already hydrogen in water?

Yes, but it’s locked in. Water is H₂O: two hydrogen atoms bound to one oxygen atom. That hydrogen is part of the water molecule and isn’t available as a gas. Hydrogen water contains free H₂ molecules floating between the water molecules, the same way sparkling water contains free CO₂. A hydrogen bottle makes them by electrolysis: a small current splits some of the water into hydrogen and oxygen.

Why the hydrogen molecule is special

H₂ is the smallest molecule in the universe. It has no charge and dissolves in both water and fat, so it passes through cell membranes easily and spreads through the body within minutes. It’s also very unreactive at body temperature, which is part of why it’s considered safe, and part of why it took researchers so long to work out what it actually does.

How does hydrogen water work?

Honest answer: the full mechanism is still being worked out. There have been two main theories.

Theory 1: a selective antioxidant

Your cells produce reactive molecules called free radicals all the time. Most are useful signals, but a few, like the hydroxyl radical, are harmful in excess. This imbalance is called oxidative stress. In 2007, a Japanese team led by Ikuroh Ohsawa published a study in Nature Medicine showing that hydrogen reacted with the most aggressive radicals, the hydroxyl radical and peroxynitrite, but not with the milder ones the body uses as signals.¹ That paper started the modern research field.

The problem: at the small amounts you get from drinking, hydrogen reacts too slowly to mop up many radicals directly, and it leaves the body within an hour or so while its effects appear to last longer. So the antioxidant idea alone doesn’t add up.

Theory 2: a signal (the leading thesis today)

Most researchers now see hydrogen as a signalling molecule. It gives the cell’s power plants, the mitochondria, a small, harmless nudge. The cell answers by switching on its own protection and repair, a bit like the body adapts to exercise. This is called mitohormesis.

In 2025 researchers identified what may be the first direct target: a protein in the mitochondria called the Rieske protein.² Other groups are testing the finding, and not everyone agrees yet.³

What does the research say?

Molecular hydrogen has gone from a curiosity to one of the most studied molecules in wellness research. A 2023 review counted more than 2,000 scientific publications, along with 81 registered clinical trials and 64 published human studies.⁵ The Molecular Hydrogen Institute, which tracks the field, now lists more than 3,000 studies.¹⁴ Most of the work is in cells and animals; human studies are growing but still fewer.

The same review concluded that very few side effects have been reported and that all the trials considered hydrogen safe for humans.⁵ On what it actually does in people, the picture is still mixed.

Areas that have been studied include recovery after exercise, markers of oxidative stress and inflammation, metabolism, and ageing. Many studies are small, short, or done in animals, and results vary between studies. That’s why no one can honestly promise you a specific effect.

Is hydrogen water a scam?

The science isn’t a scam. Hydrogen is a real, measurable molecule with a large body of peer-reviewed research behind it. But plenty of products sold as hydrogen water don’t deliver. That’s where the “scam” reputation comes from, and it’s often deserved.

Five signs of a bad hydrogen water product

1. A big number nobody measured. “5,000 ppb” or “8 ppm” on the box, with no independent lab report behind it.
2. ORP instead of hydrogen. A negative ORP reading is not a hydrogen measurement.⁶ Real levels are measured with gas chromatography or a hydrogen-specific titration reagent.
3. No membrane, or a cheap one. Without a proper proton-exchange membrane, electrolysis can put ozone, chlorine or metal traces into the water.
4. Health promises. “Cures”, “prevents cancer”, “detox”. There are no approved health claims for hydrogen water in the EU.
5. Pre-filled water that sat on a shelf. Hydrogen escapes through most packaging. Unless it’s in sealed aluminium and tested, there may be little left.

Is hydrogen water safe? Side effects

Hydrogen water has a good safety record. Your gut bacteria already make hydrogen every day, and the extra amount from a glass of hydrogen water is small. What your body doesn’t use, you breathe out.

• Approved in the EU as food additive E 949. Hydrogen is authorised in all food categories, and the European Food Safety Authority (EFSA) re-evaluated it in 2025 and found that it does not raise a safety concern.⁸
• Accepted in the US. In 2014 the FDA responded with “no questions” to a notice that hydrogen gas in drinking water is generally recognised as safe (GRAS notice 520).⁹
• Well tolerated in trials. Across human studies, very few adverse reactions have been reported.⁵

A few practical notes: drink it as you would normal water, not litres at a time. If you’re pregnant, have a medical condition or take medication, talk to your doctor before adding anything new to your routine, as you would with any supplement. Hydrogen water is not a substitute for medical treatment.

What the EU and authorities say

In the EU, a food or drink may only be marketed with health claims that have been scientifically assessed and approved. There are no approved health claims for hydrogen or hydrogen water; the approved water claims apply to plain water in general.¹⁰

The Swedish Food Agency (Livsmedelsverket) has no specific guidance on hydrogen water. It lists hydrogen as an approved additive (E 949, used as a packaging gas) and points out that only EU-approved health claims may be used.⁸¹¹

Japan leads much of the research. Hydrogen gas inhalation has, for example, been studied in Japanese hospitals in a multicentre trial with patients after cardiac arrest.¹²

This is why we write about research, not promises. You won’t find health claims about our products on this site.

