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Does much hyped alkaline electrolyzed water provide health benefits? A systematic review and narrative synthesis
Tejus Anantharamu1, R Vishnuprasad2, Sharmila Sinha3, D Santhanalakshmi4, Sapna Pradhan5, Fadil Salmani5
1 Regional Centre, ECHS Ranchi, Jodhpur, India
2 Station Health Organisation, Jodhpur, Maharashtra, India
3 Department of Pharmacology, Armed Forces Medical College, Pune, Maharashtra, India
4 Department of Physiology, Sri Venkateswaraa Medical College Hospital and Research Institute, Chennai, India
5 Department of Pharmacology, Army College of Medical Sciences, Delhi Cantt, India
| Date of Submission | 16-Mar-2022 |
| Date of Acceptance | 08-Aug-2022 |
| Date of Web Publication | 29-Nov-2022 |
Correspondence Address:
Dr. R Vishnuprasad
No: 22, Muthu Nagar, Muthirayarpalayam, Puducherry - 605 009
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/ijehe.ijehe_12_22
Alkaline electrolyzed water (AEW) usually has a pH value ranging from of 8 to 10, and is postulated to produce many health benefits. Alkaline water consumption still invites a lot of controversy among health professionals and researchers. There were no comprehensive large-scale studies till date that compared the effects of AEW across various disease states targeting multiple system changes as outcomes. The present literature review was carried out to collate all the available clinical research works on Alkaline Water or AEW in improving disease state or promoting health. Search in various databases and search engines brought out 19 articles, of which nine met the eligibility criteria and were included for the analysis in the present study. The risk of bias and quality for every study included in the study were assessed. For all the randomized trials included in the study bias assessment was carried out using the Cochrane Risk-of-bias tool, and nonrandomized trials were assessed using nonrandomized studies of interventions tool. Reviewed studies have reported effects of AEW on oxidative stress, gastric cancer, blood sugar levels, exercise performance, blood viscosity, and gastrointestinal symptoms. AEW has shown considerable positive health effects in small-scale clinical studies. However, presently available evidence from the research works are not sufficient enough for recommendation to the mass in general or for use as a therapeutic intervention. Research works with larger study samples and among population of different demography are required.
Keywords: Alkaline electrolyzed water, anti-oxidant, drinking water, health effects, pH
How to cite this article:
Anantharamu T, Vishnuprasad R, Sinha S, Santhanalakshmi D, Pradhan S, Salmani F. Does much hyped alkaline electrolyzed water provide health benefits? A systematic review and narrative synthesis. Int J Env Health Eng 2022;11:12 |
How to cite this URL:
Anantharamu T, Vishnuprasad R, Sinha S, Santhanalakshmi D, Pradhan S, Salmani F. Does much hyped alkaline electrolyzed water provide health benefits? A systematic review and narrative synthesis. Int J Env Health Eng [serial online] 2022 [cited 2023 Apr 2];11:12. Available from: https://www.ijehe.org/text.asp?2022/11/1/12/362222 |
| Introduction | |  |
Water is a vital need for maintaining cellular homeostasis as it constitutes almost 75% of body weight in infants and up to 55% in the elderly. Variation in water intake has been linked to human health, and performance.[1] Chemicals present in polluted water on consumption are known to induce oxidative stress.[2] It is suggested that advancing age and diet, induces chronic low-grade metabolic acidosis that can bring about a small decrease in pH and bicarbonate in plasma. To counter the same, the consumption of naturally occurring alkaline water and alkaline electrolyzed water (AEW), also known as electrochemically reduced water (ERW) that exhibits an alkaline pH (usually in the range of 8–10), rich in hydrogen molecules, has negative oxidative reduction potential and possess scavenging activity on reactive oxygen species (ROS) has been widely promoted in the recent past.[2],[3] The functional water association of Japan defines functional water as the water that is activated (either by electrolysis, bubbling with gases, irradiation, ultrasonication, or treatment with magnetic field/some minerals) and produces useful functions that can be demonstrated and reproduced scientifically.[3],[4] Electrolysis is performed by flowing the normal water filtered through carbon filters, into an electronic chamber containing an anode and cathode separated by a diaphragm. The water produced from cathode of the electrolytic chamber is rich in H2 with a pH of 8–10 is called AEW or ERW and the water produced from the anode will be rich in H+ with a pH of 4–6 is called acidic electrolyzed water or electrochemically oxidized water (EOW).[3],[4] The appliances that can electrolyze drinking water have been used extensively in Japan and Taiwan for domestic purposes.[3],[4] EOW is used in the food industry (especially for the processing of seafood) as a sanitizer.[5] AEW is postulated to produce many health benefits, especially in relieving gastrointestinal symptoms, reducing the incidence of cardiovascular diseases, cancer, osteoporosis, total mortality rates, and preserve insulin-producing beta cells of the pancreas by its antioxidant effects.[2],[3],[4],[5],[6] In Japan, these devices have been approved as medical devices as early as 1965 by the Ministry of Health, Labour and Welfare. The timeline of history, development and approval of such appliances has been presented [Figure 1]. As no universal recommendation exists for using AEW in humans, preclinical studies would play a vital role in providing guidance for future research.[7],[8],[9],[10],[11],[12],[13],[14],[15],[16] Use of these appliances has been ever increasing in Europe, but are imported under the label of the European Commission but are still not approved as a medical device.[3] Although many preclinical studies and some clinical studies have been reported, but till date, no systematic review has been conducted to evaluate the overall health benefits of AEW. Health benefit is a positive effect on a person's health gained from food, treatment, or an activity, in this case, AEW. Since the studies available did not have common objective or a specific health benefit as an outcome of interest, the present study was planned as a narrative review. The purpose of this narrative review is to conduct an elaborate search on all the existing literature to determine the strength of evidence available for using AEW to gain health benefits and summarize the evidence, to make recommendations on the use of AEW. | Figure 1: History of development of electrolyzed alkaline drinking water
