Table 1.
H2 intake route and typical management schemes.
| Intake route | Advantages | Disadvantages | Subjects | Action time | Action effects | Intake protocol | References |
|---|---|---|---|---|---|---|---|
| Inhalation of H2 gas | Ensures the intake time and dose | May be explosive when the concentration is higher than 4% | Rats | 120 min | Inhibits cerebral I/R injury; antioxidant | 1, 2 or 4% H2 | Ohsawa et al. (2007) |
| Human | 7 days | Improves COPD symptoms | 66.6% H2 6-8h/d | Zheng Z. G. et al. (2021) | |||
| Rats | 4 months | Improves COPD symptoms; anti-inflammation | 41.6, 22 or 2% H2 once a day for 2 h | Liu et al. (2017) | |||
| Mice | 7 days | Improves asthma symptoms; anti-inflammation | 42% H2 twice a day, 2 h/day | Huang et al. (2019) | |||
| Human | Every day until discharge | Improves COVID-19 severity | 33.3% O2 and 66.6% H2 | Guan et al. (2020b) | |||
| Rats | 12 h | Alleviates acute pancreatitis; anti-inflammation | 2% H2 | Zhou et al. (2016) | |||
| Drinking H2-dissolved water | Portable and safe | Limited intake dose | Human | 2 weeks | Alleviates sports-related soft tissue injuries | H2-rich tablets, 2 g/day | Ostojic et al. (2014) |
| Guinea Pigs | 10 days | Ameliorates allergic rhinitis; immunoregulation | 20 μL/day introduced into nasal passage; 0.6 mmol/L | Xu et al. (2018) | |||
| Human | 4 weeks | Reduces inflammation and apoptosis of peripheral blood cells | 0.753 mg/L, 1,500ml/day | Sim et al. (2020) | |||
| Mice | 10 days | Alleviates EAE symptoms; anti-inflammation | 0.36 or 0.89 mM twice a day | Zhao et al. (2016) | |||
| Human | 8 weeks | Improves parapsoriasis en plaques | H2 water bathing twice a week, 10–15 min ever time | Zhu et al. (2018) | |||
| Rats | 60 or 90 min | Relieve retina injury; antiapoptotic | Saturated H2 eye drops | Oharazawa et al. (2010) | |||
| Injection of H2-dissolved saline | Ensures the dose and direct application to the affected area | Invasive and has the risk of cross-infection | Rats | 24 h | Alleviates inflammation and apoptosis in myocardial I/R injury | 0.6 mmol/L, 10 ml/kg | Yao L. et al. (2019) |
| Mice | 12 h | Attenuates sepsis-associated encephalopathy; anti-inflammation | 0.6 mmol/L, 5 mL/kg | Xie et al. (2020) | |||
| Rats | 2 h | Attenuates acute lung injury | 2.5 or 10 mL/kg | Zou et al. (2019) | |||
| Nanoparticle delivery | Safe and higher H2 content per unit volume | Expensive | Rats | 3 or 24 h | Attenuates myocardial I/R injury; anti-inflammation and antioxidant | 4×109 or 2×1010 bubbles | He et al. (2017) |