Kombucha: benefits, home brewing and complete guide to the fermented drink

Kombucha fascinates, seduces and occasionally unsettles. This fermented drink made from tea and sugar has been cherished across Asia for centuries, and has surged in popularity in France over the past decade. Benefits for digestion, the gut microbiome and antioxidant intake: what does the science actually say? How do you brew kombucha at home? What recipe should a beginner follow? This is your complete guide to the world's most talked-about probiotic drink.

What is kombucha?

Kombucha is a fermented drink made from sweetened tea (typically green tea or black tea) fermented by a symbiotic culture of bacteria and yeast known as a SCOBY (Symbiotic Culture Of Bacteria and Yeast), sometimes called the kombucha mother. The fermentation process lasts 7 to 21 days and converts the sugar into organic acids, carbon dioxide and naturally occurring probiotics.

The finished drink is lightly sparkling, pleasantly tart and refreshing, with very little residual sugar and a wealth of bioactive compounds. Its amber colour and distinctive flavour make it a genuinely appealing alternative to mass-produced soft drinks.

The origins and history of kombucha

The precise origins of kombucha remain a matter of debate. Most accounts place its first appearance in northern China or Manchuria over 2,000 years ago, during the Tsin dynasty. From there, kombucha is said to have reached Japan around 415 AD, before travelling to Russia in the 19th century, where it became a popular everyday drink known as tea kvass.

Its arrival in the West came later: it gained a following in the United States during the 1990s, and began appearing in France from around 2010 onwards. The growing enthusiasm for home fermentation and gut health has since accelerated its rise considerably.

The benefits of kombucha

Probiotics and the gut microbiome

Kombucha contains lactic acid bacteria (including Lactobacillus and Acetobacter) and beneficial yeasts that support the gut microbiome. Preliminary studies, conducted in vitro and on animals, suggest a positive effect on intestinal flora comparable to that of other fermented foods such as kefir, yoghurt and sauerkraut. Human clinical trials remain limited but encouraging.

Antioxidants

Because it is brewed from green tea or black tea, kombucha retains much of the polyphenols and catechins present in the original tea. Fermentation may even enhance the bioavailability of certain antioxidants. A protective effect against oxidative stress has been documented in in vitro studies.

Organic acids and natural detoxification

Fermentation produces glucuronic acid (with a theoretical hepatic benefit), acetic acid and gluconic acid. These compounds are thought to support the liver's natural detoxification processes, according to several animal studies. Human evidence is still lacking.

Hydration and a smarter alternative to soft drinks

With low residual sugar (1 to 5g per 100ml depending on fermentation time), a lightly sparkling texture and a pleasantly tart flavour, kombucha is an excellent everyday alternative to industrial soft drinks. It delivers real sensory pleasure without the sugar load, making it a thoughtful choice for anyone watching their daily intake.

Home kombucha recipe: step by step

Equipment you will need

• A 2 to 3 litre glass jar (never metal).
• A clean cloth and an elastic band.
• A kitchen thermometer.
• Thick glass bottles for the second fermentation.
• A kombucha mother (SCOBY) plus 100 to 200 ml of starter liquid (already fermented kombucha).

Ingredients (makes 1.5 litres)

• 1.5 litres of filtered, unchlorinated water
• 120g of organic white sugar (essential for the bacteria)
• 8 to 10g of green tea or black tea (unflavoured only for the first fermentation)
• 1 SCOBY plus 200 ml of starter liquid

Step 1: brew the sweetened tea

Bring the water to the boil, dissolve the sugar in it, then add the tea. Leave to steep for 10 to 15 minutes, then strain. Allow to cool fully to room temperature (no warmer than 25 to 30°C). Never pour the liquid over the SCOBY while it is still warm: heat kills the bacteria.

Step 2: first fermentation (7 to 14 days)

Pour the cooled sweetened tea into the jar, add the starter liquid, then gently place the SCOBY on the surface. Cover with a cloth (never an airtight lid). Keep away from direct light at an ideal temperature of 20 to 25°C.

