Kombucha and kefir as probiotic cultures: a review
What it found
Kombucha and kefir contain probiotic bacteria and yeasts, and studies in animals and cells suggest antimicrobial, antitumour and immune effects.
Most health benefits have not been proven in human clinical studies.
What they found
Animal and lab studies
Antitumour effects in animals
In mice, kefir grain and kefir beverages reduced tumour growth. In rats, milk kefir reduced the incidence of pre-neoplastic colonic lesions by 36%.
Antimicrobial effects in lab tests
Kefir and kefiran showed activity against many pathogenic bacteria and yeasts in lab tests. Kombucha inhibited Escherichia coli, Salmonella typhi and other pathogens in lab tests.
Studies in people and animals
Immune effects in animals and cells
In mice infected with Salmonella typhi, black tea kombucha acted as an immunomodulatory agent. In human cell cultures, kombucha polysaccharides showed immunomodulatory properties.
Other findings
Database search results
Google Scholar had the most articles, about 4 million. Science Direct had about 3 million, and the BVS and Lilacs databases each had about 2 million. Nutrients and Medline had the fewest, 100 thousand or less.
Kombucha microbes and preparation
Kombucha is made by fermenting black, oolong or green tea with sugar and a symbiotic culture of bacteria and yeast called SCOBY. It ferments for 7 to 12 days at room temperature.
Kefir microbes and preparation
Kefir grains are a mix of yeasts, lactic acid bacteria and acetic acid bacteria. They can ferment milk, brown sugar, fruit juices, soy extract, vegetables and cereals, and the drink is ready after 24 to 48 hours.
What the authors conclude
“Scientific studies indicate that kefir and kombucha certainly contain various functional properties, such as antimicrobial, antitumor, anticarcinogenic and immunomodulatory activity, in addition to having a microbiological composition of probiotic bacteria and yeasts.”
Also in their conclusions
- They state that kefir and kombucha certainly contain various functional properties, such as antimicrobial, antitumor, anticarcinogenic and immunomodulatory activity.
- They note that most of the health benefits are not scientifically proven in human clinical models.
- They advise that further laboratory and clinical studies should be carried out on kefir and kombucha.
How it was done
The authors wanted to gather scientific data on the beneficial properties of probiotic kefir and kombucha, and to see how much research exists in different databases and languages.
They searched online databases up to January 2024 using keywords in English, Portuguese and Spanish, and used boxplot analysis to summarise the number of articles found. They then selected 83 articles to discuss in the review.
What it can’t tell you
- Most of the health benefits described come from animal or lab studies, so they cannot show what happens in people.
- The review did not find human clinical trials proving most of the claimed benefits.
- The search was limited to articles in English, Portuguese and Spanish, so other research may exist in other languages.
Who paid
- Conflicts
- The authors declare no conflicts of interest.
- Authors work at
- Federal University of Bahia (UFBA), Brazil; Federal University of Lavras (UFLA), Brazil; Federal University of Rio Grande (FURG), Brazil
The paper
- Title
- Biological Significance of Probiotic Microorganisms from Kefir and Kombucha: A Review
- 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
- da Anunciação TA, Guedes JDS, Tavares PPLG, et al (2024). Biological Significance of Probiotic Microorganisms from Kefir and Kombucha: A Review. Microorganisms. doi:10.3390/microorganisms12061127Free full textPubMed 38930509DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error