What actually is kombucha?
Kombucha or 'booch' is a fermented tea drink made using a starter culture called a SCOBY (symbiotic culture of bacteria and yeast) or Mother. The SCOBY is basically a microbial biofilm made of cellulose and is home to a range of different bacteria, including acetic acid bacteria (bacteria which produce acetic acid or vinegar as a byproduct of fermentation) and yeasts. These microbes ferment the sugars and other tea components in the sweet tea you add at the beginning of fermentation.
As you can hopefully see in the picture above the Mother or SCOBY looks and feels a bit like a jellyfish and grows to fill the shape of the container the kombucha is made in. You can either acquire a SCOBY from a mature Mother or grow a new one from a ready-made bottle of booch.
A lot is going on in a jar of kombucha as it brews but put simply the yeasts ferment the available sugars to alcohol and the bacteria convert the alcohol to acetic acid. The result is a sour and sweet, fizzy drink with low levels of alcohol (typically less than 0.5%).
What does the current evidence say?
Much of the current evidence for kombucha has been done in the lab or in animals such as mice, using models of disease to test for any potential benefits. Some of the benefits seen in these types of studies include beneficial effects on blood glucose control and elevated cholesterol levels, effects on the gut microbiome and reduced inflammation (1).
To date though there have been no controlled human trials using kombucha. It's this evidence that we need to really start to understand health benefits of foods which basically means that we just don't know what kombucha does when humans drink it.
A recent study looking at the strength of evidence behind common health claims found that health claims for kombucha have the least amount of evidence to support them. This basically means there a lot of unsubstantiated claims being made about what kombucha can do for you (2).
There's a lack of evidence for kombucha being harmful though. Although there are a few case reports comprising a handful of people presenting with symptoms after consuming kombucha it's considered very safe for most of us. There are many other foods with much worse reputations for making you ill - looking at you chicken!
Who might want to avoid it?
Those who want to be careful of their sugar intake (such a diabetics) may not want to drink too much, although with good blood glucose management there should be little problem. Also, those with alcohol dependencies or pregnant people might want to steer clear as the level of alcohol isn't guaranteed unless you actively measure it. Commercial kombucha producers are required to prove that their drinks contain less than 0.5% alcohol, however.
So, what do we know..?
Okay, so although we don't know much about specific health benefits we do know (for sure!) some things about booch. Firstly, if you drink raw, unpasteurised kombucha then it's a source of live microbes like bacteria and yeasts. If these make it to your large intestine intact, then they may have positive effects there. Also, if swapping your usual tipple to a glass of booch helps you drink less alcohol then great, that alone will help improve your health. Lastly, tea itself is packed full of phytonutrients, such as catechins and theaflavins, which we do know are beneficial to supporting good health.
The types of kombucha you can make are endless, using different types of tea and flavourings, fermentation times and secondary ferments. This makes it very fun to make and if you take care of your SCOBY you can keep making it for as long as you want! So if you enjoy making and/or drinking kombucha then go ahead. Just don't expect it to cure you of, well, anything (other than a hangover if you drink it instead of your usual pint!).
Check out our Kombucha Workshop dates to come and learn more about this delicious, microbe-packed drink!
2 Online information in Spanish on probiotics, yoghurt, kefir, kombucha, fibre and prebiotics: an analysis of the quality of information and the certainty of the evidence supporting health claims - PubMed (nih.gov)