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| Methods | | |
The review follows Preferred Reporting Items for Systematic Review and Meta-analysis guidelines. A comprehensive search for all the eligible studies published in English language on the use of AEW/EAW and health benefits was conducted on PubMed, Cochrane library, Scopus, Elsevier, OVID Medline, EBSCO, and Clinical trials. Gov and Google scholar databases until October 31, 2020, using “([Alkaline electrolyzed drinking water] OR [Electrochemically reduced drinking water] OR [Alkaline drinking water] OR [Alkaline reduced water] AND [Human health] OR [Health benefits] OR [Disease])” as key words. Any timeline could not be set as the first approved apparatus producing AEW dates back to 1965. The references of the eligible studies were searched manually for any studies that might have missed our search strategy. For the identification and inclusion of studies, we defined participants, exposure, comparator, outcome (s), and type of study.
Two authors (TA and VR) reviewed the abstracts of all the results obtained from all search engines. All studies conducted in adults aged more than 17 years and older (Population of interest) utilizing AEW/EAW (exposure) obtained from an ionizer apparatus for consumption to demonstrate health benefit (outcome) in comparison to normal water (comparator), with a prospective study design (study design) were selected for review. All those studies not concerned or related to the subject of interest (includes those studies conducted using acidic electrolyzed water, and neutral electrolyzed water), those studies demonstrating benefit in food and agricultural field (without intervention on humans) and all preclinical studies were excluded as schematically depicted in [Figure 2]. The selected research works were studied separately by the authors TA and VR and all those studies with the availability of full texts were selected. In case of any ambiguity third and fourth authors (SS and PM) were consulted, and finally, a consensus decision was taken. Those articles without full manuscripts and duplicates from various search engines were excluded. All the selected studies were forwarded for data extraction. | Figure 2: Flow chart of identification of studies, their inclusion and exclusion
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One author (TA) extracted data from all the selected studies by using data extraction forms that were prespecified. Data extracted included country of study, year of publication, objective (s), methods (including study population, mean age in years, sex in terms of male-to-female ratio, exposure, comparator, and design of the study), outcome (s), results, risk of bias, and quality assessment. The second author (VR) assessed the correctness and completeness of the data extracted from the selected studies. The third and fourth authors (SS and PM) again reviewed the correctness of the data extracted from selected studies. Any discrepancies were settled by discussions among all.
Two authors (TA and VR) independently assessed the risk of bias and quality for every study included in the study. For all the randomized trials included in the study, bias assessment was carried out using Cochrane risk-of-bias tool and nonrandomized trials were assessed using the nonrandomized studies-of interventions tool.[17],[18],[19],[20] The quality of evidence for each outcome in included studies was assessed using the Grading of Recommendations Assessment, and Development of Evaluation approach.[20] Any difference in the assessment of risk or quality of evidence between two assessors was discussed with the third and fourth authors (SS and SD), and a consensus was reached.
| Results | | |
Extensive literature search in various different databases and search engines brought out nine research publications that are eligible for review as per the predefined eligibility criteria. Majority of the articles focused their area of exploration in gastrointestinal (GI) effects of the healthy and diseased population (four studies), followed by its effects on Type II Diabetes Mellitus (T2DM), while others focused on its effects on high-intensity exercise or sports. The quality of evidence from these studies was graded low considering the relatively lesser sample size studied in these research works and the study design/methods employed. The reviewed studies are outlined in [Table 1].
In patients with irritable bowel syndrome, improvement in symptoms and quality of life (QoL) were noted among the study participants who consumed at least 2 L of ARW per day for 8 weeks in the study by Shin et al.[21] In another study by Chaves et al.,[22] 50 individuals more than 35 years of age consumed alkaline water (pH- 8.5–10) obtained from ionizer for 5 months. It was observed after intervention that there was a statistically significant increase in expression of miR-29c (P = 0.039) and miR-135b (P = 0.039) and 43% (n = 12) with prior moderate gastritis were categorized as mild gastritis (P = 0.024). A statistically significant difference (P < 0.05) for whole body reaction time in users of AEW and a significant difference in the quality of sleep (P < 0.01) in the AEW group was reported by Tanaka et al.[23] after an intervention period of 4 weeks. On the contrary, Hansen et al.,[24] who studied gut microbial community after 2 weeks of intervention with alkaline water, stated that they did not observe an effect on overall diversity as represented by Shannon's index. Furthermore, no effect was observed for OTU-based richness, estimated richness (Chao 1), or Simpson's reciprocal index when comparing the alkaline and neutral water interventions.
