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.
How much hydrogen does inhalation actually deliver?
The honest answer starts with a complication: the research doesn't report dose in one consistent way. Some studies give a flow rate in millilitres per minute, some give a concentration, some describe a hydrogen-oxygen mixture. Comparing the raw numbers directly would mislead — a high carrier-gas flow at a low concentration can deliver less hydrogen than a small flow of pure hydrogen. What matters is the hydrogen actually delivered.
On that basis, a picture emerges. The human studies into everyday wellness and safety have tended to deliver modest amounts. Grepl and colleagues (2025) used an inhaled-hydrogen flow of 300 ml/min (99.8% pure) in their resting-metabolism study. Cole and colleagues (2021), in the prolonged-exposure safety study, used 2.4% hydrogen in medical air at high flow — around 360 ml/min of hydrogen. In an animal model, Sano and colleagues (2020) found that even 250 ml/min produced blood concentrations the wider literature considers physiologically active.
Clinical hydrogen-oxygen protocols run considerably higher. The medical nebulisers used in respiratory trials deliver a 66% hydrogen / 33% oxygen mixture at three litres per minute — around 2,000 ml/min of hydrogen.
Our machines produce that same 66.6% hydrogen / 33.3% oxygen mixture. The Hydro Nova, at 1,500 ml/min, delivers around 1,000 ml/min of hydrogen — comfortably above the amounts used in the published wellness research. The Hydro Medic, at 3,000 ml/min, delivers around 2,000 ml/min — the level used in the clinical respiratory protocols. This is what we mean when we say the Nova is built around the dose serious research has used, rather than the minimum that has been tested.
A note in the spirit of honesty: the hydrogen-delivered figures for the concentration- and mixture-based studies, and for our own machines, are calculated from concentration and flow — not numbers the studies state directly. And more hydrogen delivered is not the same as proportionally more benefit; the dose-response relationship in people is still being worked out. What the comparison shows is that inhalation at our machines' output sits within, and often above, the range the research has actually studied.
Is more hydrogen well tolerated?
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.
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.
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.
