Estimation of Molecular Hydrogen Consumption in the Human Whole Body After the Ingestion of Hydrogen-Rich Water

Abstract

Recent studies have revealed that inhaled or ingested hydrogen gas (H₂) inactivates reactive oxygen species such as hydroxyl radicals in various kinds of diseases and disorders in animal models and that H₂ reduces oxidative stress-induced damage in brain, heart, and other peripheral tissues. These reports suggested that exogenous H₂ is partially trapped by oxygen radicals. This study was conducted to evaluate H₂ consumption after the ingestion of H₂-rich water. Seven adult subjects ingested H₂-rich water. The H₂ content of their expired breath was measured by gas chromatography with a semiconductor. The ingestion of H₂-rich water rapidly increased breath H₂ content to its maximal level of approximately 36 ppm at 10 min after ingestion and thereafter decreased it to the baseline level within 60 min. Taken together with simultaneous measurements of expiratory minute volume, 59% of the ingested H₂ was exhaled. The loss of H₂ from the water during the experimental procedures accounted for 3% or less of the H₂. H₂ release from the skin surface was estimated as approximately 0.1%. Based on the remaining H₂ mass balance, approximately 40% of the ingested H₂ was consumed in the body. As the H₂ molecule is reported to be a weak scavenger of hydroxyl radicals and is not effective against superoxide or hydrogen peroxide, the rate of hydroxyl radical production was estimated to be at least 1.0 μmol/min/m² (equivalent to 29 nmol/min/kg), assuming that the H₂ molecules were all used to scavenge hydroxyl radicals and that bacterial consumption in the alimentary tract and on the skin surface could be excluded. In summary, 59% of ingested H₂ was exhaled, and most of the remainder was consumed in the body.