There is a randomized controlled trial of hydrogen in acute stroke patients, and it reported positive results[1]. It is also one of the most easily misread studies in the entire hydrogen literature, because what it tested is not something anyone can do at home.
The intervention was 3 percent hydrogen gas, inhaled in hospital, starting within 24 hours of a stroke. It was not hydrogen water, not a tablet, and not a bottle. Before anything else on this page, that distinction needs to be clear, because the gap between “hydrogen helped stroke patients in a trial” and “hydrogen water helps your brain” is the entire subject of this article.
Why stroke, and why gas
An ischaemic stroke is a blockage that starves part of the brain of blood. Much of the lasting damage happens in the hours afterwards, when blood flow returns and the reperfused tissue generates a burst of reactive oxygen species. That injury window is the target.
Molecular hydrogen is of interest here because of its specific chemistry. It reacts with hydroxyl radical, one of the most destructive reactive species, without neutralising the reactive molecules the body uses for normal signalling[2]. It is also small, uncharged and lipid-soluble enough to cross membranes without a transporter, which in principle means it can reach brain tissue rather than stopping at the bloodstream.
Inhalation of 1 to 4 percent hydrogen gas was effective for improving cerebral infarction across multiple animal experiments, which is what motivated a human trial[1]. Brain stem infarction was also one of only six human diseases that had been studied with hydrogen at all as of a 2012 review, alongside type 2 diabetes, metabolic syndrome, hemodialysis, inflammatory and mitochondrial myopathies, and radiation-induced adverse effects[3]. Stroke was an early priority, not an afterthought.
What the trial actually did
The study was a randomized controlled clinical study assessing the safety and effectiveness of hydrogen treatment in patients with acute-stage cerebral infarction[1].
Fifty patients were enrolled, 25 in the hydrogen group and 25 in the control group. Severity was restricted to mild-to-moderate, defined as a National Institutes of Health Stroke Scale score of 2 to 6. The therapeutic time window was 6 to 24 hours from the stroke.
The hydrogen group inhaled 3 percent hydrogen gas for one hour, twice a day. The control group received conventional intravenous medications. Both ran for the initial 7 days[1].
Assessment continued over a 2-week study period and included daily vital signs, NIHSS scores, physical therapy indices, weekly blood chemistry, and brain magnetic resonance imaging scans.
The results
The hydrogen group showed no significant adverse effects, with improvements in oxygen saturation[1].
Significant effects were found on three measures. The relative signal intensity on MRI, which indicates the severity of the infarction site. The NIHSS score, which quantifies stroke severity clinically. And physical therapy evaluation, as judged by the Barthel Index, which measures independence in everyday activities such as feeding, dressing and mobility[1].
The authors concluded that hydrogen treatment was safe and effective in patients with acute cerebral infarction, and suggested potential for wider application[1].
One deliberate omission on this page: the published abstract states which measures reached significance but does not report the effect sizes or p-values for them. So none are quoted here. “Significant improvement in NIHSS” is what the source supports, and how large that improvement was is not something this page can tell you.
The three things that limit this trial
First, and most importantly, the control group is a conventional-treatment group, not a placebo group. Patients knew whether they were being given a gas to inhale for an hour twice a day. NIHSS scoring and Barthel Index scoring both involve human assessment, and stroke rehabilitation outcomes are sensitive to how much attention and structured contact a patient receives. An intervention that puts a clinician at the bedside for two hours a day is not neutral even if the gas does nothing. The MRI signal-intensity finding is the most resistant to this problem, because a scanner does not know which arm a patient is in.
Second, the sample is 50 patients at what appears to be a single institution, and the follow-up is 2 weeks. Stroke recovery continues for months. A 2-week outcome tells you about early trajectory, not about how independent someone is at 90 days, which is the endpoint stroke trials normally care most about.
Third, the eligibility criteria were narrow. NIHSS 2 to 6 is mild-to-moderate stroke. The trial says nothing about severe stroke, about haemorrhagic stroke, which is a completely different mechanism, or about patients presenting outside the 6 to 24 hour window.
Why this does not transfer to hydrogen water
This is the section that matters most, and it is the reason this trial gets misquoted.
The dose is not comparable. Breathing 3 percent hydrogen gas for one hour delivers a continuous supply across the entire surface area of the lungs. A glass of hydrogen water delivers a small fixed quantity of dissolved gas into the stomach, much of which leaves through the breath within minutes. These are different orders of magnitude, not different flavours of the same thing.
The timing is not reproducible. The trial started treatment 6 to 24 hours after a stroke, during the reperfusion injury window. That window is a specific, brief, biologically defined period. Drinking hydrogen water regularly as a healthy person is not an intervention in that window, because there is no injury to intervene in.
The setting is not reproducible either. This was inpatient care with monitoring, imaging, blood chemistry and conventional stroke treatment running alongside. The hydrogen was tested as an addition to standard care, never as a replacement for it.
Nothing in this trial supports drinking hydrogen water to prevent a stroke. Prevention was not studied. The trial enrolled people who had already had one.
What to do if you are actually worried about stroke
Stroke is a medical emergency and the single most useful thing on this page is not about hydrogen at all. If someone has sudden face drooping, arm weakness or speech difficulty, the response is emergency services immediately, because the treatments that work best are the ones given fastest.
For risk reduction, the interventions with the strongest evidence are the unglamorous ones: blood pressure control, atrial fibrillation management, not smoking, and treating diabetes and cholesterol. Anyone concerned about their stroke risk gets far more from a conversation with a doctor about those than from any supplement.
The bottom line
A randomized controlled study in 50 patients with mild-to-moderate acute cerebral infarction found that inhaling 3 percent hydrogen gas for one hour twice daily over 7 days, started 6 to 24 hours after the stroke, produced no significant adverse effects, improved oxygen saturation, and had significant effects on MRI signal intensity at the infarction site, NIHSS score and Barthel Index[1].
It is a small, short, unblinded trial of a hospital-administered medical gas given as an addition to standard stroke care. It is a legitimate reason for researchers to keep studying hydrogen in acute stroke. It is not a reason to buy anything, and it says nothing about drinking hydrogen water.
References
- Hydrogen Gas Inhalation Treatment in Acute Cerebral Infarction: A Randomized Controlled Clinical Study on Safety and Neuroprotection. Journal of Stroke and Cerebrovascular Diseases, 2017
- Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals. Nature Medicine, 2007
- Molecular hydrogen as an emerging therapeutic medical gas for neurodegenerative and other diseases. Oxidative Medicine and Cellular Longevity, 2012
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.
