Kombucha 101: Nutrition, Health Benefits, Side Effects, and More

There’s been lots of buzz about kombucha, but the drink isn’t new. The fermented tea first became popular in East Asia for its health benefits, and it originated in northeast China around 220 B.C. The name “kombucha” comes from Dr. Kombu, who was a Korean doctor who introduced the drink in Japan in 414 A.D. as a cure for Emperor Inkyo’s digestive issues.

Trade routes eventually spread kombucha to Russia and Eastern Europe. During the 1950s and ’60s, the drink was especially popular in Germany, France, and Italy after researchers in Switzerland reported it had similar health benefits to eating yogurt. (1)

Kombucha first became commercially available in the United States in 1995, notes the Colorado School of Public Health. (2) Today, you can find kombucha online and at many major grocery stores. It’s also possible to buy fermenting cultures and make your own at home.

But there’s still a bit of debate about whether kombucha lives up to its hype. Some people are firm believers in the drink’s healing abilities, while others warn of potential unpleasant side effects, notes the Mayo Clinic. (3) Read on to learn more about kombucha.

What Is Kombucha?

Kombucha is a fermented beverage made when a symbiotic culture of bacteria and yeast (SCOBY) is added to a mixture of green or black tea and sugar. You may have heard it called a kombucha mushroom because the yeast culture looks like a mushroom cap, notes Kombucha Brewers International. (4) But it’s actually a colony of bacteria and yeast, not a mushroom. (3)

How Is Kombucha Made?

The tea is boiled in hot water and then allowed to steep. After the tea bags or leaves are removed, sugar is added while the water is still hot. (2) When the mixture cools, the culture, or SCOBY, is added. Then the batch is covered and left to ferment at room temperature for around a week. Larger batches, like those made by commercial kombucha manufacturers, may be left to ferment for as long as 30 days because of their size.

During the fermentation process, alcohol, various types of acid (including gluconic, acetic, and lactic), carbon dioxide, probiotics, and other nutrients multiply from the SCOBY. The carbon dioxide gives the drink its fizz, and the probiotic bacteria may provide health benefits, noted a 2019 study. (5)

The final result is a drink that tastes tart, sort of like a slightly sweet apple cider vinegar, and has some carbonation.

The nutrients in kombucha can vary depending on the brand and the fermentation process. They each have live bacteria and yeast, antioxidants, probiotics, B vitamins, and minerals. (2) Researchers still don’t understand the complete chemical content of the drink and its potential functions because it’s so complex, according to a 2018 article. (6)

In general, an 8-ounce (oz) serving of unflavored kombucha has around 30 calories and 2 to 3 grams (g) of sugar. (2) But servings can have between 25 and 90 calories and up to 8 g of sugar depending on how they are prepared, according to the U.S. Department of Agriculture (USDA). (7) Sugar content can be higher in flavor blends where fruit juices are added, notes My Fitness Pal. (8)

Also know that kombucha may contain alcohol, depending on the product. To be considered nonalcoholic and labeled as such, kombucha must contain less than 0.5 percent alcohol.

The brands you typically buy at the grocery store are nonalcoholic and regulated by the U.S. Food and Drug Administration (FDA). But because they still have a very small amount of alcohol, you’ll see that warning on the label.

All that said, there isn’t enough alcohol in most store-bought kombucha to make you feel any different — unless you’re drinking hard kombucha, that is. Hard kombucha has increased in popularity over the past few years, and there are now many brands and flavors to choose from. Some hard kombuchas have about as much alcohol as a light beer, but those varieties are made differently, notes the Alcohol and Tobacco Tax and Trade Bureau. (9)

Kombucha also contains caffeine. The amount depends on how long the tea steeps and what type of tea you use. According to Mayo Clinic, there are about 28 milligrams (mg) per 8-oz serving of brewed green tea and 47 mg for brewed black tea. (10) Kombucha will likely have even less.

There have been many health claims about kombucha. Russian studies at the beginning of the century suggested the drink could prevent cancer and heart disease, reduce inflammation, and improve the immune and digestive systems. (11) It’s also been said to boost energy levels, help with constipation, and balance the body’s pH. But researchers still don’t know enough about kombucha’s effect on humans, so most recommend using it with caution.

