Can sipping fermented tea REALLY be as good for you as all its fans claim? We examine the Kombucha craze sweeping the nation and the results might shock you
- Kombucha is normally a sour-tasting fizzy liquid with yeast floating on the top
- Fans of the product claim it contains millions of healthy bacteria for your gut
- It is claimed this bacteria can balance microbes in the gut to prevent disease
- However, some products contain as much sugar as a can of fizzy soft drink
It can help lower cholesterol, give you a flatter tummy – and even protect you from cancer. These are just a few of the extraordinary claims that foodies make about kombucha, a trendy new drink popping up on supermarket shelves.
Kombucha is, in fact, fermented cold tea. The yellow, sour-tasting fizzy liquid usually comes complete with remnants of yeast floating in it. Indeed, the health-giving secret lies with the bacteria. It supposedly contributes to the balance of microbes in the gut known to protect us from diseases. But with some versions as sugary as a can of fizzy drink, is kombucha the panacea it is made out to be?
Kombucha fans claim it can lower cholesterol, give you a flatter tummy and even protect you from cancer, but the so-called miracle cure is simply a fermented cold tea
It’s all down to a slimy brown substance
Brewing kombucha involves mixing black tea, sugar and water with a slimy, brown substance called a scoby, a culture of fermented bacteria and yeast said to be the source of its health-giving properties. Similar to the starter used for sourdough bread, the yeast in the scoby interacts with the sugar and water to trigger a proliferation of ‘friendly’ bacteria, similar to those found in probiotic supplements and natural probiotic foods, such as yogurt and sauerkraut.
When consumed, these bolster the bacteria that live in the gut. Often referred to as the microbiome, they form an integral part of our immunity, and help regulate functions from digestion to hunger. But there is a problem. The bacteria in kombucha are different from those in the gut because they are fermented in the presence of oxygen – affecting their behaviour in the body.
Dr Paul Cotter, head of the Food Biosciences department at Teagasc Food Research Centre in Cork, says: ‘This means most of the microbes in kombucha will be killed by the acidic environment of the gut or be excreted out.’ As such, the benefits will be small.
Beware of the hidden sugars
Kombucha sold in shops is a far cry from its ancient Chinese origin which was a simple combination of sugar, tea, water and yeast to kill bacteria in dirty water.
Now it’s a sweetened fizzy beverage with a similar sugar content to that of iced tea. Dietician Helen Bond warns: ‘Some bottles contain up to five teaspoons of sugar, as well fruit juice.’
Effects were studied in mice… not humans
So what of those borderline miraculous health benefits? Drinking kombucha has been shown in small studies to reduce cholesterol and possibly even affect tumour growth rates – but only in mice. Dr Cotter warns: ‘Mice have much shorter digestive tracts so the time it takes food and drink to pass through is dramatically different, and this affects results. The composition of mice microbiome is also very different to ours.‘We’re are a very long way from saying kombucha can protect against cancer, or anything else.’
The uglier the drink looks, the better
Filtered products may look more appealing, with the brown remnants of the yeast mixture removed, but they won’t provide the benefits of an uglier-looking drink. ‘Look for bits of remaining culture at the bottom of the bottle,’ advises Dr Cotter. ‘These are likely to contain more robust bacteria.’
Make your own at your peril
If you want to avoid supermarket stuff, DIY kombucha kits cost as little as £20 online. But proceed with caution. If the liquid is left to ferment in a sealed bottle for a few months, the carbon dioxide gas produced increases the pressure, and the bottle could explode.
Dr Cotter adds: ‘And if the balance of yeast to water is off and the kombucha isn’t refrigerated for a few months, it will continue to ferment, causing the yeast to convert the sugar into higher quantities of alcohol.’