Green tea kombucha can transform your gut and accelerate weight loss

New research shows how green tea-based kombucha can help manage gut issues, improve metabolic health and promote healthier weight loss, offering a tasty edge to dietary interventions.

In a recent randomized controlled trial published in the journal Foods, researchers examined the effects of green tea kombucha (GTK) consumption on gut health, microbiota, and metabolism in overweight individuals on a calorie-restricted diet. They found that GTK consumption did not significantly affect microbiota composition or gut permeability, but improved gastrointestinal symptoms and altered the serum metabolome by affecting specific metabolites associated with anti-inflammatory and antioxidant properties. These results indicate potential benefits for metabolic health in overweight individuals.

Fermented foods such as kombucha have gained popularity due to their purported health benefits, including improving gut health, modulating microbiota, and combating metabolic imbalances.

Kombucha, made by fermenting sweetened green or black tea with a symbiotic culture of bacteria and yeast, contains bioactive compounds such as phenolic acids, organic acids, and vitamins. Despite its growing consumption, the true impact of kombucha on human health, especially in overweight individuals, remains unclear. Overweight individuals often have altered gut microbiota, low diversity, and a weakened gut barrier, which contributes to inflammation and metabolic disorders.

Animal studies suggest that kombucha may reduce gut dysbiosis and improve gut health. However, to date, there have been no human studies evaluating the role of GTK in combination with a calorie-restricted diet in terms of gut parameters and serum metabolomics. The present study is the first to examine the effects of GTK on GI symptoms, gut permeability, microbiota composition, and serum metabolites in overweight individuals undergoing weight loss treatment.

Overweight participants (body mass index ≥ 27 kg/m², fat mass > 30% in women and > 25% in men) were randomly assigned to two groups: a control group (CG, n = 37) receiving a calorie-restricted diet, and a kombucha group (KG, n = 38) receiving the same diet supplemented with 200 ml/day of GTK for 10 weeks. Exclusion criteria included the presence of metabolic or chronic diseases, regular use of supplements or fermented foods or teas. GTK was produced in a laboratory setting, with probiotics at 1 billion colony-forming units per serving.

Participants maintained their usual levels of physical activity and dietary habits, which were monitored throughout the study. Outcomes, quality of life, and gastrointestinal symptoms were assessed using questionnaires, anthropometry, biological sample collection, and metabolic testing.

Microbiota analysis was performed to assess diversity, taxon trends such as increased Romboutsia and decreased Alistipes, and correlations with metabolites in the GTK group. The metabolome was studied using serum samples.

Both the KG and CG groups experienced weight loss and improved body composition, although there were no significant differences between them. The KG group also experienced a small increase in daily fiber intake, but this was not statistically significant.

Gut Microbiota Trends

Although GTK did not significantly alter the microbiota composition, trends toward an increase in beneficial Romboutsia bacteria and a decrease in potentially harmful Alistipes were observed, indicating a subtle modulation of the microbiota.

In terms of quality of life, the CG group improved in total scores, physical function, and body pain, while the KG group improved in total scores, general health, vitality, and emotional role, but there was no significant difference between the groups.

Gut parameters including zonulin (a biomarker of intestinal barrier dysfunction), lipopolysaccharide-binding protein, short-chain fatty acids (SCFAs) and stool pH showed no significant differences between groups after the intervention, except for the CG group, which showed an increase in lactulose/mannitol ratio, stool pH and zonulin levels. Both groups showed a decrease in butyric acid production, but there were no other significant changes in SCFAs.

GI symptoms improved in both groups, but KG showed greater improvements, particularly in symptoms such as hard stools and incomplete bowel movements. The KG group also showed significant changes in stool consistency, with an increase in type 4 stools.

Additionally, there were no significant differences between groups at the genus level, although KG showed a decrease in Alistipes and an increase in Romboutsia. Alpha diversity increased in both groups, with a higher Chao 1 index in the KG group at the genus level compared to baseline.

In conclusion, serum metabolomics identified 25 putative metabolites in the KG group, predominantly related to amino acid and fatty acid metabolism, including diethyl malonate and taurine, with correlations between microbiota changes and metabolites.

The study’s rigorous design enhances its power, but the relatively small sample size and limited number of biological samples limit the results. The use of laboratory-made GTK, although standardized, may differ from commercial versions, which may affect the generalizability of the results.

In conclusion, the study showed that GTK improved GI symptoms, especially promoting complete bowel movement and facilitating firm stools in overweight individuals undergoing weight loss treatment. Although no significant modulation of gut microbiota was observed, trends toward increased diversity and changes in certain taxa were identified, which warrant further investigation in future trials. The CG group showed worsening of intestinal permeability and stool pH, suggesting that kombucha may help prevent these negative effects.

Additionally, kombucha consumption influenced the serum metabolome, with metabolites linked to metabolic, anti-obesity, anti-inflammatory, and antioxidant pathways, potentially improving overall health in overweight individuals.