Scientists do know that some of the substances found in kombucha, like probiotics and antioxidants, have proven health benefits. Probiotics are microorganisms that develop during the fermentation process. Lactobacillus, a probiotic bacteria in yogurt, is also found in kombucha and may improve digestion and reduce inflammation. (12) Green tea is loaded with antioxidants, which help the body protect itself from substances that could damage cells, so kombucha made with green tea may have some ability to prevent disease. (10)

In fact, a 2019 review noted that green tea may play a role in stimulating the body’s natural cellular cleaning processes, called autophagy, and help protect the body against oxidative stress. (13) Oxidative stress is associated with cancers, heart disease, and stroke.

The review authors also note that green tea could help protect the skin from harmful UVA rays, which contribute to wrinkles and other signs of aging.

What’s more, certain compounds in green tea called catechins could offer neuroprotective effects, potentially helping keep Alzheimer’s disease at bay.

Kombucha itself has the potential to kill off bad bacteria. When it’s made from green or black tea, the drink develops antibacterial properties during the fermentation process. A 2019 study found that certain preparations of kombucha were able to fight off some types of infection-causing bacteria. (14)

While kombucha is not a miracle elixir, the USDA’s MyPlate guidelines note that it can still be part of a healthy diet. Because it has a lot less sugar than soda, the drink offers something different for those who want to enjoy something carbonated while watching their sugar intake.

Learn More About Kombucha Benefits

Kombucha bought at the store is generally considered safe, but it’s possible to have an unpleasant reaction to it. Some reported side effects include upset stomach, infections, and allergic reactions, past research noted. (3,15)

Severe reactions are rare but can happen. One report described a 22-year-old man who experienced lactic acidosis (when the body has trouble processing lactic acid, causing blood pH to drop) and liver failure after drinking kombucha tea. (16) Nonetheless, this is not a typical reaction, and it’s important to note that this subject was HIV-positive and immunocompromised.

Learn More About Kombucha Side Effects

Making kombucha at home is fairly easy, especially if you buy a kit that includes everything you need. A complete kit will include all your supplies except for water. If you’d like to go more DIY, you can buy just the SCOBY and add it to your own tea mixture. (2,17)

Tools and Ingredients Needed

After buying the SCOBY online, you’ll need the following tools and ingredients.

• A clean glass jar, like a Mason jar
• A clean pot
• A mixing spoon
• 1 quart of distilled water
• ¼ cup white sugar
• ½ cup distilled white vinegar
• Green or black tea leaves or tea bags
• A coffee filter
• A rubber band

8 Steps for Making Kombucha

1. Boil the distilled water in your clean pot.
2. Add the tea and let it steep for 5 to 10 minutes.
3. Remove the tea.
4. Add the sugar and stir until it blends.
5. Let the mixture cool.
6. Add the SCOBY, then the starter tea on top.
7. Cover the jar using the coffee filter and rubber band.
8. Let ferment at room temperature for a week.

It’s important to remember that brewing at home can cause contamination, which is dangerous when you’re working with bacteria because you could accidentally grow something that makes you sick.

You’ll want to make sure all your materials are sterile to avoid introducing unwanted germs or bacteria. Use glass jars instead of ceramic containers. The acids in the tea can cause lead to be released from the ceramic glaze, which can be poisonous. (3) You can also turn to books on making kombucha at home, like the bestseller The Big Book of Kombucha: Brewing, Flavoring, and Enjoying the Health Benefits of Fermented Tea.

Learn More About How to Make Kombucha at Home

You used to only be able to find popular brands of kombucha at health food shops and specialty grocery stores like Whole Foods and Trader Joe’s. Now you can pick up a bottle at Target, Walmart, and Costco or buy them online through a brand’s website or on Amazon.

Kombucha products sold in U.S. stores are subject to regulation by the FDA, so they’re generally considered safe, per past research. (18)

When looking for kombucha, make sure to check the label. Some brands can be very high in sugar. Try to stick to no more than 5 g of sugar per serving. The most health benefits will come from a drink that isn’t high in sugar and has a lot of active cultures.

Here are some well-known and well-liked brands that are also relatively low in sugar:

• GT’s Kombucha
• Health-Ade Kombucha
• Brew Dr
• Holy Kombucha
• Ucha Kombucha

Kombucha has fallen in and out of style as a natural remedy for several years. While more research is needed to know the true effects of this tea on your health, it’s safe for most people to consume and at the very least makes for an energizing beverage that is relatively low in sugar.

Additional reporting by Melinda Carstensen.