The Effect of Natural Carbonated Mineral Water Consumption on Gastrointestinal Transit and Gut Microbiota - A Randomized Controlled Trial

Gastrointestinal discomfort is a common condition associated with aging, low levels of physical activity, and reduced intake of fibre, water, and magnesium. Several studies have reported a positive association between the consumption of hyper-mineral water containing high levels of bicarbonate, calcium, or magnesium and improvements in gastrointestinal transit. There is evidence that magnesium and sulphate, individually, exert a laxative effect; however, the impact of other minerals remains limited.

Different mechanisms have been described to explain how the gut microbiota influences gastrointestinal transit. It is important to understand the characteristics of the gut microbiota and to determine whether the intake of hyper-mineral water, a natural source of minerals, can positively modulate it.

The aim of this randomized, placebo-controlled trial is to evaluate the effects of carbonated mineral water consumption on gastrointestinal transit and gut microbiota composition.

Study Overview

• Status: Completed
• Conditions: Gastrointestinal Discomfort
• Intervention / Treatment: Other: Natural Carbonated Mineral Water; Other: Low Mineral Water

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Portugal
  • Lisbon, Portugal, 1169-056
    • NOVA Medical School | Faculdade de Ciências Médicas da Universidade NOVA

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age between 18 and 70 years
• History of gastrointestinal discomfort
• Not using any laxative drug for 3 days before the screening visit
• Drinking 1.0 ± 0.5 L of water per day
• Accepting and signing the informed consent

Exclusion Criteria:

• Treatment or disease (current or past) likely to interfere with evaluation of the study parameters
• Taking antibiotics in the 3 months preceding the recruitment visit
• Taking supplements or any food enriched with or containing bacteria or yeasts likely to have an effect on the gastrointestinal tract, particularly on intestinal transit, digestive comfort, gas production, or the occurrence of abdominal pain, in the 30 days preceding the recruitment visit (these products will also be banned during the study period)
• Subject having an alcohol consumption of more than 3 glasses of wine per day, or 2 glasses of beer per day, or 1 glass of hard liquor per day
• Subject having a coffee consumption greater than 5 cups per day
• Subject with constipation attributable to an organic or anatomical cause (Hirschsprung's disease, hypothyroidism, mental deficiency, psychiatric illness, neurological abnormalities, history of operation of the colon or anus, colorectal cancer, anemia, etc.)
• Subject with a history of current gastrointestinal pathology or disorder such as duodenal ulcer, chronic colitis, or chronic inflammatory disease of the gastrointestinal tract (Crohn's disease, ulcerative colitis), celiac disease, or irritable bowel syndrome
• Subject having a history of operation of the digestive tract
• Subject having undergone surgery in the two months preceding the recruitment visit
• Subject having undergone bariatric surgery
• Having participated in a weight loss program (with a 5-10% weight loss) in the last 3 months prior to the recruitment visit
• Body mass index > 35 kg/m²
• Taking supplements of magnesium, vitamins, or other minerals during the study period
• Intake of other carbonated mineral waters beyond the provided water during the study period
• Pregnancy
• Participation in another clinical trial during the last 30 days prior to the recruitment visit

