Molecular hydrogen modulates brain glutamate/GABA-glutamine cycle in overweight humans

INTRODUCTION: We evaluated whether 12-week intake of molecular hydrogen (H(2)) in 5 overweight adults (3 women; age: 50.2 ±11.9 years, body mass index: 29.4 ±2.1 kg/m(2)) affects brain levels of the glutamate-glutamine-GABA cycle, critical amino acid neurotransmitters in the mechanism of neuronal activation during appetite regulation. METHODS: A 1.5-T single-voxel proton magnetic resonance spectroscopy was used to assess the tissue concentrations of relevant metabolites. RESULTS: The mean glutamate and glutamate-plus-glutamine levels at the posterior cingulate gyrus decreased significantly during the study; this was accompanied by a significant drop in GABA levels at left prefrontal white matter, and glutathione levels at anterior cingulate gyrus. No changes in the brain metabolites were found in the comparable group of overweight individuals (n = 4, 2 women; age: 41.0 ±13.9, BMI 26.8 ±1.3 kg/m(2)) followed-up in the past without this treatment. CONCLUSIONS: We showed a possible hydrogen-driven upregulation of neurotransmitters involved in appetite stimulation leading to hunger suppression and weight loss. Further studies analyzing appetite-controlling metabolic pathways affected by H(2) would require monitoring of additional biomarkers of satiation and satiety during different feeding regimens.