Tag Archives: kombucha

Kombucha: The Science and The “Science”, Part I

But before getting to the benefit question, it should be noted that there have been case reports of negative health outcomes from kombucha. The key thing to notice here is “case reports.” These have been few and far between, despite titles like “Kombucha–toxicity alert.” To be fair, there are things to watch out for. First, the way you make kombucha is putting sugar in tea, thus there is always a risk of contamination (although it has broad-spectrum antibacterial properties, http://dx.doi.org/10.1021/jf991333m). Second, human allergies/sensitvities are varied; if you are allergic/sensitive to what the SCOBY produces, you’re going to have issues. For example: “A case of Kombucha tea toxicity.” The patient shared a bottle of kombucha with a buddy. The buddy had zero effects from the kombucha whereas the patient was up a creek for a while. One possibility is that, having a compromised immune system, the sudden influx of microbes that should in theory stimulate the immune response (see below) instead sent his body into chaos. Or perhaps it was a sensitivity to the output of the microbes. Or perhaps it had nothing to do with the kombucha and the acute toxicity was due to something else. Here is another case study “Unexplained severe illness possibly associated with consumption of Kombucha tea” Two women ended up in the ER, one of them subsequently died. The thing to note is that 115 other people had been drinking kombucha from the same source of SCOBY and were fine. The other thing to note is that this was made at home. Commercial products tend to be standardized as to potency. At home you can make it strong. Very strong. Undrinkably strong, unless one espouses the view that extra strong taste means more health benefits, which some people do. Thus this might be a case of kombucha overdose, rather than ‘cosumption’ per se. In general, the way in which the medical community approaches the question of kombucha toxicity seems to be more “science” than science, and statements such as “Consumption of Kombucha tea should be discouraged, as it may be associated with life-threatening lactic acidosis” betray a naïve approach to health/harm that, to my mind, is on par with people on the internet who claim that kombucha, or anything else, is the magic potion to cure everything that ails you. Scattered incidence of potential toxicity are about as convincing to me as scattered incidence of potential curing of illness.

But onto the science! As in the peer-reviewed, experimental kind, not the speculative kind.

One early study looked at mice living out their (sort of natural) lives without interruption in a lab (http://dx.doi.org/10.1016/S0899-9007(00)00380-4 ). The most notable effect was that the mice fed kombucha lived longer. However, this might be due more to the tea aspect of the treatment rather than kombucha per se. Still, this does tend to support the idea that kombucha is non-toxic. A study done on rats (http://www.ncbi.nlm.nih.gov/pubmed/11351863) looking at acute toxicity also failed to find any negative effects of kombucha. Indeed, not only was there no toxicity found for kombucha at “regular” does, even more “extreme” doses failed to induce toxicity (http://www.ncbi.nlm.nih.gov/pubmed/11723720) and, indeed, showed some interesting benefits, including lower stress response to cold or hypoxia, although, again, this may have had more to do with the tea part of kombucha rather than anything specific to the SCOBY.

Feeding kombucha to rats has been shown to prevent the toxicity induce by chromate(VI) which is a potent oxidant (as in causes the kind of damage that you consume antioxidants to avoid), although here again, there was no “tea only” control (http://dx.doi.org/10.1016/S0378-8741(00)00161-6 ). Similarly, kombucha reversed at least some of the problems of lead ingestion (http://www.ncbi.nlm.nih.gov/pubmed/14631833 ). Similarly, kombucha prevented toxicity due to phenol in mice (http://www.ncbi.nlm.nih.gov/pubmed/21387911 ). However, the few studies that have compared kombucha with not only water control but tea as well seem to suggest that there might be something special about kombucha. For example, although black tea, black tea with some kombucha based enzymes, and kombucha all reduced the toxicity of carbon tetrachloride (http://dx.doi.org/10.4014/jmb.0806.374 or go to http://www.jmb.or.kr/journal/viewJournal.html?year=2009&vol=19&num=4&page=397 ), the kombucha group did better than the other two groups. The authors speculate that there might be some antioxidants produced by the SCOBY that are not present in tea. Similar benefits of kombucha over tea were reported for dealing with trichloroethylene toxicity (http://dx.doi.org/10.1186/1749-8546-4-23 ). The importance of this finding is that trichloroethylene is a common industrial solvent which does all manner of damage to the human body. On a more mundane yet perhaps also more relevant to daily life level, kombucha was found to not only more effective than tea at ulcers (in mice) its efficacy was on par with omeprazole, aka Prilosec  (http://dx.doi.org/10.1039/C0FO00025F ). Although the authors suggest that this could have been due to kombucha reducing gastric acid release, another possibility is that the effects were more at the source, as kombucha inhibits the growth of Helicobacter pylori (http://dx.doi.org/10.1021/jf991333m), which is the bacterium responsible for ulcers in humans. Finally, kombucha was recently found to improve outcomes for diabetic rats (http://dx.doi.org/10.1186/1472-6882-12-63 ), in terms of blood sugar and blood lipid content. Again, kombucha was found to be better than just plain black tea.

So there you have it. Kombucha is unlikely to harm you and could potentially keep you in better health. If nothing else, it is certainly a very tasty drink and definitely healthier than chugging a soda.  

