How effective is drinking natural mineral water against heartburn from functional dyspepsia, gastroesophageal reflux disease or other causes? A systematic review of clinical intervention studies.

Background For centuries, spring and other natural waters have been recommended as external or internal remedies for numerous diseases. For studies that examined the effects of drinking mineral waters against heartburn, gastroesophageal reflux disease (GERD), or functional dyspepsia a systematic review is lacking. Objectives The main aim of this systematic review was to examine the effects of drinking natural mineral waters on heartburn from various causes by identifying all published intervention studies and critically appraising their methods as well as summarizing their results. Methods We systematically searched the largest medical literature database MEDLINE, further relevant web sources and gray literature for randomized and non-randomized trials, with or without control groups, up to September 2021 and no language restrictions. Further inclusion criteria were adult patients with heartburn, drinking cure with natural mineral water as intervention, compared to no or other interventions (care-as-usual, waiting list). We defined the reduction of heartburn symptoms and duration of disease episodes as primary and quality of life as secondary outcomes. Two reviewers independently carried out the study quality assessments (risk of bias) using the National Institutes of Health-Study Quality Assessment Tools. Results Nine trials comprising 393 patients from Italy, Russia, Ukraine, and Germany fulfilled all inclusion criteria. We identified three randomized controlled trials (all with poor methodological quality), plus six before-after (pre/post) intervention studies without a control group. The intervention groups of the three comparative trials seemed to show a stronger reduction of self-reported heartburn symptoms, and duration of heartburn episodes than the respective control groups, however they all had a poor methodological quality. Conclusion Based on the best available evidence of clinical studies, we cannot recommend or advise against drinking natural mineral waters as a treatment for heartburn. The potential benefits of natural mineral waters that were reported in some studies with a lower evidence level (e.g., lacking a control group) should be verified by good quality randomized clinical trials with adequate comparison groups and longer follow-up periods. .