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Completed

NCT Number: NCT05375487

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.

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Key information

Conditions

Gastrointestinal Discomfort

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

NOVA Medical School | Faculdade de Ciências Médicas da Universidade NOVA

Lisbon, 1169-056, Portugal

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Natural Carbonated Mineral Water

Other

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.

Low Mineral Water

Other

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.

Primary outcomes

  1. 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.

Secondary outcomes

  1. 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.

  2. 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.

  3. 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. 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).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

Other outcomes

  1. Adverse events

    Time frame: 4 weeks

    Registration of any adverse events.

Sponsors and collaborators

Lead sponsor

Universidade Nova de Lisboa

Other

Collaborators

  • CINTESIS - Center for Health Technology and Services Research

Registry information

Important dates

Study start
2023
Primary completion
2023
Study completion
2023
First posted
May 16, 2022
Registry last updated
Feb 17, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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