Kombucha in Overweight and Obese: Live Vs. Pasteurized Effects on Microbiota, Metabolism, and Liver Function (KOMBIOME)

Randomized Controlled Pilot Clinical Study Including Kombucha in the Diet of Individuals with Overweight and Class 1 Obesity: Comparative Assessment Between Live and Pasteurized Kombucha and Its Effects on Gut Microbiota, Metabolic Parameters, and Liver Function [FUSILLI Project -H2020]

Kombucha, a fermented beverage made from Camellia sinensis tea (black, oolong, or green) with sugar and a symbiotic culture of bacteria and yeast (SCOBY), has gained global attention for its potential health benefits. Factors like the type and amount of sugar substrate, fermentation time, and temperature significantly influence its organic compounds, total phenolics, vitamin content, and alcohol levels.

In a previous study, kombucha's impact on glucose tolerance, insulin sensitivity, body composition, and liver function was tested in male prediabetic mice with diet-induced obesity. Daily supplementation (200 µL per mouse) improved glucose tolerance after nine days (equivalent to one year in humans) and reduced liver steatosis, despite no changes in body composition.

Although kombucha has been associated with antioxidant, antimicrobial, probiotic, antidiabetic, and anticancer activities, strong scientific evidence in humans remains limited. Further clinical studies are needed to substantiate kombucha's health benefits in humans.

Study Overview

• Status: Recruiting
• Conditions: Obesity and Overweight
• Intervention / Treatment: Dietary supplement: Live kombucha (non filtered/ non pasteurized); Dietary supplement: Pasteurized kombucha (non filtered); Other: Control (sparkling water)

Detailed Description

The objectives of this clinical study aim to explore the effects of kombucha on the health of individuals with overweight and class 1 obesity, while also determining whether the kombucha microbiota plays a role in the observed effects. Specifically, by investigating metabolic parameters such as glucose and insulin levels and lipid profile, as well as the composition and diversity of the gut microbiota and liver function, the study will contribute to a deeper understanding of the potential benefits and mechanisms of action of kombucha consumption in humans. The study aims to recruit at least 30 individuals with overweight and class 1 obesity, aged between 18 and 60 years, randomly distributed into 3 arms (each arm should have about 10 participants). The first arm receives a daily amount of 33 cl of kombucha (live drink) for 4 weeks, the second arm receives a daily amount of 33 cl of kombucha (pasteurized drink) for 4 weeks. The control group receives 33 cl of sparkling water for 4 weeks.

• Study Type: Interventional
• Enrollment (Estimated): 33
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Inês Brandão, PhD; Phone Number: +351926777221; Email: inesbrandao@cataa.pt
• Study Contact Backup: Name: Filomena Pereira, Nutritionist; Email: filomenapereira@cataa.pt

Study Locations

• Portugal
  • Castelo Branco, Portugal, 6000-459
    • Recruiting
    • Centro de Apoio Tecnológico Agro Alimentar (CATAA)
    • Contact: Inês Brandão, PhD; Phone Number: +351926777221; Email: inesbrandao@cataa.pt
    • Contact: Filomena Pereira, M.Sc. (Nutritionist); Phone Number: +351912069989; Email: nutricao@cataa.pt
    • Contact: Inês Brandão, PhD
  • Covilhã, Portugal, 6200-077
    • Recruiting
    • Centro de Apoio Tecnológico Agro Alimentar (CATAA) (facilities temporarily provided by the Affidea clinical analysis center)
    • Contact: Filomena Pereira, MSc (Nutritionist); Phone Number: +351912069989; Email: nutricao@cataa.pt

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Individuals with a Body Mass Index (BMI) between 25 kg/m² and 34.9 kg/m², of both biological sexes, aged between 18 and 60 years, available to comply with the study protocol (described in this document) and sign informed consent.

Exclusion Criteria:

Volunteers will be excluded from the study if they present one or more of the following conditions:

