Kombucha is one of the most intensively studied fermented beverages in recent years. Modern microbiological, nutritional, and clinical studies show that the beverage has an exceptionally complex biochemical composition. During fermentation, numerous bioactive compounds are formed, including organic acids, polyphenols, enzymes, vitamins, and various microorganisms.
Current scientific literature highlights several key effects and properties of kombucha:
- a high diversity of microorganisms, including bacteria and yeasts
- the formation of numerous bioactive metabolic products during fermentation
- a high content of antioxidant polyphenols
- a potential modulation of the gut microbiome
- metabolic effects related to lipid metabolism and metabolic parameters
- a role of fermented acids in digestive processes and microbial balance
These properties make kombucha, from a scientific perspective, a particularly complex functional fermented food.
Fermentation: The Biochemical Origin of its Effects
Kombucha is produced by fermenting sweetened tea with a so-called SCOBY culture (Symbiotic Culture of Bacteria and Yeast). This symbiotic community of bacteria and yeasts produces a variety of bioactive metabolites during fermentation.
A comprehensive review describes kombucha as a dynamic microbial ecosystem where yeasts convert sugar into ethanol and carbon dioxide, while acetic acid bacteria further metabolize this alcohol into organic acids (Jayabalan et al., 2014).
Key substances formed during fermentation include:
- acetic acid
- gluconic acid
- glucuronic acid
- lactic acid
- polyphenol metabolites
- bacterial enzymes
This biochemical transformation results in kombucha having a significantly different composition than the original tea.
Recent microbiological analyses show that kombucha can contain more than 200 different microbial species from over 30 genera (Nutritional Metagenomics Analysis, 2021). Particularly dominant are acetic acid bacteria such as Acetobacter and Komagataeibacter, which are responsible for the production of organic acids.
Polyphenols and Antioxidant Effects
An important part of scientific research on kombucha concerns its antioxidant properties.
Tea – the basis of kombucha – already contains a high concentration of polyphenols, especially catechins, flavonoids, and phenolic acids. During fermentation, these compounds are partially converted enzymatically, thereby becoming more bioavailable.
A comprehensive analysis of its ingredients describes kombucha as rich in antioxidant compounds that are formed or enhanced during fermentation (Martínez Leal et al., 2018).
Polyphenols are of particular scientific interest because they can:
- reduce oxidative stress
- interact with metabolic processes
- influence microbial growth in the gut
In a clinical study involving regular kombucha consumption, 145 different phenolic compounds were identified in the beverage, including flavonoids and phenolic acids (Costa et al., 2025).
These compounds play an important role in antioxidant protective mechanisms in the body.
The Microbiological Diversity of Kombucha
The microbiological composition of kombucha is one of the most important factors for its properties.
A genetic analysis of several kombucha samples showed that the beverage contains a stable community of bacteria and yeasts (Marsh et al., 2014). The most common microorganisms include:
Bacteria
- Komagataeibacter
- Acetobacter
- Gluconobacter
- Lactobacillus
Yeasts
- Saccharomyces
- Brettanomyces
- Zygosaccharomyces
- Pichia
These microorganisms form complex metabolic networks during fermentation and produce numerous bioactive metabolites.
Microbiological diversity is considered one of the reasons why kombucha is frequently studied in scientific research in connection with the gut microbiome.
Impact on the Gut Microbiome
The gut microbiome is one of the central research topics in modern nutritional science. Fermented foods are a particular focus.
A controlled clinical study from 2024 investigated the effects of kombucha consumption on the gut microbiome of adults. The analysis was based on high-resolution shotgun sequencing of stool samples (Ecklu-Mensah et al., 2024).
The results showed:
- changes in the composition of the gut microbiota
- an increased presence of certain microbial species from fermented foods
- adaptations in microbial metabolic pathways
Among other findings, an increased relative abundance of Weizmannia coagulans and changes in metabolic pathways for vitamin and nucleotide biosynthesis were observed.
Further studies confirm these effects.
An intervention study with regular kombucha consumption showed changes in the gut flora, including:
- an increase in Bacteroidota
- an increased presence of Akkermansiaceae
- an increase in Subdoligranulum, a known butyrate-producing gut bacterium (Costa et al., 2025).
Butyrate is one of the most important short-chain fatty acids in the gut and plays a significant role in gut health.
Another clinical study also showed that kombucha can increase the proportion of Bifidobacterium, a bacterial genus strongly associated with gut health and immunological processes.
Effects on Digestion and Gut Function
Several clinical investigations report on the effects of kombucha on digestive function.
A systematic analysis of clinical studies found that kombucha consumption was associated with improvements in certain gastrointestinal symptoms, including:
- improved stool consistency
- reduced discomfort with incomplete bowel evacuation
- improved gut motility
Researchers attribute these effects to the organic acids contained in the beverage.
Organic acids such as acetic acid, citric acid, or malic acid can influence physiological processes in the gut. Studies show that these acids can increase gut motility by stimulating the production of prostaglandin E₂, which binds to receptors on smooth intestinal muscles and supports peristaltic movements.
Influence on Metabolism and Metabolic Parameters
Another area of research concerns possible metabolic effects of kombucha.
A randomized intervention study with 60 participants investigated the effects of daily kombucha consumption over six weeks. Both metabolic parameters and changes in the gut microbiome were analyzed.
The results showed:
- changes in lipid metabolism
- a reduction in triglyceride levels
- changes in the gut microbiota favoring certain bacterial groups
In parallel, a systematic review on kombucha and metabolic health showed that the beverage is associated with a reduction in oxidative stress, an improvement in metabolic processes, and a reduction in intestinal dysbiosis.
