What is kombucha? Benefits & side effects

Kombucha is a fermented tea drink with an acidic flavour and slight fizz.

As kombucha has a low calorie and sugar content, it's an excellent choice for consumers looking for an alternative to water without any bad-for-you ingredients.1

But what is kombucha, and why is it so popular?

In this article, we'll tell you everything you need to know about kombucha. From its benefits and potential side effects to whether or not you should be drinking it, so you can learn whether you can safely include a kombucha drink in your diet.

But first, let's talk briefly about the benefits of kombucha and why we're seeing this fermented fizz everywhere, from health food shops to the mixer shelves in hipster bars.

What is kombucha? 

Kombucha is a fermented drink made from tea, sugar and a bacterial culture called a SCOBY (symbiotic colony of bacteria and yeast).
The fermentation process takes between 7 to 14 days.
Both green and black teas are used to produce kombucha. However, homebrewers generally use black tea, as it ferments faster.
Black tea varieties typically have a deeper flavour. In contrast, some drinkers love green tea kombucha because it has a more delicate flavour and an almost grassy quality.

What does kombucha taste like?

Kombucha is a mildly fizzy, fermented cold tea drink with a slightly sour flavour that can be made in various flavours, from refreshing raspberry to ginger and lemon.
The origins of the drink are estimated to go back as far as 2000 years.2
But its soaring popularity in recent years in the UK is likely to be down to rising interest in the role of fermented foods in gut health. This has led to pre-bottled versions of this ancient brew becoming more widely available.


Why is kombucha popular?

Fermented drinks have grown in popularity over the past decade as emerging science highlights their benefits.3

In fact, The world consumed over 18-kilo tonnes of fermented beverages in 2018!4

What is kombucha good for? 5 benefits

Kombucha has been linked to a whole host of benefits, These are just some of the benefits of kombucha and how it can support you in your healthy lifestyle:

  1. Source of probiotics

Thanks to its bacteria content, kombucha tea may help to maintain a healthy population of microorganisms in your gut. These bacteria can benefit your stomach and, in turn, your overall wellness.6

Fermented foods are made from bacterial cultures which produce probiotics during fermentation, and kombucha is no exception.

Although probiotic content is linked to digestive health, no current evidence proves kombucha provides effective probiotics for health.7,8

  1. Antioxidant content

Both green and black tea contains antioxidants called polyphenols, which have been linked to cardiovascular health.9

Although studies show kombucha's fermentation process enhances tea's antioxidant properties, there's no conclusive evidence which proves kombucha's polyphenol content positively impacts health.10

  1. Vitamin and mineral content

Kombucha contains essential vitamins and minerals for your overall health and well-being. This includes zinc, copper, magnesium, iron, nickel, and cobalt, as well as vitamins B1, B6, B12 and Vitamin C.11

  1. It's a great alternative to less healthy beverages

In today's age, people are choosing kombucha instead of high-calorie, carbonated, sugar-sweetened beverages or alcohol.

  1. It may have antibacterial properties

In particular, kombucha made from green tea has been shown to possess microbial properties.

Specifically, green tea-based kombucha was found to inhibit Staphylococcus epidermidis, Listeria monocytogenes and Micrococcus luteus.

Not only this, but it may also have anti-Candida potential against infection-causing bacteria and Candida yeasts.13

How to make kombucha

The popularity of this fizzy, fermented tea is showing no signs of slowing down. Of course, many pre-bottled options are available, but have you considered brewing your own?

If you are ready to test the benefits of kombucha or fancy a mini microbiology project of your own, you can follow a simple 7-step kombucha recipe to create your own fermented kombucha drink brimming with friendly bacteria.14

What is in kombucha?

Brewing kombucha is easy with the right know-how and ingredients! Kombucha is usually made using five core ingredients. Here is what you'll need to make 1 litre of the drink.

  1. 1 litre of cold water: Filter out chlorine first by boiling and allowing it to cool
  2. 1 bag (or loose tea equivalent) of tea: Black or green tea both work
  3. 50-100g of sugar: Cane sugar is typically used, with the exact amount to suit your tastebuds
  4. 1 small kombucha SCOBY: a SCOBY (symbiotic culture of bacteria and yeast) is a disk-shaped culture that creates fizz during fermentation. It is sometimes also known as a "kombucha mushroom" or "kombucha mother".
  5. 100ml of a starter tea: This is kombucha reserved from a previous batch to kickstart your new brew. Your SCOBY should come sitting in this liquid.

What else you'll need

  • A large glass jar (clear so you can see what's happening.)

A quick word of advice, be careful to keep everything clean, and if there is any sign of mould in your mixture, discard it.

  1. Put on a brew

Steep the tea and sugar in 250ml of boiled water and leave to cool for 6-10 minutes.

  1. Create the right environment for the SCOBY

Remove the tea bag (try not to squeeze it) and add the remaining 750ml of cold de-chlorinated water.

  1. Add the SCOBY and the starter tea

To allow for SCOBY growth and other fermentation effects, make sure to leave at least 5cm of space at the top.

  1. Cover the liquid

Use a cloth, paper towel, and elastic band to prevent dust and fruit flies from getting in. But don't seal the jar as the SCOBY needs to breathe.

  1. Leave for 6-9 days

The ideal temperature range for fermentation is 26-27°C. But room temperature should be fine if it's above 21°C.

It's better to leave your fermenting kombucha out of a cupboard but avoid direct sunlight.

