Well, a team of Japanese scientists traveled around the world testing these famous springs.
The one thing they all had in common? A higher than normal amount of dissolved H2.
Molecular Hydrogen is the most potent antioxidant in existence.
The hydrogen molecule is tiny, and not only goes inside your cells, it goes right inside your mitochondria, repairing and protecting them from oxidative damage.
Whatever that cell is there to do, it's now able to do it better and for a longer period of time.
So how does Magnesium tie into this?
Well the rock the water rushed past in those famous springs contained a high magnesium content. Water reacts with magnesium to produce Molecular Hydrogen.
But there's also some magnesium left over in the water once the reaction is done.