Is kombucha tea healthy, what are the potential side effects, and what is a 'scoby'? We explore the science behind this fermented fizzy drink.
Fermented food has soared in popularity in recent years, in part thanks to the ever increasing interest and research into gut health. Kombucha, a mildly fizzy, slightly sour drink, has become popular with health conscious consumers looking for an alternative to processed fizzy drinks that are often packed with sugar or artificial sweeteners. But is kombucha really good for you, or does it fall short of the media hype? We take a closer look at the potential benefits and side effects of this beverage.
What is kombucha?
Kombucha is a fermented drink made from sweetened tea and a specific culture known as a scoby. Scoby stands for ‘symbiotic culture of bacteria and yeasts’. The bacteria and yeasts convert the sugar into ethanol and acetic acid. The acetic acid is what gives kombucha its distinctive sour taste.
How do you make kombucha?
Kombucha is usually made using:
- Cold filtered water
- Black/green tea (bags or loose leaf)
- Scoby – purchased online, or from an existing batch of kombucha
To make kombucha, the tea and sugar is steeped in boiled water and left to cool before adding the scoby. This is covered and left to ferment for up to a week. The mixture is then poured into an airtight container with some extra sugar and left for a few more days – the longer it is left, the fizzier it will become. At this point, flavourings such as spices or fruit can be added.
Read more about how to make kombucha.
Is kombucha a good source of probiotics?
Fermented foods such as yogurts, sauerkraut and kefir all contain live microorganisms. As kombucha is the product of fermentation, a number of probiotic bacteria are produced. At specific concentrations, probiotic bacteria can help to balance the gut microbiome in humans and improve digestion. However, to date, there have not been enough studies to confirm whether kombucha contains enough beneficial bacteria to be deemed an effective probiotic.
Is kombucha high in antioxidants?
Antioxidants are substances that protect the body from oxidative damage caused by free radicals. Free radicals are a normal by-product of processes in the body, but the key is to minimise their impact by having a diet rich in antioxidants. Tea, especially green tea, is rich in a group of antioxidants called polyphenols. It is suggested that the fermentation time has an impact on the antioxidant properties of kombucha, however, to date there is little evidence to suggest a significant benefit to human health.
Does kombucha contain vitamins and minerals?
Kombucha contains small amounts of vitamins and minerals which are produced when the yeast breaks down the sugars, including vitamin C and B vitamins B1, B6 and B12.
Can kombucha help with weight loss and improve gut health?
Although kombucha is claimed to be beneficial for several ailments relating to digestion, weight loss, bone health and inflammation, there is almost no clinical evidence available to prove the claims. Most of these claims are either anecdotal or have come from animal studies.
Additionally, the evidence is insubstantial as to whether the beneficial bacteria (probiotics) found in kombucha can survive the acidic environment of the stomach to then have an impact on health.
Are there side effects of drinking kombucha?
Kombucha is classified as a functional food because of its potentially beneficial effect on health as part of a varied and balanced diet, however there are some risks. Kombucha is not advised for pregnant or breastfeeding women, or those who have a compromised immune system. It is important to reiterate, there haven’t been many human clinical studies to prove its safety and efficacy. There have been some reports that drinking too much kombucha can lead to unpleasant side effects such as stomach ache, nausea and dizziness. Prolonged fermentation is not recommended because of the accumulation of organic acids, which might reach harmful levels for direct consumption. Always see your GP if you are concerned about introducing kombucha into your diet, or if you have any adverse side effects after consuming it.
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This article was reviewed on 12th February 2019 by dietitian Emer Delaney.
Emer Delaney BSc (Hons), RD has an honours degree in Human Nutrition and Dietetics from the University of Ulster. She has worked as a dietitian in some of London's top teaching hospitals and is currently based in Chelsea.
Jo Lewin works as a Community Nutritionist and private consultant. She is a Registered Nutritionist (Public Health) registered with the UKVRN. Visit her website at www.nutrijo.co.uk or follow her on Twitter @nutri_jo.
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