Kombucha can rebalance gut ecosystem in people with obesity: study

The Hindu

a day ago

From Instagram reels to supermarket shelves, kombucha — the fizzy, fermented tea drink — has found a growing audience among health-conscious consumers in India. Promoted as a probiotic powerhouse, it's touted for its supposed benefits to digestion, immunity, and metabolism. According to one estimate provided by Indian company Sbooch, the kombucha market in India grew from $45 million in 2020 to $102 million in 2024.
Yet much of the enthusiasm has outpaced science. While kombucha's traditional use and composition suggest potential health benefits, few rigorous studies have tested these claims in humans. Most research until now has focused on kombucha's biochemistry or has been limited to animal models.
This is why a recent study in The Journal of Nutrition stands out: it takes a closer look at kombucha's effects on the human gut microbiome and how they matter for human health.
The study followed 46 healthy adults in Brazil — 23 with obesity and 23 of normal weight — over eight weeks in a pre-post trial. The participants were classified using (World Health Organisation cut-offs of) BMI and waist circumference. Every day, each participant consumed 200 ml of kombucha that had been prepared in the lab using black tea and fermented with a symbiotic culture of bacteria and yeast (SCOBY).
All participants were otherwise healthy and had no recent history of drugs, antibiotics or supplements. Stool samples were collected at the beginning and end to assess gut microbiome changes. The researchers used genomic tools to profile bacterial and fungal communities.
They also measured fasting blood glucose, insulin, and proteins linked to gut barrier integrity since a weakened gut lining can allow harmful molecules to enter the bloodstream, trigger low-grade inflammation, and ultimately engender insulin resistance.
What we know, what changed
After eight weeks, the overall microbial diversity was largely unchanged but the abundance of certain bacteria had changed in ways that suggested kombucha may help positively rebalance the gut ecosystem.
Notably, the population of Akkermansiaceae bacteria had increased in individuals with obesity. Previous research has linked this shift with better blood sugar control and insulin sensitivity.
The levels of Prevotellaceae also increased, specifically in the obese group. Certain strains of Prevotella copri have similarly been linked to improved insulin sensitivity, hypertension, and inflammation. Both groups also reported higher abundance of Bacteroidota, which play significant roles in digesting complex carbohydrates.
Bacteria associated with less favourable outcomes including Ruminococcus and Dorea declined, becoming similar to the normal-weight group by the eighth week. Ruminococcus gnavus has been positively associated with inflammatory bowel disease and liver fat accumulation, while Dorea with high BMI and cholesterol markers.
In normal-weight participants, Parabacteroides increased modestly. Parabacteroides goldsteinii has been known to reduce tissue inflammation, ameliorating chronic obstructive pulmonary disease and Helicobacter pylori infections.
The populations of Exophiala and Rhodotorula, two fungi associated with cystic fibrosis and obesity respectively, decreased as well.
While the study offers promising clues about kombucha's influence, especially for individuals with obesity, the researchers urged caution. The microbial shifts were modest and didn't improve metabolic markers like blood glucose, insulin, or inflammatory proteins. The team also pointed out that microbial responses vary by diet, genetics, and overall health, thus reducing the generalisability of the findings. And with a short duration and a modest sample size, the findings remain a proof-of-concept.
The results are still valuable in what they reveal, however: kombucha does appear to nudge the gut microbiome in directions associated with better metabolic health after two months.
Kombucha and India
Whether the effects will hold for Indian populations remains an open question. Studies have indicated gut microbiota in India are unique. Indian guts, particularly among those consuming traditional plant-based diets, harbour more Prevotella, an inversion of the typical Western microbial pattern. Since consuming kombucha increased Prevotellaceae abundance in the study, it may not drive the same degree of change in local populations.
Even within India, while North Indians have more Prevotella, South Indians carry a higher load of Bacteroides and Ruminococcus. Women from rural high-altitude areas have greater gut diversity than their urban counterparts. Ethnic tribes from Ladakh, Jaisalmer, and Khargone can be differentiated based on their gut microbiomes alone.
Taken together, the new study is proof that no single brand of kombucha can claim to be 'good' for all consumers across geographies. The drink may support gut health but whether that translates to long-term metabolic benefits remains to be seen.
Anirban Mukhopadhyay is a geneticist by training and science communicator from Delhi.