Kombucha: Concept and health benefits

Origins

Kombucha, a tangy and refreshing fermented tea, has become increasingly popular for its potential health benefits. Originating in ancient China, this probiotic-rich drink spread to Japan, Russia, and Eastern Europe before making its way to the West, where it's now celebrated for its unique taste and wellness properties.

Crafted by fermenting sweetened tea with a SCOBY (Symbiotic Culture of Bacteria and Yeast), a gallon of kombucha typically ferments for 7 to 21 days. The SCOBY consumes the sugar during this process, producing beneficial compounds like polyphenols, B vitamins, and essential minerals. While a longer fermentation increases these health-promoting compounds, it also raises organic acid levels, which can make the drink too sour. Thus, sticking to recommended fermentation times is key for safety and taste.

Probiotic power

The probiotics in kombucha, such as Lactobacillus, Bifidobacterium, Bacillus cereus, Propionibacterium freudenreichii, and various yeast species like Saccharomyces, play a significant role in its health benefits. These microorganisms contribute to gut health and produce beneficial compounds such as amino acids, organic acids, sugars, polyphenols, and vitamins, adding to kombucha’s nutritional profile.

Numerous in vivo and in vitro studies have highlighted the health-promoting effects of kombucha. These include anti-inflammatory, antioxidant, antibacterial, anti-diabetic, and anti-carcinogenic properties.

Additionally, it has been shown to reduce cholesterol levels and improve liver metabolism, immune system function, and gastrointestinal health. The high antioxidant potential of kombucha is particularly noteworthy, and it largely depends on the type of tea used, the composition of the SCOBY, and the fermentation process.

Potent antioxidants

Green tea, often used in kombucha, is already known for its potent antioxidant properties. Fermentation further boosts these benefits by increasing specific phenolic compounds. These antioxidants help neutralise free radicals, potentially slowing ageing and reducing inflammation.

The hydroxyl groups in phenolic and flavonoid compounds help stabilise free radicals, inhibiting their formation and potentially slowing down the degradation of collagen and hyaluronic acid, which can help decelerate the ageing process.

The bacterial cellulose in the SCOBY, combined with kombucha’s low pH, inhibits harmful bacterial growth on the skin and promotes cell regeneration. The SCOBY has even found applications beyond kombucha production, such as in bio-textile experiments and the adsorption of heavy metals.

Anti-carcinogenic potential

Kombucha’s antioxidant and anti-inflammatory properties have shown promise in inhibiting cancer cell growth. Research has found that kombucha tea extracts can reduce the proliferation of colon cancer cells, suggesting potential anti-carcinogenic benefits.

Organic acids and antimicrobial benefits

Organic acids like acetic, gluconic, and glucuronic acids, produced during fermentation, give kombucha antimicrobial qualities. It has been effective against various pathogens, including Staphylococcus aureus and Escherichia coli.

Liver and gut health

Kombucha may also support liver and digestive health. Its probiotics can enhance gut microbiome composition. Studies have explored kombucha’s hepatoprotective (liver protective) properties by assessing liver function markers, such as serum glutamic pyruvate transaminase and antioxidant enzymes like superoxide dismutase and catalase. For example, Lee and collaborators demonstrated that kombucha improved liver function and reduced inflammation and fibrosis in insulin-resistant mice.

Kombucha and longevity

There is growing interest in the potential of kombucha and other fermented foods to promote healthy ageing. A recent study suggests a connection between probiotics and the gut-brain axis, emphasising the importance of rigorous trials to understand better the role of fermented foods like kombucha in healthy ageing.

The tea matters

The type of tea used in kombucha fermentation is crucial to its health benefits. Green tea, with its high polyphenol content, particularly EGCG (epigallocatechin-3-gallate), offers stronger antioxidant properties than black or oolong teas, making it a superior choice for brewing kombucha. Therefore, kombucha brewed with green tea may offer more substantial health benefits than black or oolong tea.

Recent research and clinical trials

A recent clinical trial explored kombucha's effect on blood sugar levels. A study conducted by scientists from the Department of Food Science and Technology, in collaboration with clinicians from Georgetown University Medical Center and MedStar Health, investigated kombucha’s potential as an anti-hyperglycemic agent. The study, albeit limited in scope with only 12 participants, involved drinking eight ounces of kombucha daily for four weeks. The results indicated a significant reduction in blood sugar levels, dropping from 164 to 116 milligrams per deciliter, while no notable changes were observed in the placebo group. Although this was a small pilot study, it underscores kombucha’s promise as a functional beverage for managing blood sugar levels.

Conclusion

Kombucha is more than just a trendy drink; it's a powerhouse of bioactive compounds with various potential health benefits. From supporting gut health to providing antioxidant and anti-inflammatory effects, kombucha is a delicious and healthful addition to any diet. However, more research is needed to fully understand its benefits, making it an exciting area for future studies in functional foods and wellness.