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

February 12, 2026 updated by: Universidade Nova de Lisboa

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

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
30

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

  • Name: André Rosário, PhD
  • Phone Number: +351 218 803 053

Study Locations

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

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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).
Time Frame: 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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
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).
Time Frame: 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).
Time Frame: 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).
Time Frame: 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).
Time Frame: 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).
Time Frame: 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).
Time Frame: 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).
Time Frame: 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).
Time Frame: 4 weeks
Change in urinary pH evaluated by the urine pH before and after intervention.
4 weeks

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Adverse events
Time Frame: 4 weeks
Registration of any adverse events.
4 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Universidade Nova de Lisboa

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
CINTESIS - Center for Health Technology and Services Research

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • 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

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 5, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
October 25, 2023

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 20, 2023

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
May 11, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 11, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
May 16, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 17, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 12, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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Conditions

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