Hydrogen as a Selective Antioxidant: a Review of Clinical and Experimental Studies

Abstract

Oxidative stress is implicated in the pathogenesis of many diseases; however, currently used antioxidants have a high toxicity that constrains administration to a narrow window of therapeutic dosage. There is a clear need for more effective and safer antioxidants. Diatomic hydrogen (H2) was proposed as a novel antioxidant that selectively reduces levels of toxic reactive-oxygen species. Recently, many studies have reported that H2 (inhaled or orally ingested, typically as approximately 0.8 mM H2-saturated water), can exert beneficial effects in diverse animal models of ischaemia–reperfusion injury, and inflammatory and neurological disease. In the clinic, oral administration of H2- saturated water is reported to improve lipid and glucose metabolism in subjects with diabetes or impaired glucose tolerance; promising results have also been obtained in reducing inflammation in haemodialysis patients and treating metabolic syndrome. These studies suggest H2 has selective antioxidant properties, and can exert antiapoptotic, anti- inflammatory and antiallergy effects. This review summarizes recent research findings and mechanisms concerning the therapeutic potential of H2.

Study details

Article type

Review

Disease / injury model

Ischaemia–reperfusion injury, metabolic syndrome, diabetes, Parkinson's, Alzheimer's, atherosclerosis, hepatitis, colitis, pancreatitis, sepsis, spinal cord injury, cancer, allergic diseases, haemodialysis, radiotherapy complications

Dose comparison

Different concentrations and volumes of hydrogen (e.g., 0.4 mM, 0.8 mM, 2% inhaled) and their effects are discussed, including comparisons between oral and inhaled administration.

Dose-dependent effect

Yes

Outcome

Mixed

Findings

This early review identifies that hydrogen (H2) acts as a selective antioxidant, reducing toxic reactive oxygen species without affecting physiological ROS. Both animal and clinical studies show H2 can reduce oxidative stress, inflammation, and apoptosis. H2 is non-toxic, well-tolerated, and offers advantages over conventional antioxidants.