The Microflora Menagerie Thus Far

Ginger beer:

Got dehydrated ginger beer plant from here which is composed of Brevibacterium vermiforme and Saccharomyces florentinus (thus making it a SCOBY). This is relevant as apparently there is a number of places that sell “ginger beer plant” which is just overpriced yeast for brewing. There’s an interesting article in the New Scientist about an English dude who studied ginger beer plant and got samples from all over the world and the common microflora in all of them were the aforementioned bacterium and yeast.

Why is this “authenticity” important? To some extent, it isn’t, at least not to me. The main reason why I care is that it would be interesting to have different flavor profiles, depending on which SCOBY gets used, much as one gets different flavor profiles from different grape varieties. After all, the reason not to simply using only yeast is because the bacteria produce their own set of organic acids and other compounds and thus impart a flavor beyond ethanol.

Right now, I’m brewing a second batch. Had one bottle of the first batch and it was quite nice. Definitely different from ‘ginger beer’ I’ve had thus far. There are some sour spectrum flavors which are interesting. The next step is comparing how ‘aging in the fridge for two weeks’ ginger beer tastes like versus ‘aging for a week’ ginger beer tastes like. A project that would be a more authentic experiment if the process were the same in both cases… which it wasn’t, if for no other reason than the first batch was the first rehydration of the ginger beer plant.

Water kefir:

Or, tibicos. Another SCOBY. Unlike ginger beer plant, this one doesn’t seem to have a common bacterial and/or yeast profile from what I understand. To some extent, it seems like ginger beer plant might be a specific variety of tibicos. Certainly they look quite similar. The main difference seems to be that the ginger beer plant grains float up to the top of the brew while tibicos grains hang out at the bottom, suggesting that the composition of the SCOBYs is different.

Thus far I’m still ‘reviving’ them from their dehydration. Another difference from the ginger beer plant which went right to work, these seem to be taking their time in getting going.

As a side not, I find it interesting that they are sold as “water kefir” grains and not tibicos. Seems like a marketing thing. Kefir already has a “healthy drink” aura about it. It’s unclear to me that this particular combination of bacteria and yeast has any particular health benefits but I’ll be looking into that once there is a batch ready for drinking.


This is a culture that I am growing from a bottle of G.T.’s brand kombucha. Already made one batch before moving to Miami and it was pretty awesome. Basically at full concentration, it tasted like a sweet fruit vinegar, reminiscent of apple cider. I’d used a jasmine green tea for it. Unfortunately, that SCOBY died. But not in vain! I learned that you cannot grow kombucha on rooibus tea. This might be because: 1) rooibus has some antimicrobial properties that killed either the bacterial and/or the yeast portion of the kombucha culture, or 2) kombucha in fact needs caffeine to thrive. I’m rather fond of the second hypothesis. A culture that decides to stake a claim on caffeinated beverages. Once this new culture forms a nice solid colony, I’ll try a batch on yerba mate that I bought recently.

Interesting side note, the particular variety of kombucha I’m using has the bacterium Bacillus coagulans, which is apparently added to animal feed because it boosts the immune system. This fact, more than anything else, would suggest to me that it does, in fact, have beneficial properties. The yeast is Saccharomyces boulardii. What I find interesting about this species is that apparently it sets up camp in your gut and entices E. coli to attach to it, rather than to your intestinal lining. Seems like a handy yeast to have around.

I’ll have more to say about kombucha in the coming week or so, including links to relevant studies.


First batch ever. Shredded a small head of organic red cabbage, put it in a jar, layering some salt and muddling it every few inches. Topped the whole thing off with water. And then sealed the jar.

What? Yes, sealed it. Why? For science! To see how much gas is produced. The answer: quite a bit in the first 24 hours. Made the mistake of unscrewing it in my pantry, not over the sink. Oops. As you might imagine, bright pink liquid squirted all over the place. BUT the sealing might have worked to my advantage in terms of pushing fermentation in the direction I wanted. In case it’s been a while since you’ve slept through organic chemistry, when carbon dioxide dissolves in water it makes an organic acid. Given that desirable fermentation involves bacteria that like acidic environments, this probably helped give these and advantage over their competitors. It certainly softened up the cabbage quite nicely.

Since then, in the past week and a half, the wide mouth of the mason jar has had a small mason jar filled with water as the cover. This did require adding extra water every other day as the air in this apartment is dry enough as to make the loose seal result in significant evaporation. Today I filled the jar up to the top with water and resealed it tightly. Tomorrow I’ll unscrew it and see how much gas formed this time around. If the fermentation has gotten where I think it should have, the answer should be relatively little gas. In the meantime, the smell seems to be that of fresh sauerkraut, which is encouraging… and yummy.

Preserved lemons:

A North African project. Apparently a fast ferment that makes the whole lemon eatable, as in the rind as well. Lemons are quartered, salted, and muddled. Topped off with water. Apparently, unlike with other ferments, having some bits float above the water level is not a problem. We’ll see. Fortunately, the kind of mold that seems to grow on citrus is fairly easy to spot. I used organic lemons which had a nice thin rind so I have high hopes of the fermentation magic to work here, in contrast to thicker rinds where I might be worried about full penetration of whatever chemical magic must happen.


Fairly basic. Got organic low fat Greek style yogurt, put a heaping tablespoon into a half gallon of low fat milk, whisked it, left it in a covered pot for the night and… yogurt. Milk just at room temperature. I suspect that if I weren’t using it for smoothies, I’d actually want to heat it so it would ‘set’ properly. As it is, I enjoy the simplicity.

Those are the ongoing projects. Tomorrow I’ll write up the exciting NEW projects that got started today. Stay tuned.