1. Subjects with sensitivity to kombucha;
2. Consumption of kombucha, kefir, kimchi, cheese, raw vinegar, sauerkraut, kvass, and other fermented products during the study and in the 3 weeks before the study.
3. Use of antibiotics in the 6 months prior to the start of the study;
4. Use of pro/prebiotics or fibers as dietary supplements or any food/molecule that modifies intestinal transit time 6 weeks before recruitment; use of laxatives 6 weeks before recruitment;
5. Specific dietary regimen (e.g., vegan); specific dietary treatment (e.g., high protein);
6. Excessive consumption of substances and alcohol; smokers;
7. Diagnosis of gastrointestinal disorders, hormonal or thyroid diseases, autoimmune diseases, and/or chronic use of corticosteroids; psychiatric disease; Type 1 or 2 diabetes;
8. Use of proton pump inhibitors; antidiabetic drugs or insulin and statins;
9. Subjects with insulin sensitivity;
10. Pregnant or lactating women;
11. Subjects with tooth sensitivity
12. Participation in another clinical trial in the last 3 months.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intervention: Kombucha (live drink); The first arm receives a daily amount of 33 cl of kombucha (live drink) for 4 weeks (dietary supplement).	Dietary supplement: Live kombucha (non filtered/ non pasteurized); Participants receive a daily amount of 33 cl of live kombucha (non-pasteurized/ non-filtered) for 4 weeks (28 days).
Experimental: Intervention: Pasteurized kombucha; The second arm receives a daily amount of 33 cl of kombucha (pasteurized drink) for 4 weeks (dietary supplement).	Dietary supplement: Pasteurized kombucha (non filtered); Participants receive a daily amount of 33 cl of kombucha (pasteurized drink) for 4 weeks (28 days).
Active Comparator: Sparkling water; The third arm receives 33 cl of sparkling water for 4 weeks (control).	Other: Control (sparkling water); Participants receive a daily amount of 33 cl of sparkling water for 4 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Gut microbiota composition and diversity (fecal samples)	Analyze the changes in the relative abundance of the microbial species present, including taxonomic identification and diversity analysis, from baseline to the end of intervention, by next-generation sequencing (NGS).	4 weeks
Change in fasting glucose levels	Fasting glucose (mg/dl), from baseline to the end of intervention. Reduction is a better outcome.	4 weeks
Change in fasting insulin levels	Fasting insulin (μUI/mL), from baseline to the end of intervention. Reduction is a better outcome.	4 weeks
Changes in Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) values	HOMA-IR values, from baseline to the end of intervention. Calculated from fasting glucose (mmol/L) X fasting insulin (mU/L) / 22.5). Less than 1.0 means insulin-sensitive, which is optimal. Above 1.9 indicates early insulin resistance. Above 2.9 indicates significant insulin resistance. Reduction is a better outcome.	4 weeks
Changes in Lipid profile	Lipid profile (total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides), in mg/dL, from baseline to the end of intervention.	4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stool consistency rating by Bristol Stool Scale	The Bristol Stool Chart is a medical tool used to classify human feces into seven distinct categories. This scale is widely regarded as the gold standard for evaluating stool consistency and intestinal transit time in adults. It ranges from type 1 (separate hard lumps), which indicates the slowest transit time and constipation, to type 7 (watery with no solid pieces), representing the fastest transit time. Daily monitoring questionnaire (to evaluate 1 to 7), from baseline to the end of intervention.	4 weeks
Variation in SIBO diagnosis (positive/negative) measured by methane and hydrogen levels in breath test	Hyrogen and methane lactulose breath test, in ppm, from baseline to end of intervention. Interpretation criteria: SIBO test is positive if there is an early increase (in the first 90 minutes) equal to or greater than 20 ppm of H2 and/or equal to or greater than 10 ppm of CH4, when compared with the lowest value obtained.	4 weeks
Change in liver enzyme levels	Analyze liver enzymes (units: in UI/L) such as alkaline phosphatase, alanine transaminase, aspartate transaminase, gamma-glutamyl transferase, from baseline to end of intervention, to determine potential hepatic effects of Kombucha consumption.	4 weeks
Change in levels of oxidative stress biomarker (ratio 8-iso-PGF2α to prostaglandin F2α (PGF2α))	Measure of oxidative stress biomarker (pg/mL ), from baseline to the end of intervention. Normal human plasma reference values: 40-100 pg/mL.	4 weeks
Change in gastrointestinal symptoms using a Likert scale	Evaluate gastrointestinal symptoms (e.g., bloating, gas) using a 10-point Likert scale, from baseline to the end of intervention. The daily questionnaire goes from zero (0) which means "no pain" to ten (10) which means "worst pain imaginable".	4 weeks
Change in high-sensitive C-reactive protein levels	Levels of h-sensitivity C-reactive protein (hsCRP), a marker of inflammation, in mg/dL, from baseline to the end of intervention. hsCRP levels of less than 0.100, 0.100 to 0.300, and greater than 0.301 mg/dL are associated with lower, moderate, and higher cardiovascular risks, respectively.	4 weeks
Change in Total oxidant capacity	Oxidative stress biomarker, pg/mL, measured from baseline to the end of intervention. Normal values range from 40-100.	4 weeks
Changes in serum albumin and bilirubin levels	Evaluate hepatobiliary function, albumin (g/dL), Bilirubin (mg/dL)	4 weeks
Changes in short chain fatty acids in stool	SCFAs in stool, units µM	4 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body weight change	Anthropometric measurement, unit of measure: Kg	4 weeks
BMI change	Body mass index (BMI) is a measure of body fat based on height and weight, unit of measure: Kg/m2	4 weeks
Waist circumference change	Anthropometric measurement, unit of measure: cm	4 weeks
Body fat percentage change	unit of measure: %	4 weeks
Changes in kidney function biomarkers- creatinin, urea and uric acid	units in mg/dL	4 weeks

Collaborators and Investigators

• Sponsor: Associação Centro de Apoio Tecnológico Agro Alimentar
• Investigators: Principal Investigator: Brandão, PhD, CATAA

Publications and helpful links

General Publications

• Moreira GV, Araujo LCC, Murata GM, Matos SL, Carvalho CRO. Kombucha tea improves glucose tolerance and reduces hepatic steatosis in obese mice. Biomed Pharmacother. 2022 Nov;155:113660. doi: 10.1016/j.biopha.2022.113660. Epub 2022 Sep 12.

Study record dates

Study Major Dates

• Study Start (Actual): October 11, 2024
• Primary Completion (Estimated): February 28, 2025
• Study Completion (Estimated): February 28, 2025

Study Registration Dates

• First Submitted: December 9, 2024
• First Submitted That Met QC Criteria: December 29, 2024
• First Posted (Actual): March 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: December 29, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Keywords: obesity; overweight; Randomized Controlled Trial; gut microbiota; liver function; metabolic parameters; Bristol Stool Form Scale; Inflammatory Biomarkers; kombucha; Small Intestinal Bacterial Overgrowth (SIBO); Nutritional Interventions; fermented beverages; fermented tea; SCOBY; live vs pasteurized kombucha; Likert Scale Analysis
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Obesity
• Other Study ID Numbers: FUSILLI: PARECER (02/2024); Grant agreement No. 101000717 (Other Grant/Funding Number: European Union's Horizon 2020 research and innovation programme)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No