Antimicrobial Properties
In addition to the microbial effects on the gut microbiome, antimicrobial activity is also being investigated in certain kombucha samples under laboratory conditions.
These are primarily caused by several factors:
- acetic acid
- gluconic acid
- low pH value
- phenolic compounds
Laboratory studies show that kombucha can have inhibitory effects against various pathogenic microorganisms. These properties are often attributed to the combination of organic acids and phenolic plant compounds.
Vitamins and Minerals
In addition to the metabolites produced during fermentation, kombucha also contains various micronutrients.
An analysis of its nutritional content showed the presence of several water-soluble vitamins and minerals in the beverage (Bauer & Petrusevska-Tozi, 2001).
These include:
- B vitamins
- Vitamin C
- Potassium
- Magnesium
- Iron
These micronutrients partly originate from the tea and are partly formed during fermentation.
Kombucha as a Complex Functional Food
Modern scientific reviews increasingly describe kombucha as a functional fermented beverage, whose properties arise from the interplay of several factors:
- Fermentation of tea
- Microbial ecosystem of bacteria and yeasts
- Formation of organic acids
- High concentration of plant polyphenols
- Production of microbial metabolites
This combination leads to an exceptionally complex biochemical structure that is increasingly being investigated in nutritional science.
A current review therefore describes kombucha as a beverage with "therapeutic potential due to its microbial diversity, bioactive metabolites, and antioxidant properties" (Prajapati et al., 2024).
Kombucha and Holistic Well-being
In addition to its biochemical properties, researchers are also investigating kombucha's role in the context of holistic nutrition.
A recent scientific analysis describes kombucha as a functional fermented beverage that, due to its microbial diversity, antioxidant compounds, and fermentation products, is associated with various aspects of physical and mental health (Batista et al., 2023).
The following areas, among others, are discussed:
- metabolic processes
- oxidative stress
- gut microbiome
- general well-being
Popular science summaries of studies also highlight that kombucha contains a variety of bioactive ingredients that are created through fermentation (Leech, 2023; Herzig, 2025).
Conclusion: Kombucha – A Versatile Fermented Beverage in the Focus of Research
Scientific research shows that kombucha can have a complex composition. During the fermentation of tea, various microorganisms, organic acids, polyphenols, and other fermentation products may be present. The specific substances contained and their quantities depend on the recipe, culture, and manufacturing process.
The microbial composition and the metabolic products formed during fermentation are particularly subjects of current research. Possible connections with the gut microbiome, various metabolic parameters, and digestive processes are among the topics being investigated.
The results obtained so far come from different study models, recipes, manufacturing processes, and groups of people. Therefore, they do not allow for a blanket statement about the health benefits of kombucha or the effect of a specific kombucha product.
Kombucha is thus primarily a scientifically interesting fermented tea beverage, whose complex composition and fermentation processes continue to be subjects of research.
Study Overview
Kombucha: Refreshing and Healing Through Fermentation
Herzig, K. (2025). Kombucha: Refreshing and Healing Through Fermentation. G. Dorschner (Prüf.). The full article can be found here.
7 Evidence-Based Health Benefits of Kombucha
Leech, J. (2023). 7 Evidence-Based Health Benefits of Kombucha. Healthline. The full article can be found here.
The Health Benefits of Kombucha's Nutritional Compounds and Metabolites
Martinez Leala, J., Valenzuela Suárez, L., Jayabalan, R., Huerta Oros, J., & Escalante-Aburto, A. (2018). A review on health benefits of kombucha nutritional compounds and metabolites. CyTA - Journal of Food, 16(1), 390-399. The full article can be found here.
Minerals and Vitamins in Kombucha
Bauer, B., & Petrusevska Tozi, L. (2001). Mineral and water soluble vitamin content in the Kombucha drink. International Journal of Food Science & Technology, 35(2), 201-205. The full article can be found here.
A Review on Kombucha – Microbiology, Composition, Fermentation & Health Benefits
Jayabalan, R., Malba, R. V., Lonar, E. S., Vitas, J. S., & Sathishkumar, M. (2014). A review on Kombucha tea—Microbiology, composition, fermentation, beneficial effects, toxicity, and tea fungus. Comprehensive Reviews in Food Science and Food Safety, 13(4), 538-550. The full article can be found here.
Impact of Kombucha on the Human Gut Microbiome and Key Health Indicators
Ecklu-Mensah, G., Miller, R., Maseng, M. G., Hawes, V., Hinz, D., Kim, C., & Gilbert, J. A. (2024). Modulating the human gut microbiome and health markers through kombucha consumption: A controlled clinical study. Scientific Reports, 14(1), 31647. The full article can be found here.
Microbiological Study of Kombucha Alchemy: Analysis of Bacterial Compositions
Marsh, A. J., O'Sullivan, O., Hill, C., Ross, R. P., & Cotter, P. D. (2014). Sequence-based analysis of the bacterial and fungal compositions of multiple kombucha (tea fungus) samples. Food Microbiology, 38, 171-178. The full article can be found here.
The Effect of Kombucha on Physical and Mental Health
Batista, P., Rodrigues Penas, M., Vila-Real, C., Pintado, M., & Oliveira-Silva, P. (2023). Kombucha: Challenges for health and mental health. Foods (Basel, Switzerland), 12(18), 3378. The full article can be found here.
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