What is Kombucha?

Kombucha is a purported health drink that is all the rage among health nuts. But what is really known about this lightly fermented tea?

Kombucha is actually a misnomer. The Japanese name for what English speakers call Kombucha is kōcha kinoko, which literally translates as "toadstool tea."

Kombucha is made by adding a fermentation agent to sweetened black tea (other types of tea also may be used). The fermentation agent is a symbiotic colony of bacteria and yeast (SCOBY), which when added to the sweetened tea, forms a microbial mat on the top of the liquid. The mat contains bacterial cellulose and is so firm that it can actually be used to manufacture a form of artificial leather. The mat also helps prevent contamination of the liquid beneath, although when contaminants are found growing on top of the mat, the entire batch is usually discarded for safety reasons.

The fermenting agent in kombucha is not an actual mushroom or toadstool, although it is often casually called the kombucha mushroom because of its solid and leathery appearance. The mat also often sends bacterial "threads" into the liquid portion of the brew, which may contribute to its mushroom-like appearance.

The yeast in the SCOBY converts sugars in the sweetened tea to alcohol, which the bacteria then convert to acetic acid (vinegar). This makes kombucha a somewhat acidic beverage with a low alcohol content. The acidity and alcohol helps prevent contamination of the drink, making kombucha fairly easy to prepare and maintain in non-sterile conditions. By the same token, contamination can be a problem in improper kombucha manufacture, such as home brewing, leading to adverse reactions when consumed. Kombucha products often contain more than 0.5% alcohol by volume, though some contain less. People with alcohol sensitivity are advised to read product labels carefully.

The purported health benefits of kombucha are unsubstantiated by science, but analysis of the beverage has shown that it contains high levels of B vitamins and potentially healthful micronutrients, most notably glucuronic acid, used by the liver for detoxification.

Because it contains bacteria and yeast molds, allergic reactions to kombucha are possible.