However, although improvements were observed after two weeks, between-group differences at the end of the study period (three weeks) were not significant.
Noting a good safety profile and perceived reduction in laxative use, researchers from Germany and France suggested the mineral water may be a “supportive, non-pharmacological dietary measure in individuals suffering from chronic constipation”.
How minerals may improve bowel movements
Chronic constipation refers to symptoms present for at least 3 months, including fewer bowel movements and stools that are more difficult to pass. Functional constipation is chronic constipation without a known cause but heavily influenced by the gut-brain axis.
Sulfate and magnesium can cause osmotic water influx into the gastrointestinal tract, softening the stool and making it easier to pass. The intestines absorb these mineral ions slowly and incompletely, thereby promoting this osmotic effect.
The study also notes that magnesium sulfate increases the expression of regulators of colonic water transport and modulates osmotic pressure in the colon.
“Other proposed pathways include the stimulation of cholecystokinin (CCK), peptide YY (PYY), and nitric oxide synthase (NOS), which may enhance intestinal motility and relax circular smooth muscle cells,” the researchers wrote.
Study details
The study was a parallel-group, randomized, double-blind, controlled trial conducted in several waves between September 2024 and March 2026.
157 healthy German adults (144 women, 13 men) aged 18 to 75 with chronic constipation began each wave with a 7-day run-in phase during which they consumed 1,500–2,000 mL/day of low-mineralized spring water.
During the following three intervention weeks, they were asked to drink 1,000 mL/day of the respective study water: sulfate- and magnesium-rich mineral water (HSM water) or low-sulfate and low-magnesium mineral water (LSM water).
The HSM water, provided by St Antonin, which partly funded the study, contained 1,450 mg/L sulfate, 89 mg/L magnesium, and 568 mg/L calcium.
To meet the required daily fluid intake of 1500 mL, they were allowed to drink an extra 500 mL of the low-mineral water consumed during the run-in phase.
Severity of constipation was calculated using a Rome Score via a self-reported screening questionnaire.
Analysis of the results found that “the change from baseline to week two was significantly greater in the HSM group than in the LSM group”, the researchers wrote, noting this suggested a possible short-term effect at week two. Participants in the HSM group also perceived less laxative use.
However, there were no significant differences between the study groups at the end of the trial.
The researchers also observed an improvement in stool frequency despite a reduction in fiber intake, suggesting this may be attributable to the intervention, but noted that the results should be interpreted with caution.
They acknowledged the study limitations, such as self-reporting and awareness of the intervention due to taste differences from the control water.
Source: Frontiers in Nutrition; doi: https://doi.org/10.3389/fnut.2026.1924028; “Daily consumption of sulfate- and magnesium-rich mineral water enhances bowel function in adults with chronic constipation: a randomized double-blind real-world trial.” Authors: K. Mansouri et al.
