What is kombucha?

Kombucha is a fermented drink made from sweetened black or green tea. It's produced by fermenting the tea with a symbiotic culture of bacteria and yeast (SCOBY). The fermentation process gives kombucha its characteristic slight fizz and tangy flavour. It can also be enhanced with fruit juice or spices.

The fermentation process of kombucha involves several steps:

1. Black or green tea leaves are steeped in hot water - then sugar is added.

2. The mixture is introduced to bacteria and yeast and left to ferment at room temperature for 1-2 weeks.

3. During fermentation, the bacteria and yeast produce a cellulose layer on the surface.

4. The resulting fermented liquid is the kombucha tea that we drink.

Kombucha contains caffeine - but in much smaller amounts than coffee or tea.

Dr Raj Dasgupta, ABIM quadruple board-certified physician says that kombucha has some caffeine in it because it's brewed from tea - which naturally contains caffeine.

"The exact amount can vary based on the type of tea used and how it's brewed," he explains. "If you're keeping an eye on your caffeine intake, it's worth checking the label or asking about the tea base when choosing kombucha."

Kombucha makes small amounts of alcohol during fermentation - usually less than 0.5%. The longer the kombucha ferments, the higher the alcohol content becomes. Dasgupta explains that shop-bought versions are generally safe, though there may be a slight chance of harmful bacteria if it hasn't been brewed or stored correctly. Only buy kombucha from trustworthy sources.

Kombucha's potential health benefits continue to be explored. The acids in kombucha may help friendly gut bacteria growth. But contamination during fermentation might cause additional health conditions such as an imbalance of acid in your body (metabolic acidosis). Kombucha's high acidic levels could also damage the enamel in your teeth, which could lead to tooth decay.

Mohr advises: "Moderation is important when it comes to kombucha - especially if you’re new to drinking it. Start with small servings to lower the chance of harmful effects como inchaço or digestive issues."

Dasgupta adds that - for most people - drinking up to one can of kombucha a day is generally considered safe. However, tolerances may vary from person to person.

Heart disease management and prevention specialist, Michelle Routhenstein, Entirely Nourished, says that people with compromised immune systems or sensitivity to caffeine should use caution when consuming kombucha.

Kombucha's sudden rise in popularity could also lead to safety issues. Poor-quality ingredients, improper containers, and unhygienic fermentation create a chance of toxin contamination. To ensure safety and quality, health organisations should set legal guidelines for production methods, ingredients, and quality control.

Dasgupta warns that if you're pregnant or breastfeeding, have a compromised immune system, or deal with severe acid reflux, stomach ulcers or alcohol sensitivity, it's a good idea to talk to your doctor before trying kombucha.

"Its fermentation process and ingredients could pose risks for these people," he explains.

He adds that kombucha could also interact with certain medicines. This is due to the presence of certain by-products formed during the fermentation process. These by-products could affect how your medicines are absorbed or metabolised in your body.

While safe to drink in moderate doses, kombucha's health benefits lack strong scientific backing. Enjoy it as a refreshing drink, but don't expect it to be a cure-all. Check labels for caffeine and alcohol content, and remember, more research is needed to confirm its health claims.