Most consumer hydrogen devices advertise output in millilitres per minute. The number on the box has become the spec everyone fixates on — bigger sounds better, smaller sounds suspect. The reality is more interesting and a great deal more useful.
The hydrogen molecule is so small it is, in practical terms, almost trivial to get into the bloodstream. What's not trivial is delivering it at a dose meaningful enough to do anything, sustained long enough to matter, and then tracking which of those variables the underlying research actually measured.
If you've spent any time comparing inhalation devices, you'll have seen the gap between machines marketed at 150 ml/min and machines that quietly run several thousand. The implication, usually unstated, is that more is better. The literature tells a more nuanced story.
The dose equation isn't one number
Hydrogen dose isn't flow rate. It's flow rate × time × absorption × concentration in the breathing air. A 600 ml/min device used for sixty minutes delivers a different dose to a 1,500 ml/min device used for fifteen — and a meaningfully different dose again from a 600 ml/min device used for two hours.
The cleanest way to think about it: the body absorbs hydrogen at the alveolar boundary at roughly 20–40% efficiency depending on breathing rate, partial pressure, and individual physiology. The rest is exhaled. So when a study reports “60 minutes of inhalation at 300 ml/min,” what it's really telling you is that the participants had access to roughly 18 litres of hydrogen over an hour, of which somewhere between 3.6 and 7.2 litres reached the bloodstream.
That's the actual number worth caring about. Not what the box says.
What the human studies actually used
Here's where the picture clarifies. When you stop reading device marketing and start reading the trials themselves, a clear pattern emerges.
The metabolic and exercise research — the work most relevant to general wellness use — has clustered around 300–600 ml/min. Korovljev and Ostojic in 2024 ran a randomised crossover study on resting metabolism at 300 ml/min via nasal cannula, sixty minutes per session. Javorac and Ostojic the same year tested running performance using 4% gaseous hydrogen, twenty minutes per day for seven days. The Palacký University 2025 trial on exercise recovery used 600 ml/min.
The clinical and respiratory studies — work on cardiac arrest, COVID-19 recovery, and intensive care contexts — have run higher. 2,000 ml/min appeared in a major Type 2 diabetes trial. 3 L/min figures in cancer hospital protocols and severe respiratory disease trials.
Two distinct dose ranges, two distinct research literatures. The wellness end starts around 250 ml/min. The serious therapeutic end starts around 2,000.
Where the Hydro Nova sits
The Hydro Nova delivers 1,500 ml/min. That places it deliberately between the two ranges — above the typical wellness study, below the high-flow clinical trials.
This is a design choice, not an accident, and it's worth being honest about why.
The early wellness research used conservative doses. That made sense: the studies were investigating whether hydrogen did anything at all, and conservative dosing is how careful research begins. As the field has matured, doses have trended upward. The 600 ml/min Palacký trial is meaningfully higher than the 300 ml/min Korovljev study, which is meaningfully higher than the 45 ml/min Javorac protocol that diluted hydrogen into ambient air.
What the trajectory suggests — and what the high-flow clinical work demonstrates — is that hydrogen has a remarkably wide tolerance window. Cole and colleagues at Boston Children's Hospital put eight healthy adults on 2.4% hydrogen via high-flow nasal cannula at 15 L/min for 24, 48 and 72 hours continuously. No clinically significant adverse events. The 1,500 ml/min the Nova delivers across a 60-minute session is, by any measure, well within the tolerance the safety literature has demonstrated.
So the positioning is straightforward: at the dose serious research uses, not the minimum that has been tested. The Hydro Gen at 900 ml/min sits at the upper end of where wellness research has run. The Medic at 3,000 ml/min sits where intensive clinical protocols have run. The Nova is the everyday machine designed for daily use at a dose the literature has already explored at the higher end of the wellness range.
What more flow does not mean
It's tempting to read this and conclude that bigger is always better. The honest answer is that we don't yet know exactly where the dose-response curve plateaus, or whether there are diminishing returns past a certain threshold.
What we do know is that flow rate without time is meaningless, and time without flow rate is meaningless. A 3,000 ml/min device used for five minutes delivers less hydrogen than a 1,500 ml/min device used for an hour. A 1,500 ml/min device used for two hours delivers a great deal more than either. The reason most of our protocols cluster around 60-minute sessions is that this is what the most well-designed human research has used.
A higher-flow device gives you headroom — the ability to deliver the same dose in less time, or to deliver more dose in the same time, or to run longer sessions for those who want them. It doesn't, on its own, guarantee better outcomes. The variable that genuinely seems to matter is total hydrogen delivered, sustained over a period of time, into a breathing pattern the body can absorb.
The practical implication
If you're comparing hydrogen inhalation devices, the questions worth asking aren't only about flow rate. They're about flow rate combined with what the device sustains over a typical session, what proportion of the gas is pure H₂ versus diluted with ambient air, and whether the unit can run reliably for the duration the research actually used.
A device specced at 1,500 ml/min that runs cleanly for ninety minutes is delivering a dose meaningfully consistent with where the modern research is heading. A device specced at 300 ml/min that maxes out at twenty minutes is delivering somewhere around a fifth of that — which is fine if your goal is to match the early wellness studies, but is not the same intervention.
The number on the box is one variable. What matters is what's actually reaching your bloodstream, for how long, every day.
