Molecular Hydrogen – Benefits for Health and Performance Molecular hydrogen (H2 or MH) is the most lightweight gas and the lightest and most abundant chemical element. It can act as an antioxidant by suppressing free radical chain reactions, thereby reducing the production of reactive oxygen species (ROS). The therapeutic application of H2 as a free radical catalyzer was first documented in the 1970s. It was hypothesized that the underlying mechanism was through hydroxyl radicals scavenging by exothermic reaction (a chemical reaction in which less energy is needed to break bonds in the reactants than is released when new bonds form in the products) of H2 + ·OH = H2O...