Hydrogen enters the human body through the following ways: breathing, drinking hydrogen-rich water, injecting hydrogen-rich physiological saline, hydrogen bath, etc. Because hydrogen is the smallest molecule in the universe, no matter which way, hydrogen can give full play to its own characteristics and travel freely in the body to reach all parts of the body. Even the cell membrane will not stop it from spreading in the body. Therefore, through diffusion, hydrogen can be quickly absorbed by the human body.