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

Official title

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]

Overview

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.

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.

Interventions

• 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).
• Dietary supplement Pasteurized kombucha (non filtered)
  Participants receive a daily amount of 33 cl of kombucha (pasteurized drink) for 4 weeks (28 days).
• Other Control (sparkling water)
  Participants receive a daily amount of 33 cl of sparkling water for 4 weeks.

Primary outcome measures

• Change in Gut microbiota composition and diversity (fecal samples) [Time frame: 4 weeks]
• Change in fasting glucose levels [Time frame: 4 weeks]
• Change in fasting insulin levels [Time frame: 4 weeks]
• Changes in Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) values [Time frame: 4 weeks]
• Changes in Lipid profile [Time frame: 4 weeks]

Secondary outcome measures (9)

• Stool consistency rating by Bristol Stool Scale [Time frame: 4 weeks]
• Variation in SIBO diagnosis (positive/negative) measured by methane and hydrogen levels in breath test [Time frame: 4 weeks]
• Change in liver enzyme levels [Time frame: 4 weeks]
• Change in levels of oxidative stress biomarker (ratio 8-iso-PGF2α to prostaglandin F2α (PGF2α)) [Time frame: 4 weeks]
• Change in gastrointestinal symptoms using a Likert scale [Time frame: 4 weeks]
• Change in high-sensitive C-reactive protein levels [Time frame: 4 weeks]
• Change in Total oxidant capacity [Time frame: 4 weeks]
• Changes in serum albumin and bilirubin levels [Time frame: 4 weeks]
• Changes in short chain fatty acids in stool [Time frame: 4 weeks]

Eligibility criteria

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:

• Subjects with sensitivity to kombucha;
• 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.
• Use of antibiotics in the 6 months prior to the start of the study;
• 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;
• Specific dietary regimen (e.g., vegan); specific dietary treatment (e.g., high protein);
• Excessive consumption of substances and alcohol; smokers;
• Diagnosis of gastrointestinal disorders, hormonal or thyroid diseases, autoimmune diseases, and/or chronic use of corticosteroids; psychiatric disease; Type 1 or 2 diabetes;
• Use of proton pump inhibitors; antidiabetic drugs or insulin and statins;
• Subjects with insulin sensitivity;
• Pregnant or lactating women;
• Subjects with tooth sensitivity
• Participation in another clinical trial in the last 3 months.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Triple blind

Primary purpose

Other

Study locations

Portugal · 2 centers

• Centro de Apoio Tecnológico Agro Alimentar (CATAA) — Castelo Branco
• Centro de Apoio Tecnológico Agro Alimentar (CATAA) (facilities temporarily provided by the — Covilha

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. PMID 36095960

Identifiers

NCT: NCT06759324 · FUSILLI: PARECER (02/2024) · Grant agreement No. 101000717

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