Kombucha tea as a functional beverage and its health effects
What it found
Kombucha contains organic acids, antioxidants and probiotics that may support digestion, immunity and blood sugar control.
Most studies were done in lab tests or animals, with only a few in people.
What they found
Animal and lab studies
Antioxidant effects
Kombucha contains polyphenols and glucuronic acid, which can neutralise free radicals. In one study, antioxidant activity peaked on day 7 at 93.8% and then fell slightly to 93.6% by day 11.
Antimicrobial effects
In lab tests, kombucha inhibited several harmful bacteria including E. coli, Salmonella Typhi, Shigella dysenteriae and Vibrio cholerae. The antimicrobial activity was linked to its acetic acid content.
Anticancer effects
Lab studies found kombucha had toxic effects on liver cancer cells and slowed the growth of prostate cancer cells. These effects have mainly been seen in lab tests, not in people.
Studies in people and animals
Blood sugar effects
In a mouse study, kombucha improved blood sugar control by balancing gut bacteria. A small pilot study in people with type 2 diabetes also found a possible drop in blood sugar.
Heart effects
A study in rabbits found kombucha may help prevent problems from a high-cholesterol diet. A case report described a woman who died after drinking homemade kombucha, though this is a single case.
Probiotic effects
Kombucha is thought to support gut health by encouraging beneficial bacteria like Lactobacillus and Bifidobacterium. However, some studies found no changes in gut bacteria after taking kombucha.
Other findings
Fermentation and composition
Kombucha is made by fermenting sweetened tea with a symbiotic culture of bacteria and yeast, usually for up to 14 days. This turns sugar into ethanol and acetic acid, giving the drink its tangy taste.
What the authors conclude
“While some studies have highlighted its antioxidant, antimicrobial, and probiotic effects, others suggest that prolonged fermentation or specific compositions may reduce its efficacy.”
Also in their conclusions
- They say kombucha could be used as a supportive measure in the prevention and treatment of many diseases, but inconsistencies in the literature remain.
- They call for further standardized and controlled studies to clarify conflicting findings and establish clear guidelines for kombucha consumption.
- They advise that randomized controlled human studies using more standardized products and protocols are essential to obtain accurate and generalizable results.
How it was done
The authors wanted to review the definition, bioactive components and health benefits of kombucha, and its potential role in preventing and managing diseases.
They reviewed the scientific literature on kombucha's history, production, bioactive components and health effects, including studies in lab tests, animals and a small number of people.
What it can’t tell you
- Most studies were done in lab tests or animals, so it is unclear whether the results apply to people.
- The lack of standardization in kombucha preparation makes it hard to determine its health effects.
- Some studies show benefits while others show none, so the overall picture is conflicting.
Who paid
- Conflicts
- Declarations. Conflict interest: The authors declare no competing interests. Human and Animal Rights and Informed Consent: This article does not contain any studies with human or animal subjects performed by any of the authors.
- Authors work at
- Ankara Medipol University, Turkey
The paper
- Title
- Kombucha Tea: A Functional Beverage and All its Aspects
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Onsun B, Toprak K, Sanlier N (2025). Kombucha Tea: A Functional Beverage and All its Aspects. Current nutrition reports. doi:10.1007/s13668-025-00658-9Free full textPubMed 40411688DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error