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Carbonated Natural Mineral Water; Participants consume 1000 mL per day of natural carbonated mineral water throughout the 4-week study period.	Other: Natural Carbonated Mineral Water; Participants consume 1000 mL per day of natural carbonated mineral water for 4 weeks, divided into four portions: before breakfast, 30 minutes before lunch, during the afternoon, and 30 minutes before dinner. Any additional water intake, if desired, is provided by the study investigators and consists exclusively of low-mineral water in both study arms. Participants record their total weekly water consumption using an electronic form.
Placebo Comparator: Low Mineral Water; Participants consume 1000 mL per day of low-mineral water throughout the 4-week study period.	Other: Low Mineral Water; Participants consume 1000 mL per day of low-mineral water for 4 weeks, divided into four portions: before breakfast, 30 minutes before lunch, during the afternoon, and 30 minutes before dinner. Any additional water intake, if desired, is provided by the study investigators and consists exclusively of low-mineral water in both study arms. Participants record their total weekly water consumption using an electronic form.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference between the intervention and control group in the change in gastrointestinal transit from baseline to the end of follow-up (4 weeks).	Change in gastrointestinal transit measured by the percentage of responder subjects defined as a composite score of the two following Rome IV criteria: number of stools ≥ 4 or an increase of 2 stools/week and stools consistency with less than 25% of lumpy to hard stools.	4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference between the intervention and control group in the change in stool consistency from baseline to the end of follow-up (4 weeks).	Change in stool consistency measured using Bristol scale.	4 weeks
Difference between the intervention and control group in the change in constipation symptoms from baseline to the end of follow-up (4 weeks).	Change in constipation symptoms measured using a validated PAC-SYM questionnaire. PAC-SYM is a 12-item, self-administered questionnaire used to measure severity of symptoms over the past 2 weeks in patients with constipation. Cultural adaptation and linguistic validation of the PAC-SYM for Portugal was performed by Mapi Research.	4 weeks
Difference between the intervention and control group in the change in constipation Quality of Life from baseline to the end of follow-up (4 weeks).	Change in constipation Quality of Life measured using a validated PAC-QOL questionnaire. PAC-QOL questionnaire is a 28-item self-administered questionnaire that is being used to measure health-related quality of life (over the past 2 weeks) in patients with chronic constipation. Cultural adaptation and linguistic validation of the PAC-QOL for Portugal was performed by Mapi Research Trust.	4 weeks
Difference between the intervention and control group in the change in Perceived Stress Scale from baseline to the end of follow-up (4 weeks).	Change in constipation Perceived Stress Scale measured using a validated Perceived Stress Scale questionnaire. A validated Perceived Stress Scale (PSS) self-administered questionnaire with 13-item will be used to measure perceived stress of respondents during the last month (Portuguese version keeps 13 of the 14 original items). The PSS questionnaire has been demonstrated to have internal consistency, reproducibility, validity, and sensitivity. Cultural adaptation and linguistic validation of the PSS for Portugal was implemented by Pais-Ribeiro & Marques (2009).	4 weeks
Difference between the intervention and control group in the change in gut microbiota from baseline to the end of follow-up (4 weeks).	Bacterial DNA will be extracted from fecal samples. 16SRNA gene will be sequenced by next-generation sequencing (NGS). All the identified bacterial phyla, genus and species will be expressed in percentage.	4 weeks
Difference between the intervention and control group in the change in short-chain fatty acid profiling from baseline to the end of follow-up (4 weeks).	Change in short-chain fatty acid profiling evaluated by the faeces concentration of short-chain fatty acids before and after intervention.	4 weeks
Difference between the intervention and control group in the change in urinary excretion of minerals from baseline to the end of follow-up (4 weeks).	Change in urinary excretion of minerals evaluated by the K+, Na+, Mg2+ and Ca2+ excretion before and after intervention.	4 weeks
Difference between the intervention and control group in the change in urinary pH from baseline to the end of follow-up (4 weeks).	Change in urinary pH evaluated by the urine pH before and after intervention.	4 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Adverse events	Registration of any adverse events.	4 weeks

Collaborators and Investigators

• Sponsor: Universidade Nova de Lisboa
• Collaborators: CINTESIS - Center for Health Technology and Services Research
• Investigators: Study Director: André Rosário, PhD, NOVA Medical School | Faculdade de Ciências Médicas da Universidade Nova de Lisboa; Study Director: Inês Mota, NOVA Medical School | Faculdade de Ciências Médicas da Universidade Nova de Lisboa; Principal Investigator: Conceição Calhau, PhD, NOVA Medical School | Faculdade de Ciências Médicas da Universidade Nova de Lisboa

Study record dates

Study Major Dates

• Study Start (Actual): April 5, 2023
• Primary Completion (Actual): October 25, 2023
• Study Completion (Actual): November 20, 2023

Study Registration Dates

• First Submitted: May 11, 2022
• First Submitted That Met QC Criteria: May 11, 2022
• First Posted (Actual): May 16, 2022

Study Record Updates

• Last Update Posted (Actual): February 17, 2026
• Last Update Submitted That Met QC Criteria: February 12, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Signs and Symptoms, Digestive; Constipation
• Other Study ID Numbers: MineralWaterGut

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data (IPD) from this study will not be publicly shared because the ethics committee has limited their use to the approved research project. However, anonymised partial data sets or summary data may be made available upon reasonable request.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No