Molecular Hydrogen (two atoms of hydrogen combined into one molecule) is a powerful antioxidant that selectively targets the most toxic of free radicals, the hydroxyl group. The ability to selectively target free radicals is important as it means that it will not interfere with adjunctive therapies doctors may be pursuing. A healthy body creates free radicals as a result of normal activity & metabolism. These free radicals, known as ROS (reactive oxygen species) or RNS (reactive nitrogen species) are kept in check by the healthy body, maintaining normal mitochondrial function. Health challenges, including chemical exposure or physical stress, provide additional obstacles to maintaining this balance. In contrast to many antioxidants, molecular hydrogen is able to penetrate the blood-brain barrier.