  1. Start sampling

The exact point when your kombucha is ready depends on your personal taste preference. Some people find it's still too sweet after six days and prefer to wait until nine or 12 days before drinking.

  1. Or you could move on to a secondary fermentation

If you want to add flavours to your brew, if you prefer a higher level of carbonation or are looking to make hard kombucha, you can ferment further.


What is hard kombucha?

Whilst fermentation means that all types of kombucha will contain alcohol, hard kombucha is specifically created to have more significant amounts of alcohol.15

The fermentation process used to brew traditional kombucha is repeated to create hard kombucha, with more sugar and yeast added to make it stronger.

Sometimes, hard kombucha, or alcoholic kombucha, can contain up to 4-7% ABV. In contrast, a non-alcoholic kombucha will hold up to 0.5% ABV, the equivalent of a non-alcoholic beer.15 So, it's worth checking the label on your kombucha to ensure you're drinking the right type!

Fancy making your own alcoholic kombucha? Follow our step-by-step guide to making hard kombucha, and learn more about hard kombucha. You can even add it to your favourite cocktail for a delicious twist.

Are there side effects of drinking kombucha?

Some unpleasant side effects and potential dangers are sometimes associated with drinking too much kombucha.16


These include:

  • Stomach pain
  • Allergic reaction
  • Diarrhoea
  • Nausea
  • Dizziness
  • Headache16


However, scientific studies show that most people who experienced side effects either had a pre-existing illness or drank a contaminated batch of kombucha.17,18

Like with any live food or drink, it's advised to allow your digestive system to adjust by gradually increasing the amount you drink. For example, start with 100ml daily for the first week and increase slowly as it might not suit everyone.


People with gastric and kidney complaints are more likely to experience an upset stomach from drinking kombucha than those who don't.19

In addition, if you have a weakened immune system, kombucha may not suit you, so you should ask your GP before introducing it into your diet.


Can you drink kombucha whilst pregnant or breastfeeding?

Whilst kombucha is full of great vitamins, minerals, and healthy bacteria, there are a few things to keep in mind if you are pregnant or breastfeeding.

  • All kombucha contains alcohol

The fermentation process used to make kombucha naturally produces alcohol.

Generally, the alcoholic content in kombucha is around 0.5%, often similar to non-alcoholic beer and usually considered safe for pregnant women.20 Any less than 0.5%, and it is considered non-alcoholic.

Still, it is unknown whether even this tiny amount will affect your baby. So, if you are pregnant or breastfeeding, always check with your doctor to ensure you are safe for yourself and your baby.

  • It can be unpasteurised

Pasteurisation is the process of heating products to kill harmful bacteria.

In its purest form, kombucha is unpasteurised, so there is a risk of it containing some harmful bacteria.

During pregnancy, it is often recommended to avoid unpasteurised products to reduce the risk of ingesting harmful bacteria.21

  • It contains caffeine

As kombucha is made using green or black tea, it contains caffeine. The amount of caffeine found in kombucha can vary, but it should be something to keep in mind.

During pregnancy, your body takes longer to process caffeine.22

While most studies show that a moderate amount of caffeine is safe for you and your baby, others show that increased caffeine has some dangers.23

So, it is recommended that you limit your caffeine consumption during pregnancy.

While breastfeeding, a small percentage of caffeine will end up in your breast milk. If you drink large amounts of caffeine while breastfeeding, your baby might become irritable and struggle with sleep.24

So, it's best to wait a while after drinking kombucha before breastfeeding. 

Can kombucha help you control weight?

Kombucha may be able to help you control weight. This is because kombucha contains polyphenols: micronutrients that we get from plant-based foods.25

One study from 2010 concluded that foods or drinks containing polyphenols might facilitate weight loss and prevent weight gain.26

These micronutrients act as antioxidants to help aid recovery after exercise, support your body in burning fat and help you to manage your blood sugar levels.27

So, choosing foods rich in polyphenols could be beneficial when it comes to weight loss.

Should you drink kombucha every day?

While the benefits of drinking kombucha tea are great, that isn't a green light for consuming too much of it. The Centres for Diseases Control state that 115ml of kombucha, up to three times a day, is safe to drink.28

If you have any queries about whether you should have kombucha at all, always check with a medical professional, as they will be able to advise you further. 

Are there side effects of drinking kombucha?

Some unpleasant side effects are sometimes associated with drinking too much kombucha.15

These include:

  • Stomach pain
  • Allergic reaction
  • Nausea
  • Dizziness
  • Headache16

However, scientific studies show the majority of sufferers either had a pre-existing illness or drank a contaminated batch of kombucha.17,18

Like with any live food or drink, it’s advised to allow your digestive system to adjust by building up the amount you drink gradually.

For example, start with 100ml a day for the first week and increase slowly. Also, it might not suit everyone.

Finally, if you’re pregnant, breastfeeding or have a compromised immune system, kombucha may not be suitable for you so ask your GP before introducing it into your diet.

Who should avoid kombucha?

People with gastric and kidney complaints are more likely to suffer an upset stomach from drinking kombucha than non-sufferers.19

Pregnant women may choose to avoid kombucha because of the alcohol content. However, it’s thought to be too low a concentration to affect a foetus.

The final say

Kombucha has multiple potential benefits due to its antioxidant contents.

But it's worth noting that studies on the effects of kombucha are limited, so none of the benefits are 100% confirmed.

Both shop-bought and homemade kombucha are tasty drinks, so why not give one a try?

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