Kombucha is made from either a green or black tea base, with some interesting additions. Matt Hoffman
The drink kombucha was previously only popular in hipster cafes, but is now vying for space on the supermarket shelves. Many claims are made about the health benefits of drinking kombucha, but what does the science say?
For those of you who haven’t tried it, kombucha is a quirky-tasting drink. Depending on what’s added to it, it’s best described as a sour apple cider, perhaps with vinegary notes.
Kombucha is an ancient beverage that was originally consumed in China more than 2,200 years ago for its detoxifying and energising properties. As trade routes expanded, kombucha found its way to Russia and then into other eastern European areas.
During the second world war, kombucha was introduced into Germany, and in the 1950s it became popular in France and North Africa. By the 1960s, Swiss scientists claimed that kombucha was beneficial for the gut in a similar way to yoghurt.
Kombucha is made from either a green or black tea base. Added to that is white sugar, which has been fermented with a type of “tea fungus” called a symbiotic culture of acetic acid (vinegar) bacteria and yeast, or SCOBY, for one to two weeks.
Detailed scientific recipes are available for how to prepare kombucha. The taste of the kombucha changes during fermentation from a pleasantly fruity sour-like sparkling flavour, to a mild vinegary taste after a long incubation period.
The SCOBY is a type of ‘tea fungus’. Sterling College, CC BY
The fermentation process is important, as the SCOBY changes the polyphenols – compounds normally found in tea, fruits and vegetables – into other organic compounds. This increases the acidity, which prevents other micro-organisms growing.
It is these new organic compounds that are claimed to provide health benefits beyond those already found in green or black tea.
The fermentation process extends the shelf-life of kombucha, as it does with other historically popular foods and drinks such as cheese, yoghurt, sauerkraut, kimchi, wine and beer.
Beer and wine become alcoholic during the fermentation process, whereas kombucha generally contains less than 0.5% alcohol. Food Standards Australian and New Zealand classifies foods and drinks below 0.5% as non-alcoholic.
Ethanol, the alcohol you can drink, is produced when the yeasts and bacteria in the SCOBY interact via a process called glycolysis. The acetic acid bacteria in the SCOBY make use of the ethanol to produce vinegar (acetic acid), which contributes to its sour taste.
Lightly fermented foods, made from bacteria, contain healthy bacteria. The theory is that these bacteria help colonise our gut, which early research suggests may improve a range of bodily functions from our mood and stress levels, to our weight and cravings for food.
But simply ingesting healthy bacteria won’t necessarily cause these bacteria to permanently live in, or colonise, the gut. To gain any long-term health benefits from foods containing live bacteria, known as probiotics, the current research suggests you would need to take them continuously.