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

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: Completed
• Conditions: Health Behavior
• Intervention / Treatment: Dietary supplement: Kombucha beverage

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: Interventional
• Enrollment (Actual): 31
• Phase: Not Applicable

Contacts and Locations

Study Locations

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

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

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)	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

Outcome Measure	Measure Description	Time Frame
Change in fasting blood glucose levels at time point 2 from baseline (week 0)	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)	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)	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)	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)	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)	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)	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)	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

• Sponsor: University of California, San Diego
• Collaborators: GT's Living Foods
• Investigators: Principal Investigator: Jack A Gilbert, Ph.D., UC San Diego

Study record dates

Study Major Dates

• Study Start (Actual): March 3, 2022
• Primary Completion (Actual): December 1, 2022
• Study Completion (Actual): April 25, 2024

Study Registration Dates

• First Submitted: June 7, 2024
• First Submitted That Met QC Criteria: July 1, 2024
• First Posted (Actual): July 3, 2024

Study Record Updates

• Last Update Posted (Actual): July 3, 2024
• Last Update Submitted That Met QC Criteria: July 1, 2024
• Last Verified: July 1, 2024

More Information

Terms related to this study

• Keywords: Inflammation; Microbiome; Biochemical indicators
• Other Study ID 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