What is Kombucha?
Is the case of kombucha one where some seriously good marketing has outweighed the scientific research? I’ve reviewed the evidence to find out if there is any scientific backing to support the claims, but first and foremost, what is kombucha?
Kombucha is a fermented tea, usually made with black tea or green tea, sugar and a Symbiotic Culture Of Bacteria and Yeast (SCOBY for short - google SCOBY images to see what I’m talking about here).
The fermentation process of kombucha naturally adds fizz. During the process different flavours can be added to the end product, for example, ginger, lemon, raspberry, lime, strawberry etc. to make a flavoured kombucha drink product.
Whilst sugar is added at the start of the fermentation process, the bacteria and yeast (in the SCOBY) essentially feed on the sugar and by the end of the process the sugar has been consumed by the SCOBY (see my note below on sugar in kombucha!).
Kombucha is constantly marketed as good for gut health and the SCOBY is comprised of microorganisms including acetic acid, that gives it that vinegar tang and the fermentation process produces vitamins, minerals, amino acids and enzymes.
What does the research say?
Research into the health benefits of kombucha in humans is limited. Very limited. Actually, it's non-existent, which might come as a surprise given how much hype surrounding kombucha there is.
There have been 2 systematic reviews* of evidence over the years. One in 2003 and one in 2018.
There is one piece of research in 2002 that shows a positive effect on blood glucose levels in type 2 diabetes patients who trialled 60ml kombucha for 90 days. There are no gut-specific trials that I could find anywhere that have been conducted on humans!
There is some research into the benefits of some of the compounds derived from tea and the fermentation process of kombucha such as the benefits of polyphenols and acetic acid. For example, polyphenols are a good source of antioxidants and acetic acid can help to regulate blood glucose levels.
Some animal studies have been undertaken on kombucha and there is no research that determines the effect on our gut bacteria and whether it has beneficial probiotic effects. Increasing plant diversity is beneficial for gut bacteria and that is one theory that could support the consumption of kombucha.
Thoughts on kombucha...
Like many research topics, just because there isn’t currently any evidence it doesn’t mean kombucha isn’t beneficial - it just means that to date there is no research to support the claims and what we don’t currently know about kombucha is how much beneficial bacteria it contains, the strains of bacteria and whether it survives the digestive process to make it to the gastrointestinal tract to provide the suggested health benefits.
As I mentioned above, the ingredients have their own health benefits, so if you like kombucha enjoy it for what it is - a fizzy drink. It’s also an amazing option if you are looking for no/low sugar fizzy drink options and I often recommend it to clients as a good alternative to other drinks loaded with sugar.
I recommend reading labels and checking the sugar content. Brands such as Remedy Kombucha (my personal favourite) don’t contain any sugar but there are plenty of other products out there that have added sugars for a sweeter flavour.
As always, I am committed to thoroughly researching the topics I share with and you and if you have seen a piece of research that I haven’t highlighted or one that offers a different outcome to the studies I’ve mentioned above, I’d love to have a read, because as much as I try and stay across the science, it’s a world that changes by the day.
* A systematic review is the gold star of scientific research, it essentially does a sweeping search and review of all evidence across all databases available.
Amy Savage is a qualified Nutritionist with a Bachelor of Health Science in Nutritional & Dietetic Medicine and is available for consultations online and in Sydney CBD. Email amy@amysavagenutrition.com for further details.
Recommended reading:
If you are interested in some further reading on gut health, you might like my article on What is Leaky Gut?
References:
Kapp et al. 2018, ‘Kombucha: a systematic review of the empirical evidence of human health benefit’, Annals of Epidemiology, https://www.sciencedirect.com/.
Liljeberg, H & Bjorck, I 1998, ‘Delayed gastric emptying rate may explain improved glycaemia in healthy subjects to a starchy meal with added vinegar’, Journal Clinical Nutrition, https://www.ncbi.nlm.nih.gov/.