It’s an unusual-sounding concoction that has become a top-selling drink. Kombucha, guzzled with trendy abandon by celebrities, hipsters, and gym rats everywhere, is created by adding a colony of bacteria and yeast to black or green tea and sugar. The mix ferments, creating an “elixir” containing vinegar, B vitamins, and other compounds. The concoction is sometimes referred to as “mushroom tea,” as the symbiotic culture of bacteria and yeast (SCOBY) creates a mushroom-like film atop the beverage during its fermentation.

Kombucha's proponents claim it can improve digestion, stimulate the immune system, and even cure diabetes, AIDS, and cancer. Unfortunately, there is no scientific evidence to support these claims.

As with so many “wonder cures,” kombucha's marketers hint that their concoction dates from ancient times in the mystic Orient. The historical truth is significantly less intriguing than the “lore.” There is no known or documented consumption of the drink before 1900, when it first appeared in Russia. From there, it migrated westward into Europe. The drink should not be confused with konbucha, which is a very healthy tea made from the seaweed konbu.

Why the buzz? Other than bottling companies needing new products to supplant sugary drinks whose popularity have happily taken a nose-dive in the last several years, there must be some basis to kombucha's health claims, right? The hook is in the probiotic nature of the SCOBY.

Although the actual composition of each brewer's SCOBY varies andallows for each bottler to tout their own unique “secret formula.” The yeast typically contains traces of various probiotics. These are the so-called “good bacteria,” or “gut flora,” microorganisms that live in the intestinal tracts and, by definition, confer some kind of beneficial effect. Different strains of probiotics have been alleged to ameliorate high blood pressure, lactose intolerance, and various types of gastroenteritis. But even in their most base and pure forms, only preliminary evidence exists. Neither the FDA in the US nor the European Food Safety Authority have approved the health claims by any probiotic distributor. The micro-organisms are also made available for consumption in capsule form, as well as fermented dairy products and “probiotic fortified” foods.

Now, some more caveats.

The popularity of kombucha has spawned a sort of cottage industry for homemade starter batches. Backyard brewers trade “daughter” SCOBYs from their “mother” batches the way bakers swap sour dough starters. It's darling, to be sure, but it's not always antiseptic. In fact, non-sterile home conditions make contamination a high-probability, and lead poisoning is a concern where ceramic-glazed pots are using for brewing.

There is also an ongoing concern regarding the alcohol level in kombucha. There was a massive, shelf-clearing recall in 2010 when it was revealed that many brands of the brew had an alcohol content well in excess of the legal limit for the category. The controversy continues on, as last autumn the U.S. Alcohol Tobacco Tax and Trade Bureau notified several manufacturers that their fermented brews contained too much alcohol and that they would have to pay up if they did not change their formulas.

In short, if you like the taste of kombucha, by all means drink it, preferably out of bottles purchased from reputable sellers, but do not look to it for any curative or other health benefits other than quenching your thirst.