Effect of Kombucha Consumption on the Microbiome in Healthy Subjects (KOMICS)

July 1, 2024 updated by: Jack Gilbert, University of California, San Diego
This proposed pilot study will assess the ability of consumption of two servings of kombucha daily to decrease inflammation, alter the gut microbiome composition, and improve intestinal wellbeing in a free-living population. The primary objective is to determine changes in the fecal microbiome composition. Secondary outcomes will be bacterial metabolites (fecal indole propionic acid, calprotectin), serum interleukin (IL) 6, interleukin (IL) 10, C-reactive protein (CRP), C-peptide, insulin, fasting glucose, Homeostatic Model Assessment for Insulin Resistance (HOMA), 14-day continuous glucose monitor, digestive health, dietary information, general Health & Wellness at 4 and 8 weeks.

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.

Detailed Description

An altered intestinal gut microbiota, i.e. dysbiosis, has been associated with the development of intestinal disease including inflammatory bowel disease and metabolic diseases such as obesity, type 2 diabetes mellitus (T2DM), and cardiovascular disease. Fermented foods such as Kefir, Kombucha, Miso, and Kimchi contain potentially probiotic microorganisms. The characteristic microbiome in kombucha includes several genera of acetic acid bacteria, yeasts and lactic acid bacteria. Interactions between bacteria and yeast species can lead to the generation of a wide range of metabolites with interesting bioactivities such as organic acids, sugars, phenolic compounds. Kombucha produced from green and black tea contain many phenolic compounds, which contribute to its antioxidant and anti-inflammatory activity and effect on the intestinal microbiota. However, there is a lack of intervention trials investigating the health benefits of fermented foods. Therefore, the investigators propose a human intervention study to assess if daily consumption of two servings of kombucha will alter the intestinal microbiota, decrease inflammation, and improve digestive health in a two-phase design in a free-living population.

This will be a randomized, controlled, two arm intervention study. The study will be conducted in 30 healthy, free-living subjects (21-55 years). After 4-weeks of consuming a beige diet (i.e. low-fiber, low polyphenol diet), 20 subjects will consume one bottle (two servings) of kombucha daily for 4 weeks and 10 subjects will not change their dietary habits. At baseline (week 0), week 4 and 8, blood will be collected. On the day prior to the study visits at week 4 and 8, participants will collect a stool and bring it to the lab. On the day of study visit week 0, 4, and 8, body weight and composition will be determined, and questionnaires and 3-day food record will be collected.

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.
31

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 Locations

  • United States
    • California
      • La Jolla, California, United States, 92037
        • UC San Diego ACTRI

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

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Typically consume low fiber/polyphenol diet (beige diet)
  • BMI within 25-29.9 kg/m2

Exclusion Criteria:

  • Eating a high fiber/polyphenol diet or taking any medication or dietary supplement, which interfere with the absorption of polyphenols
  • History of gastrointestinal surgery, diabetes mellitus on medications, or other serious medical condition, such as chronic hepatic or renal disease, bleeding disorder, congestive heart disease, chronic diarrhea disorders, myocardial infarction, coronary artery bypass graft, angioplasty within 6 months prior to screening, current diagnosis of uncontrolled hypertension (defined as systolic BP >160mmHg, diastolic BP > 95mmHg), active or chronic gastrointestinal disorders, bulimia, anorexia, laxative abuse, or endocrine diseases (except thyroid disease requiring medication) as indicated by medical history or routine physical examination
  • Is unable or unwilling to comply with the study protocol
  • Using prebiotics, probiotics, yogurt, and/or any fiber supplements regularly
  • Taking antibiotics or laxatives within the past 3 months
  • Allergy or sensitivity to kombucha
  • In the opinion of the study investigator, any subject who demonstrate a risk of non-compliance with study procedure, or one who cannot read, understand, or complete study

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: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

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.
No Intervention: Control group
No intervention to be administered
Experimental: Kombucha group
Two servings of a 16 oz commercial kombucha beverage daily for four weeks
Dietary supplement: Kombucha beverage
After 4-weeks of consuming a beige diet (i.e. low-fiber, low polyphenol diet), 20 subjects (kombucha group) will consume one bottle (two servings) of kombucha daily for 4 weeks and 10 subjects (control group) will not change their dietary habits

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
Change in microbiome species richness and abundance of participants at time point 2 (week 8) from baseline (week 0)
Time Frame: Three time points which are baseline(week 0), time point 1(week 4) and time point 2 (week 8)
Shotgun metagenomic sequencing will be employed on fecal samples collected at three time points in the study period to capture the microbiome profile
Three time points which are baseline(week 0), time point 1(week 4) and time point 2 (week 8)

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
Change in fasting blood glucose levels at time point 2 from baseline (week 0)
Time Frame: Baseline (week 0) and time point 2 (week 8)
fasting glucose (mg/dL) will be measured from blood samples during the study
Baseline (week 0) and time point 2 (week 8)
Change in fasting blood insulin levels at time point 2 (week 8) from baseline (week 0)
Time Frame: Baseline (week 0) and time point 2 (week 8)
Fasting insulin (μU/mL) will be measured from blood samples during the study
Baseline (week 0) and time point 2 (week 8)
Change in fasting blood triglycerides levels at time point 2 (week 8) from baseline (week 0)
Time Frame: Baseline (week 0) and time point 2 (week 8)
Fasting triglycerides (mg/dL) will be measured from blood samples during the study
Baseline (week 0) and time point 2 (week 8)
Change in fasting blood cholesterol levels at time point 2 (week 8) from baseline (week 0)
Time Frame: Baseline (week 0) and time point 2 (week 8)
Total cholesterol, High density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol (mg/dL) will be measured from blood samples during the study
Baseline (week 0) and time point 2 (week 8)
Change in fasting blood glycated hemoglobin (HbA1C) at time point 2 (week 8) from baseline (week 0)
Time Frame: Baseline (week 0) and time point 2 (week 8)
Glycated hemoglobin (hbA1c) (%) will be measured from blood samples during the study
Baseline (week 0) and time point 2 (week 8)
Change in serum interleukin (IL)10 levels at time point 2 (week 8) from baseline (week 0)
Time Frame: Baseline (week 0), time point 1 (week 4) and time point 2 (week 8)
Measurement of serum interleukin (IL) 10 levels (pg/mL) by flow cytometry
Baseline (week 0), time point 1 (week 4) and time point 2 (week 8)
Change in serum interleukin (IL) 6 levels at time point 2 (week 8) from baseline (week 0)
Time Frame: Baseline (week 0), time point 1 (week 4) and time point 2 (week 8)
Measurement of serum interleukin (IL) 6 levels (pg/mL) by flow cytometry
Baseline (week 0), time point 1 (week 4) and time point 2 (week 8)
Change in serum C-reactive protein (CRP) levels at time point 2 (week 8) from baseline (week 0)
Time Frame: Baseline (week 0), time point 1 (week 4) and time point 2 (week 8)
Measurement of serum C-reactive protein (CRP) levels by flow cytometry
Baseline (week 0), time point 1 (week 4) and time point 2 (week 8)

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.
University of California, San Diego

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.
GT's Living Foods

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.
  • Principal Investigator: Jack A Gilbert, Ph.D., UC San Diego

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.
March 3, 2022

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.
December 1, 2022

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.
April 25, 2024

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).
June 7, 2024

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.
July 1, 2024

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.
July 3, 2024

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.
July 3, 2024

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.
July 1, 2024

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.
July 1, 2024

More Information

Terms related to this study

Keywords

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.
  • 210823

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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