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December 4, 2021Hydrogen-Rich-Water And Gut Microbiome
In mammals, the gut microbiome forms a complex ecosystem consisting of a vast number of interacting bacteria, archaea, bacteriophages, eukaryotic viruses, and fungi, most of which are commensal or mutualistic microorganisms. In the past decade, the gut microbiota has proved to play a profound role in the modulation of host immunity, food digestion, regulating gut endocrine function and neurological signaling, modifying drug action and metabolism, eliminating toxins, and producing numerous compounds that influence the host. That the gut microbiome having important effects on human health is now well-known. However, its importance inhealthy aging is just starting to be uncovered. A recent study published in Nature Metabolism examined the gut microbiome patterns of 9000 individuals aged 18 to 101, showing that microbiome health reflects healthy aging and is able to predict human survival. The data showed that individuals’ gut microbiomes became increasingly unique (i.e., increasingly divergent from others) as they aged, starting in mid-to-late adulthood, and this corresponded with a steady decline in the abundance of core bacterial genera (e.g., Bacteroides) that tend to be shared across humans. In the later decades of human lifespan, healthy individuals continued to show an increasingly unique gut microbial composition with age, whereas this pattern was absent in those in worse health. In individuals above 85 years old, retention of high relative Bacteroides abundance and a low gut microbiome uniqueness measure were both associated with significantly decreased survival in the course of a 4-year follow-up.
Research studies on HRW and gut microbiome
Preliminary findings suggest that HRW may positively affect the gut microbiome. A They found that oral gavage with hydrogen-water protects mice against radiation-induced toxicity, significantly improving the gastrointestinal tract functions and epithelial integrity after abdomen irradiation. The researchers reported that the way that hydrogen water does so is by increasing the level of a microRNA (miR-1968-5p) in the mouse small intestine, thereby downregulating the expression of MyD88 (myeloid differentiation primary response gene 88, an essential modulator of the innate immune response to microbial pathogens). Importantly, the hydrogen-water treatment resulted in retention of the intestinal bacterial composition even after irradiation. Another research study published in 2018 specifically investigated the effects of HRW on the intestinal environment, including microbial composition and short-chain fatty acids. Here, mice were administered HRW (H2 0.32 mM) or normal water for 4 weeks. The results showed that the relative abundances of 20 taxa differed significantly in HRW-administered mice. Specifically, drinking HRW favored a lower relative abundance of Bifidobacterium, Clostridiaceae, Coprococcus, Ruminococcus, and Sutterella, and a higher abundance of Parabacteroides, Rikenellaceae, Butyricimonas, Prevotella, and Candidatus arthromitus. Although the exact role of each of these species remains to be investigated, they are overall associated with cholesterol metabolism and liver health, highlighting the possibility that oral intake of HRW has beneficial effects on the microbiome.
Other studies in rats, piglets, and mice have all demonstrated beneficial effects of HRW on the microbiome. Interestingly, a 2019 study conducted in a rat model of Parkinson’s disease showed that treatment with hydrogen-rich water produced via electrolysis was protective against permethrin (PERM) (a pesticide used to induce Parkison’s in animal models). The treatment led to higher abundances of butyrate-producing bacteria such as Blautia, Lachnospiraceae family, Ruminococcaceae family, Papillibacter, Roseburia, Intestinimonas, Shuttleworthia, together with higher butyric acid levels. Animal models of Parkinson’s have demonstrated that butyrate administration improves motor deficits, reduces inflammation and dopamine deficiency. Therefore, since there is accumulating evidence that the origin of the disease may lie in the gut, hydrogen water position itself as a promising strategy to investigate further.
Human studies investigating HRW effects on microbiome
The first human randomized clinical trial investigating how drinking HRW affects the gut microbiome was published in 2019. In this first-in-human study, 38 juvenile female football (soccer) players were subjected to a 2-month HRW drinking protocol (1.5–2.0 L/day). The results showed a significant increase in antioxidant capacity, as indicated by increased serum superoxide dismutase, total antioxidant capacity levels, and hemoglobin levels of whole blood. During intense exercise, inflammatory factors usually increase due to the increase in energy consumption, free radicals, and the intensification of oxidative stress. After 8 weeks of hydrogen-rich water treatment, the levels of IL-1, IL-6, and TNF-α (e.g., inflammatory markers) in the hydrogen-rich water treatment group were significantly lower than those in the control group, showing that long-term hydrogen-rich water treatment led to a strong anti-inflammatory effect in addition to an antioxidant effect. In addition, the consumption of HRW improved the diversity and abundance of the gut flora in the athletes, which is an indicator of a more favorable microbial balance.
Another recent double-blind, randomized trial assessed the effects of ingestion of hydrogen-rich water produced via electrolysis on stool consistency and gut microbiota in healthy individuals who are not subject to intense oxidative stress due to factors such as excessive exercise. The participants drank 500 mL of purified tap water or HRW every day for 2 weeks. The relative abundance of the Bifidobacterium genus significantly increased in the HRW group. Among Bifidobacterium, Bifidobacterium longum and Bifidobacterium adolescentis both showed a significant increase. In addition, the HRW group saw their stool consistency significantly converge to the Bristol Stool Scale (BSS) Type 4 (“normal”). It has been previously reported that there is a clear relationship between gut microbiota and stool consistency, and by having humans ingest Bifidobacterium in the form of tablets, the gut microbiota composition was transformed, and stool consistency was normalized.
Microbiome and COVID-19
Although COVID-19 is primarily a respiratory illness, there is mounting evidence suggesting that the gastrointestinal tract is involved in this disease. A recently published study found that the gut microbiome composition in patients with COVID-19 was significantly altered compared with individuals without COVID-19. Importantly, this difference was observed regardless of whether the patients have received any medication. In COVID-19 patients, several gut commensals with known immunomodulatory potential such as Faecalibacterium prausnitzii, Eubacterium rectale, and bifidobacteria were underrepresented and remained low in samples collected up to 30 days after disease resolution. Moreover, this altered composition was correlated with the severity of the disease and the levels of inflammatory cytokines and blood markers of tissue damage, suggesting that the gut microbiome might be involved in the magnitude of the disease by modulating the host immune response. In this context, based on the ability of hydrogen water to improve the gut microbiome, it could justify research as a potentially easily implementable therapeutic strategy in COVID-19 patients- however, this is merely speculation, and would need direct and significant evidence to support use.
To sum up
The microbiome is essential for human health, and research findings suggest that the more diverse it is, the better. There is preliminary evidence from pre-clinical and clinical studies that HRW may positively affect the gut microbiome, including increasing its diversity. Further, more robust clinical trials will elucidate this exciting avenue further.