PARTICLE 101: KOMBUCHA

Kombucha – or ‘booch’ – is a fermented tea that tastes like fruity vinegar or ‘healthy’ soft drink. 

It was first brewed in China around 2200 years ago.

As trade between Asia and Europe grew, the drink spread through Russia and into Europe.   

Today, it’s our friends across The Ditch who are the most curious about booch brewing. 

New Zealand tops per capita global Google searches for ‘kombucha scoby’.

_{Source: Google Trends} 

SCOBY-WHO?

To make kombucha, brewers take green or black tea, add sugar and scoby. 

Scoby (or symbiotic culture of bacteria and yeast) is a slimy, rubbery layer that floats at the top of the liquid. (Sounds gross, we know.)

_{Caption: The scoby may look like a layer of fat, but it’s actually a stack of many thin layers of cellulose. It’s made by bacteria in the kombucha and is home to millions of symbiotic yeasts and bacteria that ferment the tea.
Credit: Mgarten via Wikimedia Commons}

The tangy flavour comes from a symbiosis between bacteria and yeast that live on the scoby. 

The yeast converts the sugar into alcohol and the bacteria convert the alcohol into acid. 

THE HEALTH CLAIMS

Kombucha contains polyphenols, which come from its parent ingredient, tea.

Studies show consuming polyphenols is linked with reduced risk of cancer, neurodegenerative diseases, cardiovascular diseases and diabetes. 

Other sources of polyphenols include green vegetables, berries and dark chocolate.

Kombucha is also full of microbes. Drinking it regularly may increase the diversity of microbes in your gut.

High diversity of gut bacteria is linked with a decreased risk of dementia and several cancers.

But while promising, these studies haven’t tested this on humans. Researchers have only looked at animals, cell cultures or basic chemical structures and then extrapolated this information to humans.  

The human body is complex, and the only way to be certain of the health impact of kombucha is to study its effect on our bodies.

TESTING, TESTING

A recent systematic review of human studies on the benefits of kombucha found just four studies across the English and Spanish-speaking world. The four studies were small and had conflicting results.

One found kombucha has no benefit but possibly negative effects in people who are already healthy. 

Another study on people with irritable bowel syndrome showed it significantly reduced symptoms. 

Two studies of people with diabetes showed kombucha may help them better metabolise sugar. 

While these health benefits are encouraging, more human studies are required to collect more data.

But scientists do agree on one thing: kombucha is healthier than sugary drinks or alcohol.  

THE RISE OF BOOCH

The real hero in the rise of kombucha brewing popularity was the COVID-19 lockdowns.

Global Google searches for ‘kombucha scoby’ peaked in May 2020, 1 month after ‘sourdough starter’ peaked. (Remember when everyone was baking sourdough?)

_{Source: Google Trends}

With the curiosity of the world piqued, it’s time for scientists to do more human testing on the health benefit claims – and for us to do more tasting of this fermented fizzy drink.