Writing in Scientific Reports, scientists from the University of California San Diego and the La Jolla Institute for Immunology reported that kombucha consumption led to increases in one population, Weizmannia coagulans, as well as several short-chain fatty acid-producing taxa. However, a “minimal” decrease in overall microbiota diversity was also reported.
“The dominance of Weizmannia coagulans in the kombucha consumers indicates that within four weeks of kombucha administration, the gut microbiome composition is characterized by an increase in bacteria ingested from the product,” the researchers wrote.
“Our finding aligns with a prior study on the kombucha microbiota that identified Weizmannia as the most abundant bacterium present in the specific kombucha brand used in our study.”
Study details
Data from animal studies have suggested that consumption of the fermented food kombucha is associated with a range of potential health benefits, including blood sugar control, antioxidant and anti-inflammatory effects, and gut microbiota changes linked to improved metabolic health, the researchers noted.
Twenty-four participants were recruited to participate in the parallel, randomized clinical controlled trial, with 16 people assigned to the kombucha group and eight to the control group. Both groups maintained a “beige” low-fiber diet for eight weeks. For the final four weeks of the study, the kombucha group consumed 16 ounces per day of a commercially available kombucha.
The product used in the study was formulated with Weizmannia coagulans GBI-306086 (formerly known as Bacillus coagulans). This is a non-pathogenic lactic acid‐producing spore‐forming bacterium that is extensively used in food and beverage products because of its tolerance to high temperature and food processing techniques.
Before, during and after supplementation, fasting bloodwork, anthropometrics data, stool samples, questionnaires and food records were collected.
Microbiota changes
The kombucha group had an increase in relative abundance of Weizmannia coagulans, as well as several SCFA-producing taxa.
“Certain strains of Weizmannia coagulans can restructure the gut microbiota by increasing the abundance of intestinal transforming ellagic acid bacteria such as Ellagibacter isourolithinifaciens to facilitate the bioavailability of polyphenols,” the researchers wrote.
“In our study, we detected proportional increases of Ellagibacter isourolithinifaciens, after four weeks of kombucha consumption, known to be involved in dietary polyphenol metabolism in healthy individuals.”
Overall, there was a minimal decrease in microbiota diversity for the kombucha group.
Other results
The study also analyzed longitudinal stool and blood sample data for any changes in inflammation markers or biochemical parameters but found none.
Participants reported diarrhea and bloating more frequently than the control group, though abdominal pain was higher for the control group.
The paired analysis showed increases in HOMA-IR, which can estimate insulin resistance, and fasting insulin for the kombucha group.
Some of the study’s results contrast with prior research, specifically the decrease in microbiota diversity.
The researchers suggested that this could be attributed to the small sample size, short duration or other factors, such as the “beige” Western diet that may affect kombucha’s ability to impact microbial diversity.
“A short-term kombucha dietary intervention in healthy participants differentially influenced the composition of gut microbiota, enriching several SCFA producing taxa,” they concluded.
“However, these compositional changes did not correspond to broad shifts in biochemical or inflammation profiles, at least over this short-term intervention. 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.”
Source: Scientific Reports, 30(14):31647. doi: 10.1038/s41598-024-80281-w. “Modulating the human gut microbiome and health markers through kombucha consumption: a controlled clinical study”. Authors: G. Ecklu-Mensah, et al.