Kombucha, gut bacteria and health markers in a controlled trial
What it found
In 24 healthy adults on a Western diet, four weeks of daily kombucha did not change most blood or inflammation markers, but it did slightly shift gut bacteria and was linked to small rises in fasting insulin and insulin resistance within the kombucha group.
What they found
Studies in people
Blood markers overall
There were no significant changes in diastolic blood pressure, systolic blood pressure, fasting glucose, triglycerides, HDL cholesterol, or waist circumference between the kombucha and control groups over time. Fasting insulin and LDL cholesterol also did not differ between groups.
Within-group changes
Within the kombucha group, fasting insulin and HOMA-IR increased significantly from baseline to end of intervention. In the control group, HDL cholesterol decreased significantly and creatinine increased marginally.
Inflammation markers
No significant changes in the inflammation markers IL10, IL6 and CRP were seen within either group or between groups at the end of the intervention.
Gut bacteria composition
Overall microbial diversity did not differ between kombucha consumers and controls, but the composition of gut bacteria differed significantly between groups. Within the kombucha group, diversity decreased modestly from baseline to end of intervention.
Specific bacteria enriched
The kombucha group had higher levels of Weizmannia coagulans, a bacterium found in the kombucha product, and several short-chain fatty acid producing taxa including Prevotella and Bifidobacterium species. Some bacteria such as Parabacteroides and Lactobacillus were depleted.
Gastrointestinal discomfort
Diarrhea and bloating were reported by 31.25% of the kombucha group compared with 12.5% of the control group. Abdominal pain was reported by 25% of the control group and about 12.5% of the kombucha group.
What the authors conclude
“Collectively, in our healthy cohort consuming a Western diet, a short-term kombucha intervention induced modest impacts on human gut microbiome composition and biochemical parameters, which may be attributed to relatively small number of participants and the extensive inter-participant variability.”
Also in their conclusions
- They conclude that a short-term kombucha dietary intervention in healthy participants differentially influenced the composition of gut microbiota, enriching several SCFA producing taxa.
- They state that these compositional changes did not correspond to broad shifts in biochemical or inflammation profiles, at least over this short-term intervention.
- They advise that applying multi-omic approaches on larger sample size with longer study duration are needed to delineate the impact of kombucha consumption on gut microbiota modulation and its connection to human health and disease outcomes.
How it was done
Fermented foods are popular for claimed metabolic and gut health benefits, but direct clinical evidence in people is lacking. The authors wanted to test kombucha's effects on the gut microbiome and health markers in a controlled human study.
They ran an eight-week randomised controlled trial in 30 healthy adults on a Western diet, assigned 2:1 to kombucha or control. After exclusions, 24 people (16 kombucha, 8 control) completed the study; the kombucha group drank 16 oz of commercial kombucha daily for four weeks. Stool and blood samples were collected at three time points to measure gut bacteria, metabolic markers and inflammation.
What it can’t tell you
- The study was small and short, so it cannot show whether longer or larger use of kombucha would have different effects.
- The participants were healthy adults on a Western diet, so the results may not apply to other groups or diets.
- The study cannot show whether the small changes in gut bacteria cause any health effects.
Who paid
- Funding
- Funded by NIH HHS (from the PubMed record).
- Conflicts
- Competing interests: Funding for this study was supported by GT’s living foods LLC. Jack A. Gilbert was on the scientific advisory board for GT’s living foods. All other authors declare no competing interests. GT was not involved in the analysis or presentation of the study data. The views expressed in this research article are those of the authors and do not necessarily reflect the position or policy of GT’s living foods.
- Authors work at
- University of California San Diego, USA; University of Oslo, Norway; Oslo University Hospital, Norway
The paper
- Title
- Modulating the human gut microbiome and health markers through kombucha consumption: a controlled clinical study
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Ecklu-Mensah G, Miller R, Maseng MG, et al (2024). Modulating the human gut microbiome and health markers through kombucha consumption: a controlled clinical study. Scientific reports. doi:10.1038/s41598-024-80281-wFree full textPubMed 39738315DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error