In our intestines, a silent war is being fought between good and bad bacteria, and for years we thought that the only way to win it was to radically change our diet and lifestyle. Then came this study from the University of Viçosa, in Brazil, that turned everything upside down. 38 volunteers drank kombucha for two months without changing anything else.
The result? Their “obese” microbiotas became indistinguishable from those of normal-weight people. A transformation that surprised even the researchers who observed it. Let's take a look.
How Kombucha Convinces Bacteria to Behave
A systematic review, Published on The Journal of Nutrition, followed a rigorous but surprisingly simple protocol. Researchers divided participants into two groups: 21 normal-weight people and 17 obese people. The only change to their daily routine? A 200-milliliter glass of black tea kombucha every day for eight straight weeks.
Josefina Bressan and his team at the Federal University of Viçosa did not expect such clear results. “It is the first time that a clinical trial has demonstrated how regular consumption of kombucha can significantly modulate the human microbiota,” the researchers explain. But the real surprise came when they analyzed the fecal samples: the most profound changes occurred precisely in the obese group.
Kombucha acted as a sort of “diplomatic mediator” in the intestinal chaos. The levels of Akkermansia muciniphila, a crucial bacterium for reducing inflammation and improving insulin sensitivity, have increased dramatically. This small organism strengthens the intestinal barrier, that “wall” that when compromised can trigger chronic inflammatory diseases.
Obesity bacteria lose ground
But there’s more. Kombucha has shown an almost surgical ability to “disarm” obesity-associated bacteria. Ruminococcus e wanted, two bacterial genera that thrive in obese guts and fuel inflammation and visceral fat accumulation, have seen their populations significantly decline.
“It’s as if kombucha had rewritten the gut ecosystem,” the research team explains.
After eight weeks, the bacterial profiles of the obese participants were much more similar to those of the normal-weight group, a change that would normally require months of strict dieting and major lifestyle changes.
The analysis revealed 145 phenolic compounds in kombucha, mainly flavonoids (81%) and phenolic acids (19%). These compounds act as a “selective fertilizer”, preferentially feeding beneficial bacteria while creating a hostile environment for pathogenic ones.
Kombucha, the secret is in the fermentation
Not all kombucha is created equal, though. The researchers used a version made according to the traditional recipe: black tea, sugar, and a symbiotic culture of bacteria and yeast (SCOBY) left to ferment for a week. This fermentation produces organic acids that lower the pH of the intestines, creating ideal conditions for beneficial bacteria.
As I explained in this article, personalized probiotic research is making great strides. But this study on scoby Kombucha shows that sophisticated approaches aren’t always necessary: sometimes a fermented beverage consumed consistently is enough.
Implications beyond the gut
The researchers also observed changes in the mycobiota, the ecosystem of intestinal fungi. Problematic fungi such as Rhodotorula, Exophiala e Candida, often associated with obesity and intestinal inflammation, have seen their presence reduced. In their place, beneficial fungi such as saccharomyces.
“We’re not just talking about adding good bacteria,” the researchers point out. “Kombucha creates an environment that promotes balance throughout the gut microbial ecosystem.” This “ecological” approach could explain why the results were so pronounced in the obese group: quite simply, an unbalanced microbiota has more room for improvement.
The Road to Personalized Medicine
This study opens up exciting possibilities for the future of preventive medicine. If a simple fermented beverage can produce such profound changes without requiring drastic lifestyle changes, imagine the possibilities when we have truly personalized probiotics.
The main limitation of the study? The lack of a control group that did not drink kombucha. The researchers compared only normal-weight and obese people, both of whom consumed the beverage. A control group would have given even more strength to the data, but the robustness of the observed changes and their specificity still make the results very convincing.
A fermented future
For now, the food industry has taken note. The Kombucha Market is growing rapidly, with estimates of $5 billion by the end of 2025. But be careful: not everything that goes by the name of kombucha has the same probiotic properties. Pasteurization, often used to extend shelf life, eliminates the living microorganisms that make this drink special.
The final message is simple: our intestine is a complex ecosystem that can be positively influenced by targeted food choices. Drastic revolutions are not always necessary. Sometimes it is enough to listen to what thousands of years of fermentation traditions tell us, which are now finally being validated by modern science.