Begin tasting from day 7. If it still tastes sweet, leave it a little longer. Once it has a pleasantly tart, lightly sparkling quality (typically around day 10 to 14), move on to step 3.

Step 3: second fermentation (2 to 5 days)

Strain the kombucha. Set aside 200 ml as your new starter and keep the SCOBY (rinse it gently). Fill your thick glass bottles, leaving about 4 cm of headspace. Add flavourings if you wish: fresh fruit, juice, ginger, herbs such as basil or mint.

Seal tightly and leave for 2 to 5 days at room temperature. This stage builds the carbon dioxide that creates the fizz. Refrigerate afterwards to halt fermentation.

How to drink kombucha

Kombucha is best served chilled, starting with 100 to 250 ml per day. Increase gradually as your body adjusts. It is ideal between meals to make the most of its probiotic effect, or alongside a light lunch.

A word of caution: those new to fermented foods, or with sensitive digestion, should start with as little as 50 ml. Too much too soon can cause bloating or mild digestive discomfort in the first few days.

Precautions and contraindications

Natural as it is, kombucha does call for a few precautions:

• Pregnant and breastfeeding women: avoid (residual alcohol content and microbiological risk).
• Children under 6 years of age: not recommended.
• Immunocompromised individuals: medical advice is essential.
• Those on antidiabetic medication: monitor blood sugar levels (residual sugar present).
• Diabetes: limit consumption.

Kombucha contains a small amount of naturally occurring alcohol (0.5 to 2%), a by-product of fermentation. Negligible for most adults, but worth bearing in mind for anyone with a history of alcohol dependency.

Buying kombucha vs. brewing it at home

Ready-to-drink kombucha is now widely available in shops, typically priced between 3 and 6 euros per bottle. Convenient, but the cost adds up. Brewing at home brings the price down to around 30 cents per litre once you have your SCOBY, making it a very practical choice for regular drinkers.

Our shop offers a carefully chosen selection of green and black teas well suited to brewing kombucha: organic green teas and organic black teas. Always choose plain, unflavoured teas for the first fermentation.

Flavouring variations

Once you have the basics down, the second fermentation opens up a world of possibilities:

• Fresh ginger and lemon (the classic combination)
• Raspberry and mint
• Strawberry and basil
• Dried hibiscus and cardamom
• Apple and cinnamon
• Blackcurrant and lavender

Allow 50 to 100g of fresh fruit or 1 tablespoon of dried herbs per 500 ml bottle.

Frequently asked questions

Is kombucha actually good for you?

Clinical evidence remains limited but consistent: a likely probiotic effect, a good antioxidant profile and low sugar content. No food is a miracle cure, but kombucha is a genuinely healthy drink when enjoyed as part of a balanced diet.

How long does home-brewed kombucha keep?

Up to 1 to 2 months in the refrigerator. Fermentation continues slowly even at cold temperatures. Bottles can become dangerously pressurised if left too long or kept somewhere warm: never leave them at room temperature after bottling.

Does kombucha contain alcohol?

Yes, between 0.5 and 2% depending on fermentation time. In France, it is legally classified as non-alcoholic (below 1.2%) provided fermentation is stopped in time. Worth keeping in mind for children and drivers.

Where can you buy a SCOBY?

Health food shops, specialist online retailers (such as Symbiose or Carrefour Bio), or through word of mouth from fellow home brewers. A quality SCOBY with starter liquid typically costs between 10 and 20 euros.

My kombucha isn't fizzy. What went wrong?

The second fermentation was likely too short, or the bottles were not fully airtight. Try leaving them for an additional 2 to 3 days, keeping an eye on the pressure buildup.

Can you use any tea?

Stick to plain green tea or black tea. Avoid flavoured teas, as the essential oils they contain can disrupt the bacteria, and avoid herbal infusions, which lack the tannins the SCOBY needs to thrive.