Rias et al.[25] in their research work among patients with T2DM reported that the concentration of advanced glycation end products, advanced oxidation protein products and malondialdehyde measured by ELISA showed significant (P < 0.001) reductions in intervention groups (AEW) as compared to control. Furthermore, white blood cell count and neutrophil–lymphocyte ratio from fasting blood samples showed significant (P < 0.001) reductions in intervention groups. Chycki et al.[26] observed a significant decrease in LA, increase in K+, urine pH and a decrease in SG, postexercise among those who were given AEW as compared to controls. Rias et al.'s[25] study reported that QoL (using 36-item short form survey, includes total QoL, mental component score, and physical component score) assessments depicted that the AEW group at 8 weeks highly significant changes in total QoL and physical component score (No changes in mental component score), while AEW and the walking group showed highly significant changes in all three score, whereas the control group showed no significant changes in any of the scores. A study also reported that consumption of AEW after exercise-induced dehydration reduced high-shear viscosity; however, plasma osmolality, bioimpedance, and body mass did not change significantly.[27] Significantly higher reduction on random blood glucose values was noted among T2DM patients who consumed AEW with pH.9.0 as compared to groups who received AEW with pH 8 and 7, in the study by Siswantoro and Purwanto.[28]
| Discussion | | |
The pH level is a number that measures how acid or base, a substance is, on a scale of 0–14. The pH values of majority of the bottled waters were found to be predominantly acidic. Also, these bottled waters when tested, had a more acidic pH than the value enumerated in their water quality reports.[30] AEW usually has a pH value ranging from of 8 to 10. Alkaline water consumption still invites a lot of controversy among health professionals and researchers. There were no comprehensive large-scale studies till date that compared the effects of AEW across various disease states targeting multiple system changes as outcomes. Oxidative stress, gastric cancer, blood sugar levels, exercise performance, blood viscosity, and GI symptoms were parameters evaluated in the available studies. The present literature review was carried out to collate all the available clinical research works on Alkaline Water or AEW in improving disease state or promoting health. Search in various databases, and search engines brought out 19 articles, of which nine met the eligibility criteria and were included for the analysis in the present study. Most of the available literature on the subject are of a small sample size or without a control comparison group.
For the management of functional GI disorders, various different preclinical researches have been carried out in the past, which showed positive results.[31],[32],[33] Possible explanation for the same could be the neutralization effect of gastric acid by bicarbonate ions in alkaline water, which in turn may alter the intestinal flora, resulting in changes of the gastrointestinal activities.[34] While it is a known fact that the acidic environment of the duodenum aggravated adverse GI symptoms,[35] it is also vital that the physiological pH of the proximal duodenum is maintained. Various mineral salts and ions may stimulate GI smooth muscles to improve GI motility.[36] A state of oxidative stress is said to exist when there is excess ROS beyond neutralizing anti-oxidant capacity. Oxidative stress plays a vital role in the pathogenesis of many chronic diseases, by provoking inflammatory response to cellular damage. Reducing the ability of hydrogen ions in AEW, contribution to neutralization of ROS, can be ascribed to its beneficial effects in a state of oxidative stress.[37] It can be assumed that AEW indirectly, improves the quality of sleep and physical performance by reducing oxidative stress. These improvements ultimately result in a better QoL. Oxidative stress is believed to play an important role in the pathophysiology of diabetes mellitus as well.[38] Consumption of water rich in hydrogen has been found to improve glucose and lipid metabolism in patients with diabetes mellitus.[39] There is no evidence at present that demonstrates negative impacts or adverse effects of consumption of alkaline water of various ranges, over a long period. Although it can contended that naturally occurring alkaline water has long been consumed by humans without any potential adverse events, it is important to study the long-term effects of alkaline water consumption in population that were not naturally exposed to these environments in the past. It is also important to study the cost factor involved in making the water alkaline vis-à-vis the benefits derived. Despite the mushrooming of water alkalinizing and purifying equipment in the market, there exists no strong evidence to either support or refute the use of alkaline water for drinking.
| Conclusion | | |
AEW has shown considerable positive health effects in small-scale clinical studies. However, evidence from existing research works is not sufficient enough for recommending AEW to be used for regular consumption or for therapeutic functions. The promotion and use of alkaline water as functional water is not justified. Research works with larger study samples and among different populations are required.
Acknowledgments
The authors extend their gratitude to their mentors for guidance and reviewing the research manuscript.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1]
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