


What Is Kombucha Tea?

Fact Checked

kombucha teas

Story at-a-glance -

  • Kombucha is made by fermenting sugared black or green tea with yeast and acetic acid bacteria, producing a fizzy beverage with a sour and acidic flavor
  • The bioactive microorganisms in kombucha are the sources of its benefits. There are studies highlighting the antimicrobial properties of this beverage, which also suggest its potential to influence human gastrointestinal microflora
  • A study published in 2011 studied the antibacterial and antifungal activities of kombucha made from green and black teas, and the results exhibited their antimicrobial potential against Candida species, except for Candida krusei
  • There are some side effects linked to improperly prepared homemade kombucha, such as infection, allergic reactions and upset stomach. I advise you to thoroughly do your research and acquire all the correct equipment before attempting to make your own kombucha

An increasing number of people have been striving for a healthier lifestyle in recent years. As a result, there's been a surge in the demand for health-boosting beverages. One of the most interesting (and at times controversial) beverages out there is kombucha.

Sometimes called "combucha,"1 or "kombucha tea," the market for this carbonated (but potentially alcoholic) beverage is said to be growing by 25 percent every year.2 According to a report from MarketsandMarkets, from 0.6 billion dollars in 2015, the global kombucha market is estimated to grow to 1.8 billion dollars by 2020.3

But what exactly is kombucha, and why can it offer potential benefits, despite having alcohol content? Discover more about this beverage by reading this article.

Basic Facts About Kombucha

The most basic definition of kombucha is "fermented sweet tea."4 It's made by fermenting sugared black or green tea5 with yeast and acetic acid bacteria.6 The fermentation process can take one to two weeks,7 and the end product is a fizzy beverage with a sour and acidic flavor.8

To make kombucha, scoby is needed: This stands for a "symbiotic culture of bacteria and yeast."9 The scoby appears as a rubbery, disk-shaped blob that forms a new layer and thickens with every batch.10 It may seem unappetizing, but the appearance of the scoby is a sign that the microorganisms in the beverage are hard at work.11

When the fermentation process occurs, the sugar in the tea is broken down by the scoby and releases probiotic bacteria. Fermentation is also responsible for the fizzy nature of the drink,12 as well as its slight alcohol content.13

There are numerous accounts of how kombucha came to be. Some say it was made for Emperor Qin Shi Huangdi during the Qin dynasty, while he was looking for an elixir to help him achieve immortality. Others credit the discovery to a Korean doctor named Kombu-ha-chimu-kamu-ki-mu, who produced the beverage for Inyoko, a Japanese emperor who was dying due to an unknown illness. The good doctor supposedly prescribed this tonic and healed the emperor.14

These are just two theories on the origin of this beverage, but whichever of them may be true, one thing is for certain: Kombucha has been appreciated by humankind for a very long time.

The Four Major Health Benefits Of Kombucha Tea

Many people remain doubtful over whether kombucha is good for you, mainly due to the possibility that it can possess a level of alcohol comparable to beer or wine. What sets kombucha apart is that its alcohol is self-limiting, unlike beer and wine which are intentionally brewed to have higher alcohol level.15 Hence, drinking kombucha that has very low alcohol content could potentially let you reap health benefits.

So what is kombucha good for, and why can it potentially deliver positive effects? You can thank the bioactive microorganisms in the drink for these benefits. According to a study published in the Journal of Food:16

"The beneficial effects of kombucha are attributed to the presence of bioactive compounds that act synergistically. Bacteria contained in kombucha beverage belongs to the genus Acetobacter, Gluconobacter, and the yeasts of the genus Saccharomyces along with glucuronic acid, contribute to health protection."

