Daily consumption of sulfate- and magnesium-rich mineral water enhances bowel function in adults with chronic constipation: a randomized double-blind real-world trial

Introduction Functional constipation is one of the most common disorders of gut–brain interaction. Adequate hydration is recommended as first-line therapy, yet evidence regarding the efficacy of sulfate- and magnesium-rich mineral water remains limited. Therefore, this study investigated its efficacy and safety in a nationwide decentralized randomized controlled trial. Methods In this randomized, double-blind, controlled parallel-group trial, adults with chronic constipation according to the Rome IV criteria consumed either 1 L/day of sulfate- and magnesium-rich mineral water (HSM) or a low-mineralized control water (LSM) for 3 weeks following a one-week run-in period. Participants maintained a total daily fluid intake of at least 1,5L/day. The primary outcome was the change in weekly bowel movement frequency after 3 weeks. Additional analyses were conducted after 2 weeks of intervention. Secondary outcomes included stool consistency, responder rates, time to treatment response, constipation-related symptoms (PAC-SYM), constipation-related quality of life (PAC-QoL), gastrointestinal transit time, laxative use, and safety. Results After 2 weeks (additional analysis), bowel movement frequency increased significantly more in the HSM group than in the control group (mean change: 1.31 ± 3.24 vs. 0.34 ± 2.49 bowel movements/week; p = 0.043). This effect was more pronounced in participants with moderate-to-severe constipation ( p = 0.022). No significant between-group difference was observed at the end of week 3 ( p = 0.144). Time to treatment response was significantly shorter with HSM water than with control water (median 9 vs. 16 days; p = 0.042), accompanied by a higher responder rate in participants with moderate-to-severe constipation ( p = 0.043). No significant between-group differences were observed for stool consistency, constipation symptoms, quality of life, or gastrointestinal transit time. Both interventions were well tolerated, and only mild transient adverse events were reported. Discussion Daily consumption of 1 L of sulfate- and magnesium-rich mineral water, combined with adequate hydration, improved bowel movement frequency at week two and accelerated treatment response in adults with chronic constipation, whereas the between-group difference at the registered primary endpoint (week three) was not statistically significant. These findings suggest that sulfate- and magnesium-rich mineral water may serve as a safe, non-pharmacological dietary approach for the management of chronic constipation under real-world conditions. Clinical trial registration https://clinicaltrials.gov/ , DRKS00034871.