How to make hydrogen water

There are four common ways. The difference is how much hydrogen you actually get, how fresh it is, and what it costs over time.

How much hydrogen water, and when?

There is no official recommendation. Human drinking studies have typically used about 0.5 to 1.5 litres a day, at around 1–2 mg/L, some at higher levels.⁵

Timing matters less than habit. What matters most is freshness: hydrogen starts escaping as soon as the water meets open air. In an open container, roughly half can be lost within about two hours, faster when it’s warm or stirred.⁶ Make it fresh and drink it within a few minutes. Don’t leave it in an open glass or keep refilling the same water.

For the Nord Hydrogen Bottle, the routine is simple: fill to the thread, run a 10-minute cycle, drink it all. Details are in our guide to using the bottle.

How to choose a hydrogen water bottle

Most bottles look alike, and most make the same claims. These five questions separate them:

• Is the hydrogen level measured by an independent lab? Ask for the report, and check that it used gas chromatography or a hydrogen-specific method, not ORP.
• Does it have a proton-exchange membrane (PEM/SPE)? This separates hydrogen from oxygen and by-products.
• Was the water tested for ozone and chlorine? Cheap cells can make both.
• Is it independently certified? The International Hydrogen Standards Association (IHSA) tests and certifies hydrogen products.
• Who handles repairs? A bottle you use daily needs a warranty and real support.

We compared the market on exactly these points in best hydrogen water bottle, and publish every test of our own bottle in the Proof Center.

A short history of hydrogen water

• 1975: The journal Science publishes one of the first studies of hydrogen’s biological effects, in mice breathing hydrogen under high pressure.¹³
• 2007: Ohsawa and colleagues publish their Nature Medicine paper, and research takes off.¹
• 2010s: Hundreds of studies follow, from cell and animal work to human trials. Japan leads the field.
• 2025: Researchers point to the Rieske protein in mitochondria as a direct target.²

You may have heard that hydrogen explains the famous spring water of Lourdes in France, or other “healing waters”. It’s a popular story, but it hasn’t been proven, so we don’t rely on it.

Questions and answers about hydrogen water

Measured, not claimed.

The Nord Hydrogen Bottle reached 5.14 mg/L in an independent gas chromatography test. Every report is public.

See the bottle · €214 See the lab reports

Sources

1. Ohsawa I, Ishikawa M, Takahashi K, et al. Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals. Nature Medicine 13 (2007): 688–694. PubMed
2. Negishi S, Ito M, Hasegawa T, et al. The Rieske iron-sulfur protein is a primary target of molecular hydrogen. Redox Biology 88 (2025). PMC12719095
3. Revisiting molecular hydrogen signaling in mitochondria: is the Rieske protein the entry point or a downstream sentinel? PMC12808497
4. LeBaron TW, Sharpe R, Ohno K. Electrolyzed-reduced water: review I. Molecular hydrogen is the exclusive agent responsible for the therapeutic effects. Int J Mol Sci 23 (2022): 14750. PubMed
5. Johnsen HM, Hiorth M, Klaveness J. Molecular hydrogen therapy: a review on clinical studies and outcomes. Molecules 28 (2023): 7785. PMC10707987
6. LeBaron TW, Sharpe R. ORP should not be used to estimate or compare concentrations of aqueous H₂. Frontiers in Food Science and Technology 2 (2022). Frontiers
7. Nakao A, Toyoda Y, Sharma P, Evans M, Guthrie N. Effectiveness of hydrogen rich water on antioxidant status of subjects with potential metabolic syndrome. J Clin Biochem Nutr 46 (2010): 140–149. PMC2831093
8. Regulation (EC) No 1333/2008 on food additives, Annex II (E 949). EUR-Lex. EFSA FAF Panel, re-evaluation of hydrogen (E 949), EFSA Journal 23 (2025): e9595. EFSA. Livsmedelsverket, E 949 Väte. livsmedelsverket.se
9. U.S. FDA, GRAS Notice No. 520: hydrogen gas (2014). FDA
10. Commission Regulation (EU) No 432/2012, list of permitted health claims. EU Register of health claims
11. Livsmedelsverket, nutrition and health claims on food. livsmedelsverket.se
12. Tamura T, Suzuki M, Homma K, Sano M; HYBRID II Study Group. Efficacy of inhaled hydrogen on neurological outcome following out-of-hospital cardiac arrest (HYBRID II). eClinicalMedicine 58 (2023): 101907. PubMed
13. Dole M, Wilson FR, Fife WP. Hyperbaric hydrogen therapy: a possible treatment for cancer. Science 190 (1975): 152–154. PubMed
14. Molecular Hydrogen Institute, overview of the research on molecular hydrogen. molecularhydrogeninstitute.org