A rat model was used to induce brain damage by oxidative stress. A cerebral ischemia was produced followed by reperfusion, which resulted in a great quantity of reactive oxygen. Inhaling 1-4% H2 reduced brain damage considerably due to the reduction of the effects of oxidative stress caused by the hydroxyl radical (•OH). The research found that dissolved in arterial blood H2 increased after inhalation in proportion to the amount inhaled. It shown as well that the amount of venous blood dissolved H2 was lower than in the arterial blood, suggesting that H2 had been incorporated into the body.
These findings raised interest and awareness worldwide. Once published many scientists have investigated the therapeutic value of hydrogen in several disease models, inhaled as well as dissolved in water. Evidence of the protective effect of hydrogen against oxydative stress has been accumulated.