パーキンソン病患者における水素ガス吸入と尿中8-OHdG上昇：ランダム化二重盲検クロスオーバー試験
A randomized, double-blind, placebo-controlled crossover trial with an 8-week washout period enrolled 20 Parkinson's disease (PD) patients who inhaled approximately 1.2–1.4% hydrogen gas for 10 minutes twice daily over 4 weeks. Olfactory function, non-motor symptoms, activities of daily living, and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) were assessed. No statistically significant changes in clinical PD parameters were detected; however, urinary 8-OHdG concentrations rose by approximately 16%. This magnitude of increase is substantially smaller than the over 300% elevation seen in diabetes and is more comparable to levels observed following intense physical exercise. The authors propose that hydrogen-induced oxidative stress markers may reflect hormetic cellular adaptation, potentially involving Nrf2 and NF-κB pathway activation and heat shock responses, suggesting that beneficial effects of hydrogen could be mediated partly through such mechanisms.
Hydrogen inhalation may activate the Nrf2 and NF-κB signaling pathways along with heat shock responses, inducing cytoprotective cellular adaptations through a hormetic mechanism, as reflected by a modest elevation in urinary 8-OHdG.
For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.
See also:
https://h2-papers.org/en/papers/30713666