The effects of hydrogen-rich water on gut microbiota and related health outcomes: A systematic review

Abstract

Background Hydrogen-rich water (HRW) has emerged as a promising therapeutic intervention due to its antioxidant and anti-inflammatory properties. Recent studies suggest that the ingestion of HRW may alter gut microbiota composition, potentially influencing various health outcomes such as metabolic, inflammatory, and neurological conditions. However, no comprehensive synthesis of the evidence exists. Objective This systematic review aims to evaluate and synthesize the available literature on the effects of HRW on gut microbiota composition and its associated health outcomes. Methods We conducted a systematic search of electronic databases, including PubMed, Scopus, Google Scholar, Cochrane Library, ProQuest, Web of Science, and Gray Literature. Results We included studies of human or animal populations exposed to HRW, focusing on randomized controlled trials, cohort studies, case-control studies, and relevant in vivo / in vitro studies. Two independent reviewers carried out data extraction, and they assessed the risk of bias using appropriate tools for each study design. We will synthesize the findings narratively to identify the impact of HRW on gut microbiota diversity and health-related outcomes such as metabolic, inflammatory, and immune system markers. Conclusion This review aims to provide a comprehensive understanding of HRW's effects on gut microbiota and its broader health implications, highlighting current evidence gaps and suggesting directions for future research.