Consumption of water containing over 3.5 mg of dissolved hydrogen could improve vascular endothelial function

Abstract

Background

The redox imbalance between nitric oxide and superoxide generated in the endothelium is thought to play a pivotal role in the development of endothelial dysfunction. A third reactive oxygen species (ROS), H₂O₂, is known to have both beneficial and detrimental effects on the vasculature. Nonetheless, the influence of the hydroxyl radical, a byproduct of H₂O₂ decay, is unclear, and there is no direct evidence that the hydroxyl radical impairs endothelial function in conduit arteries. Molecular hydrogen (H₂) neutralizes detrimental ROS, especially the hydroxyl radical.

Objectives

To assess the influence of the hydroxyl radical on the endothelium and to confirm that a gaseous antioxidant, H₂, can be a useful modulator of blood vessel function.

Methods

The efficacy of water containing a high concentration of H₂ was tested by measuring flow-mediated dilation (FMD) of the brachial artery (BA). The subjects were randomly divided into two groups: the high-H₂ group, who drank high-H₂ water containing 7 ppm H₂ (3.5 mg H₂ in 500 mL water); and the placebo group. Endothelial function was evaluated by measuring the FMD of the BA. After measurement of diameter of the BA and FMD at baseline, volunteers drank the high-H₂ water or placebo water immediately and with a 30-minute interval; FMD was compared to baseline.

Results

FMD increased in the high-H₂ group (eight males; eight females) from 6.80%±1.96% to 7.64%±1.68% (mean ± standard deviation) and decreased from 8.07%±2.41% to 6.87%±2.94% in the placebo group (ten males; eight females). The ratio to the baseline in the changes of FMD showed significant improvement (P<0.05) in the high-H₂ group compared to the placebo group.

Conclusion

H₂ may protect the vasculature from shear stress-derived detrimental ROS, such as the hydroxyl radical, by maintaining the nitric oxide-mediated vasomotor response.

Keywords:

• flow-mediated dilation
• reactive oxygen species
• molecular hydrogen
• hydroxyl radical
• 5–7 ppm
• peroxynitrite

Acknowledgments

We thank M Hanada and K Nagao for the technical support. We are grateful to R Kurokawa, S Hirano, T Seo, M Nagao, K Kiyota, and K Fukuoka for their excellent advice on the preparation of placebo water.

Author contributions

All authors made substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; took part in either drafting the article or revising it critically for important intellectual content; gave final approval of the version to be published.

Disclosure

The authors report no conflicts of interest in this work.