We love to ferment things, with one notable exception: kombucha. During the last kombucha craze, in the mid-90s, we picked up a “SCOBY” blob and dutifully fed it tea and sugar until we stumbled upon an article written by mycologist Paul Stamets, “The Manchurian Mushroom: My Adventures with “The Blob.” In that article Stamets tells a convoluted story of having a kombucha culture tested by a lab. He didn’t tell the lab what it was.The lab was very excited about the results on this mystery substance, and Stamets soon finds himself “sitting in a board room of a pharmaceutical company with lawyers and contracts discussing the particulars of patents, sub-licensing agreements, market territories, and dollars running into the millions—if FDA approval was granted for a novel drug.“

Then the folks in the meeting turn to Stamets and ask him to reveal the identity of this culture:

I told them that, as best as we had been able to determine, from analyses by several independent mycologists, that the Blob was a polyculture of at least two yeasts and two bacteria, living synergistically.

The silence was deafening.

“Say what?”

Perplexed looks crossed their faces, soon followed by exasperated expressions of deep disappointment. Which of the organisms are producing the potentially novel antibiotic? Was it one or several? Was it one in response to the presence of another organism? Was it one in response to several organisms? The sheer numbers of permutations would complicate trials and given the FDA’s disposition, a polyculture is de facto contaminated.

The meeting was abruptly adjourned.

So kombucha does indeed have medicinal properties–including “novel antibiotic” properties– but therein lies the problem. Stamets concudes,

Those who might benefit from Kombucha need a credible and experienced professional who could best prescribe and administer it. I do not see the advantage of taking Kombucha by people in good health. Given the detrimental effects seen from prolonged exposure to antibiotics, the repeated, long term use of Kombucha may cause its own universe of problems. I wonder about those people who have adverse reactions to antibiotics? What about those with sensitivity to the microorganisms in Kombucha? I personally believe it is morally reprehensible to pass on this colony to sick or healthy friends when, to date, so little is known about its proper use. At present there are no credible, recent studies as to the safety or usefulness of Kombucha, despite decades of hype.

Stamets also expreses concern over contamination. A German study found three out of 32 samples of kombucha cultures taken from German households to be contaminated with Penicillium spp. and Candida albicans. While describing the contamination rate as “low” (nearly 1 out of 10 samples seems high to us) it goes on to recommended that immunosuppresed individuals buy commercial kombucha instead of making it at home. A literature review conducted by the Universities of Exeter and Plymouth in the UK concludes, “the largely undetermined benefits do not outweigh the documented risks of kombucha,” said risks including, “suspected liver damage, metabolic acidosis and cutaneous anthrax infections.”

We’re all for fermented foods, and support the home fermentation of classic pro-biotics like yogurt, sourdough and lacto fermented vegetables. The last thing we want is for people to get spooked away from home fermentation. But kombucha is different. The problem, as Stamets notes, is that kombucha’s sugar and tea medium is a kind of open house for cultures, some good, some bad. Yogurt, sourdough and salt brines are very selective mediums in which to ferment things. With komucha it’s much more of a crap shoot.

Basically, like Stamets, we’re intrigued with the notion of kombucha being tested as a medicine and used with care by both western medical types as well as herbalists. And even if we were guaranteed a pure culture and a solid methodology for keeping the culture uncontaminated, we’d still be too leery its antibiotic properties to consider it a casual beverage. So we just don’t do the kombucha thing.