Scientifically, the maximum amount of hydrogen dissolvable in water is about 0.00016 g/L, or about 1.6 mg/L.

Many "hydrogen water" manufacturers claim that the hydrogen concentration in their hydrogen water is up to 1000 ppb (parts per billion). It means that there are 1000 molecules of hydrogen for every billion water molecules. In terms of mass, this is equivalent to 1 microgram (mg) of hydrogen per liter of water.

Suppose we drink 2 liters of hydrogen water daily, the maximum hydrogen intake would be about 2mg per day

Compared to a medical class hydrogen inhalation device that generates hydrogen gas at 3 L/min, 60 mins of hydrogen inhalation would be equivalent to 18L hydrogen.

Suppose only about 20% of hydrogen was successfully inhaled, that translates to 3.6L of hydrogen at standard temperature and pressure (STP), the density of hydrogen gas is about 0.08988 grams per liter (g/L).

3.6L *0.08988 g/L = 0.323568 g
 ~ 323 mg ~ 300 L of water

In other words, one hour of 3L/min hydrogen inhalation is equivalent to drinking 300 litres of hydrogen water.

Hydrogen Gas generated from Hydrogen Inhalation Device

Hydroxyl Radical will react with hydrogen molecules to form water

For cancer treatment rehabilitation, we recommend to inhale more than one hour of hydrogen gas, which is equivalent to drinking 300 L of hydrogen water

At such, drinking hydrogen water is, at best, a good preventive measure.

The therapeutic effect of drinking hydrogen water cannot be compared to hydrogen inhalation.