Research suggests that molecular hydrogen has antioxidant, anti-inflammatory, and cell-protective properties. These effects may benefit various conditions, particularly those associated with high levels of oxidative stress, but current research is too limited to draw any meaningful conclusions.
One of the most long-standing, albeit niche, uses of molecular hydrogen is for deep-sea diving. Adding hydrogen gas to the breathing mixture as a substitute for nitrogen is one method for reducing the side effects of nitrogen gas in high-pressure environments. This isn’t through any drug-like effects of hydrogen, though; it’s simply because it’s replacing nitrogen gas so that less nitrogen can dissolve into the blood during a dive.[1][2]
Preliminary research also points to potential benefits in metabolic syndrome, nonalcoholic fatty liver disease, recovery following a heart attack or cardiac arrest, rheumatoid arthritis, cancer, exercise capacity, and some respiratory conditions.[3][4][5]