The term "kombucha" refers to the fermented tea which results from a kombucha mushroom floating in a jar of liquid.  It all begins with the "mother," which is also variously called the "starter," "culture," "mother of vinegar," "mushroom," or "SCOBY."  The last term, an acronym for Symbiotic Colony of Bacteria and Yeast, is the most scientifically accurate, if the least evocative.

The SCOBY looks like a fat pancake, and floats at the top of the jar.  It bears a physical resemblance to a big flat mushroom, which is why some people refer to kombucha as a mushroom.  But a mushroom is a single fungal entity, whereas the kombucha SCOBY is a collection of several different kinds of bacteria and yeast, all growing together in a spongy mat.

Incidentally, I had a friend in college who developed problems with her kitchen sink.  Her landlord was right angry when he hired a plumber who diagnosed the problem as being due to a kombucha culture which she had dumped down the sink.  It had been growing down there in the darkness for months, and eventually stopped the drain.

Reports of kombucha's health benefits are typically thought to be due to the bacteria and yeasts which are present in the juice.  These are beneficial organisms, not too unlike what you get in yogurt.  Additionally, because the kombucha tea is fermented, it is ever so slightly alcoholic, which adds to its deliciousness and the afterglow of well being after having a glass.

To make kombucha tea, you drop a SCOBY into a jar full of black or green tea and let it get to work.  The kombucha organisms digest the sugars in the tea, and release their own juices, and the resulting fermented beverage can be poured off and drunk.  In this respect, kombucha is similar to sourdough starter.

Kombucha's history is shrouded in the antiquity of the East, which also helps add to the mystique and supposed healing powers of the beverage.  Kombucha is a traditional part of Russian, Chinese, and Japanese culture.  

Kombucha tea contains a wide and varied collection of chemicals, most of which are acids like lactic acid, oxalic acid, and of course acetic acid (vinegar).  There is some evidence that habitual consumption of kombucha tea can cause liver and kidney damage - perhaps unsurprising, since kombucha tea certainly contains substances which your liver and kidneys will feel obliged to filter out.  (That is, after all, what they do.)  That being said, you have to consume an awful lot of kombucha tea to risk liver damage.  

The CDC has a report on two people who fell seriously ill after regularly consuming kombucha tea, daily for several months.  The toxicity was caused primarily through acidosis of the blood.  Kombucha is quite acidic, and if you are already ill (as both patients were), you should be careful how much you drink.

There are so many health benefits ascribed to kombucha tea that it's difficult to tell truth from placebo, so to speak.  However, the bacteria in a kombucha culture are certainly known to be beneficial, and a lot of people really like the taste, which is reason enough to give it a try!

Creative Commons-licensed picture courtesy of Flickr user Ocean of Stars