No longer something your hippie aunt insists you take a sip of when you visit, the fermented tea drink, fondly known as "booch" by its fans, can be found on supermarket shelves in a variety of brands and flavours.

At Coles, depending on the brand, a liter of kombucha will set you back at least $6, compared to about $3 for a two-litre bottle of diet coke.

If you choose to buy from a small-scale producer the cost could climb to between $14 and $20 a litre.

As to whether it's worth the extra cash, the answer is - it depends.

Michael 'Mouse' Turner owns the Booch Bar in Mangerton, Wollongong, south of Sydney, and he said one of the first things he asks his customers is why they're interested in kombucha.

"If it's a soft drink replacement I'd say save your money, go to woolies, buy whatever's on special, drink that and be happy it's not coke," he said.

"If you want it for the probiotic have 100-150ml from a small batch brewer on an empty stomach - you don't need any more.

"Don't get me wrong, it's great if you're drinking a litre of mine a day but there's a misconception that you drink it like a soft drink and that's not really how it should be consumed."

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There is also some debate about what products should be allowed to label themselves as kombucha.

Some supermarket kombucha drinks contain a kombucha concentrate as a base, and are topped up with flavours and sweeteners.

This can lead to confusing nutrition panels, with high carbohydrate and low sugars and kilojoules.

Damien Belobrajdic, a nutrition physiologist at the CSIRO, said that was because some sweeteners called sugar alcohols cannot be used as energy by the body.

"It would be recognised as a carbohydrate but it doesn't provide digestible sugars," he said.

"That carbohydrate isn't being used as energy, so there's a lower number of kilojoules."

Mr Belobrakdic said the jury's still out on any potential health benefits of kombucha.

"A carefully controlled clinical study is needed in this space," he said.

"Currently the main recommendation for improved gut health is to increase your fibre intake, and for people to consume water as their preferred drink.

"It's an unknown - there is the potential for health benefits but no studies are available to demonstrate those benefits.

"However if people enjoy the taste there's no reason not to drink it, and a lower sugar flavoured beverage will generally be a better choice than a highly sweetened soft drink."