Below are four potential benefits that kombucha tea may have for your health:

Helps eliminate pathogenic microorganisms, including Candida — A study published in 2011 examined the antibacterial and antifungal activities of kombucha made from green and black teas, and the results exhibited their antimicrobial potential against Candida species, except for Candida krusei. The highest antimicrobial potential was also seen in green fermented tea.17

May contribute to optimal gut microflora — A 2014 study identified some of the bacterial and fungal populations in kombucha, and these include Gluconacetobacter, Acetobacter and a prominent Lactobacillus population.18 There are studies highlighting the antimicrobial properties of this beverage,19 which also suggest its potential to influence human gastrointestinal microflora.20

May have liver-protective effects — Studies conducted on rats found that kombucha tea may have hepatoprotective properties and may help revert liver toxicity.21 A 2003 study published in Biomedical and Environmental Sciences found that its immunomodulating and antioxidant properties may help against lead-induced oxidative stress.22

May help protect against prostate cancer — A study published in Biomedicine and Preventive Nutrition found that kombucha may have protective effects against prostate cancer cells. The researchers noted:23

"Our study demonstrates that kombucha significantly decreases the survival of prostate cancer cells by downregulating the expression of angiogenesis stimulators. These findings suggest that kombucha may be useful for the prostate cancer treatment/prevention."


Does Kombucha Have Caffeine?

Because kombucha is made from black or green tea, you should expect it to have some degree of caffeine in it. According to Bon Appetit, the fermentation process reduces the caffeine content, but about a third remains in the beverage.24 The levels can vary among different kombucha brews. If you're caffeine sensitive, you may want to skip or moderate your consumption of this drink, to avoid the side effects of caffeine.

Watch Out for These Kombucha Tea Side Effects

While there are manufacturers of high-quality kombucha out there, some people are curious as to how this beverage is produced so that they can make it at home. While the process is fairly easy, you should be careful, as there are some side effects linked to improperly prepared homemade kombucha.

One issue is the potential alcohol content. The Spruce Eats notes that it might cause a moderate "buzz" — however, this depends on the sensitivity that the individual has to alcohol. Women are said to be more sensitive than men, as well as people with lower body mass.

Another concern is the potential for bacterial contamination. If your kombucha becomes contaminated with bad bacteria, you may experience side effects such as an infection, allergic reaction or upset stomach.25 Anthrax and aspergillus (a fungus that is harmful to immunocompromised individuals) have also been reported to contaminate kombucha brews.26 In Iran, an outbreak of cutaneous anthrax infection had been reported due to kombucha tea.27

Another kombucha tea danger is the risk of lead poisoning, which can occur when ceramic containers are used for brewing. This happened to a woman in Wales, who was taken to the hospital after showing symptoms of lead poisoning. It turned out that the kombucha she was brewing in a ceramic pot caused lead to leach from the glaze, poisoning her.28

For this reason, you should always use a glass container when fermenting kombucha.29 Usually, you can be alerted by contamination when your kombucha has an strange odor and flavor, but these factors may not always present themselves.

How to Make Kombucha Tea

I advise you to thoroughly do your research and acquire all of the correct equipment before attempting to make your own kombucha. As long as the proper measures are taken, kombucha is a healthy drink that you can brew. If want to try making kombucha tea, here's a procedure from The Kitchn you can try:30

Kombucha Tea Recipe


3 1/2 quarts water

1 cup sugar (regular granulated sugar works best)

8 bags black tea, green tea or a mix (or 2 tablespoons loose leaf tea)

2 cups starter tea from last batch of kombucha or store-bought kombucha (unpasteurized, neutral-flavored)

1 scoby per fermentation jar, (you can make this at home31 or purchase it online)

Optional flavoring extras for bottling:

1 to 2 cups chopped fruit

2 to 3 cups fruit juice

1 to 2 tablespoons flavored tea (like hibiscus or Earl Grey)

1/4 cup honey

2 to 4 tablespoons fresh herbs or spices


Stock pot

1-gallon glass jar or two 2-quart glass jars

Tightly woven cloth (like clean napkins or tea towels), coffee filters or paper towels, to cover the jar

Bottles: Six 16-oz glass bottles with plastic lids, swing-top bottles or clean soda bottles

Small funnel


1. Bring the water to a boil, and then remove from heat. Stir in the sugar to dissolve. Drop in the tea bags or loose leaf tea and let steep until the water has cooled. This may take a few hours, depending on the size of your pot. To speed up the cooling process, place the pot in an ice bath.

