Hydrogen: From Stars to Fuel to Medicine

Hydrogen gas has garnered significant attention in recent years due to its remarkable antioxidant and anti-inflammatory properties. However, the extensive research on hydrogen’s applications in the energy sector often overshadows its potential as a medically and biologically active gas. Surprisingly, investigations into the biomedical aspects of H2 trace back to as early as 1793. Hydrogen exhibits exceptional pharmacokinetics, swiftly traversing cellular biomembranes, including the blood–brain and testes barriers, to access subcellular organelles. Following ingestion, hydrogen follows the path of least resistance through the circulatory system and is primarily eliminated through exhalation. Despite the intricate molecular mechanisms and precise targets remaining elusive, the antioxidant effects of hydrogen involve the upregulation of endogenous antioxidants via the activation of the Nrf2/keap1 pathway. Recent research highlights the potential role of Fe-porphyrin as a redox-related biosensor, facilitating hydrogen’s reactions with hydroxyl radicals and triggering additional signal transduction processes. Moreover, this review delves into the physicochemical properties of hydrogen, particularly emphasizing its molar solubility, considerations regarding the term saturation, and other unique characteristics of H2 are discussed. The expanding knowledge and research surrounding the history of H2 underscore its transformative potential in biomedical applications and pave the way for future advancements in harnessing its therapeutic properties.