Regular Consumption of Black Tea Kombucha Modulates the Gut Microbiota in Individuals with and Without Obesity

Background: Kombucha, a fermented beverage obtained from a Symbiotic Culture of Bacteria and Yeast (SCOBY), has shown potential in modulating gut microbiota, although no clinical trials have been done.

Objective: We aimed to evaluate the effects of regular black tea kombucha consumption on intestinal health in individuals with and without obesity.

Methods: A pre-post clinical intervention study was conducted lasting eight weeks. Forty-six participants were allocated into two groups: normal weight + black tea kombucha (n=23); and obese + black tea kombucha (n=23). Blood, urine, and stool samples were collected at baseline (T0) and after 8 weeks of intervention (T8).

Results: A total of 145 phenolic compounds were identified in the kombucha, primarily flavonoids (81%) and phenolic acids (19%). Kombucha favored commensal bacteria such as Bacteroidota and Akkermanciaceae, especially in the obese group. Subdoligranulum, a butyrate producer, also increased in the obese group after kombucha consumption (p=0.031). Obesity-associated genera Ruminococcus and Dorea were elevated in the obese group at baseline (p<0.05) and reduced after kombucha consumption, becoming similar to the normal weight group (Ruminococcus: obese T8 x normal weight T8: p=0.27; Dorea: obese T8 x normal weight T0: p=0.57; obese T8 x normal weight T8: p=0.32). Fungal diversity increased, with a greater abundance of Saccharomyces in both groups and reductions in Exophiala and Rhodotorula, particularly in the obese group. Pichia and Dekkera, key microorganisms in kombucha, were identified as biomarkers after the intervention.

Conclusions: Regular kombucha consumption positively influenced gut microbiota in both normal and obese groups, with more pronounced effects in the obese group, suggesting that it may be especially beneficial for those individuals.

Registration id and url: This study is registered on the Brazilian Clinical Trial Registry - ReBEC (UTN code U1111-1263-9550); available at <https://ensaiosclinicos.gov.br/rg/RBR-9832wsx>.

Clinical trial statement: This study was conducted according to the guidelines established in the Declaration of Helsinki and the procedures were approved by the National Research Ethics Committee - CONEP/Brazil (registration no. 3.948.033). Written informed consent was obtained from all subjects. This study is registered on the Brazilian Clinical Trial Registry (ReBEC), available at <https://ensaiosclinicos.gov.br/rg/RBR-9832wsx> (UTN code U1111-1263-9550).