2. Once the tea has cooled, take out the tea bags or strain out the loose tea. Add in the starter tea. This turns the liquid acidic, preventing bad bacteria from forming during the first few days of fermentation.

3. Pour the mixture into a 1-gallon glass jar (or divide between two 2-quart jars — if you do this, though, you will need two scobys). Slide the scoby into the jar gently, with clean hands.

4. Cover the mouth of the jar with a few layers of tightly-woven cloth, coffee filters or paper towels and secure with a rubber band.

5. Let the mixture ferment for seven to 10 days. Make sure the jar is at room temperature, and not under direct sunlight. Place it where it won't be disturbed. Make sure to check the kombucha and the scoby periodically. It might float to the top, bottom or the side during fermentation, and a new layer will form on the surface after a few days.

6. If you see brown string-like bits under the scoby, or if sediment is forming at the bottom, don't be alarmed — this is normal. Bubbles forming around the scoby are also normal.

7. After seven days, try tasting the kombucha, pouring a small amount into a cup. Once it reaches your desired tartness and sweetness, you can bottle the kombucha.

8. Take out the scoby. But before doing so, prepare and let cool another pot of strong tea for your next batch. Gently lift the scoby out of the kombucha and place on a clean plate. If the bottom layer of the scoby is getting very thick, remove it.

9. Bottle the finished kombucha. Measure out a starter tea from this batch of kombucha and set aside for your next batch. Pour the kombucha into bottles (you can strain it if you like) using the small funnel. Add any juice, herbs or fruit for flavoring, but make sure to leave about a half inch of head room in each bottle.

An alternative option is to infuse the kombucha with your desired flavoring for a day or two in another covered jar before straining and bottling. This will produce a "cleaner" kombucha.

10. Place the bottled kombucha at room temperature out of direct sunlight and leave for one to three days so it will carbonate. The kombucha is carbonated when the bottles feel rock solid. Refrigerate to stop fermentation and carbonation. Make sure to consume your kombucha within a month.

Note: Avoid prolonged contact between the kombucha and metal both during and after brewing. This can affect the flavor of your kombucha and weaken the scoby over time.

This recipe makes about 1 gallon of kombucha tea.

Can You Drink Kombucha While Pregnant?

Many probiotic-rich foods are great for pregnant moms, but kombucha may not be one of them. There's a lot of debate on whether drinking kombucha during pregnancy is OK or not, and studies on this area are still lacking. But due to this beverage's potential to harbor bad bacteria and produce small amounts of alcohol, I would advise you to err on the side of caution and avoid drinking it during this delicate period.

Remember that any amount of alcohol during pregnancy can be harmful. The U.S. Centers for Disease Control and Prevention (CDC) notes that ingesting alcohol can lead to fetal alcohol spectrum disorders (FASDs) — these are "physical, behavioral, and intellectual disabilities that last a lifetime."32 Hence, opt for other safer probiotic foods during pregnancy. I would recommend drinking kefir, or fermented milk, instead of kombucha during pregnancy.

Frequently Asked Questions (FAQs) About Kombucha

Q: What is kombucha tea made from?

A: Kombucha is a fermented sweetened tea, and is made by fermenting black or green tea with yeast and acetic acid bacteria. A scoby — a symbiotic culture of bacteria and yeast — is also used to ferment the drink.

Q: What does kombucha tea taste like?

A: Kombucha tea is a carbonated drink with a sour and acidic flavor.

Q: How much alcohol is in kombucha?

A: This depends on the manufacturer and the brewing method. By law, the kombucha brands sold in the market cannot have more than 0.5 percent alcohol, or else they would have to state it on the label to comply with the Alcohol and Tobacco Tax and Trade Bureau (TTB) regulations.33,34

Q: Can homemade kombucha be dangerous?

A: If produced in unsanitary conditions, homemade kombucha brews may become contaminated with pathogenic bacteria and mold, which can cause side effects. Another danger with homemade brews is the potential for lead poisoning, particularly when brewed in ceramic containers. Hence, use only glass jars when brewing this beverage.

+ Sources and References