Is Kombucha Good for You?

Kombucha is a fermented tea drink, usually made from black or green tea, sugar, and/or fruit juice, and a combination of live cultures called a SCOBY (symbiotic culture of bacteria and yeast). The process of making it is similar in a way to sourdough bread—you can even use a SCOBY to make sourdough starter.

“The first step to make kombucha is to steep the tea in boiled water, then add sugar or juice so there is something for the microbes to ferment,” says Chris Curtin, PhD, an associate professor of fermentation microbiology at Oregon State University. The SCOBY (usually obtained from the previous batch of brew) is then added, along with some of the liquid from another batch, and it’s left to ferment for one to three weeks before being bottled and refrigerated. The end result: a mildly vinegary, slightly sweet, bubbly beverage.

According to the trade group Kombucha Brewers International, kombucha is also sometimes referred to as “mushroom tea” because of how the SCOBY floats around in the brew, looking like a mushroom cap. Without knowing what it is, seeing one in a batch of fermenting “booch” might be enough to deter you from drinking it, but it’s essential for the drink to have health benefits.

Boosting probiotic intake is why many people drink kombucha, and these compounds are often credited for the drink’s purported benefits.

Like other fermented foods—such as yogurt, kefir, and kimchi—kombucha contains these good bacteria. “There’s general agreement that people should be eating more fermented foods because probiotics may help maintain the body’s microbiome, the collection of healthy bacteria that lives in our bodies and are important to health,” says Amy Keating, RD, a Consumer Reports nutritionist.

The benefits of probiotics might not be as clear or as vast as some of the claims suggest, however. Probiotics are thought to play a role in digestive health and immunity, but more research is needed. “While specific strains of probiotics have been shown to help very specific health-related conditions such as irritable bowel syndrome or traveler’s diarrhea, it’s not clear what benefits you would achieve from kombuchas, given the variability in how they are formulated and the limited research,” Keating says. Some of the commercial kombuchas are made with strains that have shown some benefit in studies, but those studies weren’t done with kombucha as the delivery method, Curtin says. 

Several kombucha brands list the amount of probiotics, and sometimes even the type of bacteria, on the label. Probiotics are measured in CFU, or colony forming units, which are the number of viable cells a product contains. It may look impressive to see 1 billion or more CFUs on a bottle, but there’s no standard testing to verify how many probiotics make it into the brew—and it’s not always clear how many CFUs you’d need for any potential benefits.

If the bacteria are to be helpful, they have to be alive. The CFU is usually what the count is at the time of bottling. But bacteria die over time, so you don’t know what you’ll be getting by the time you drink it. 

Curtin’s lab recently measured how many live bacteria there were in different store-bought kombuchas. “We found that the probiotic counts were all lower than those reported on the bottle,” he says. “However, we don’t know how long it had been since the products were bottled.” He suggests drinking kombucha shortly after purchase and keeping it refrigerated to maximize probiotic shelf life.

Another thing to note is that while authentic kombucha is raw and not pasteurized, some brands do pasteurize to ensure that there is little risk for harmful bacterial growth and/or to extend shelf life. Pasteurization, however, destroys the live probiotics. Some producers, especially those that list specific strains on the labels, may add probiotics after pasteurization, Curtin says.

Another boon for kombucha is that it contains the same beneficial compounds as the tea it’s made from. These include catechins, polyphenols, and flavonols, which act as powerful antioxidants to help prevent cell damage in the body. While commercial kombuchas can contain good amounts of antioxidants, one study from researchers at Asbury University in Kentucky found that homemade brews had an average of twice the total antioxidants of store-bought kombuchas. 

Additionally, the fermentation of kombucha produces biologically active acids, including acetic and glucuronic acids, which may contribute to kombucha’s purported benefits. Studies have shown that these acids may also have some antibacterial activity, meaning they prevent harmful bacteria from developing in the drink itself.

Kombucha can’t be made without some form of sugar for the yeast and bacteria to feed on during fermentation. However, the longer the fermentation period, the more sugar the bacteria consume, and the less that’s in the final drink.

Unsweetened kombucha can taste sour, so most producers do add juice, more sugar, or no-calorie sweeteners.

In general, kombucha is lower in calories and added sugars than sweetened iced teas, lemonades, and sodas. For example, GT Synergy Kombuchas have natural sugars from the 5 percent fruit juice they contain, but no added sugars.

Some, though, can still contain a fair amount. For example, a 16-ounce bottle of Health-Ade Ginger Lemon has 14 grams of added sugars—a little more than half the 25 grams the American Heart Association says is the maximum women should have in a day. (Men should have no more than 36 grams.) 

Other kombuchas have no or low added sugars, but they do contain alternative sweeteners, such as monk fruit. So if you prefer to avoid these, check the ingredients lists as well as the added sugar content on labels. 

Due to the fermentation process, all kombucha can contain alcohol, but it can’t be sold as a soft drink if it exceeds 0.5 percent alcohol by volume (ABV).

Hard kombuchas, a growing category, undergo additional fermentation cycles to intentionally increase the alcohol content. Most have less than beer (which averages about 5 percent ABV), ranging from 3 percent to 8 percent ABV. The ABV will be clearly marked on the can or bottle.

Brewing your own kombucha can be safe, but if you don’t carefully follow sanitary practices, mold or bad bacteria that can make you sick can grow in your drink. Be sure your hands and work surfaces are clean, and sterilize containers. Also use food-grade containers to make kombucha. For instance, it’s best to brew in glass or stainless steel vs. ceramic or clay containers, which may lead to lead poisoning under certain conditions.

Mild unpleasant, but not dangerous, side effects from drinking kombucha have been reported, including upset stomach, bloating, and gas. Start slow. According to the Michigan State University Extension, “the recommended dose of kombucha is one-half cup per day, but most commercial kombucha is sold in much larger quantities, and it is not common public knowledge that this beverage is intended to be consumed in small amounts.”

Additionally, because of its acidic nature, drinking too much kombucha on a regular basis can deteriorate tooth enamel, which can lead to more cavities and teeth sensitivity. Dentists recommend drinking water after kombucha to rinse away the acidity. Just don’t brush your teeth right away, because they’re more prone to enamel damage right after drinking something acidic.

Some people may also need to avoid kombucha or control how much they drink due to the sugar content. And because kombucha contains live organisms and some brands are unpasteurized, people with compromised immune systems and those who are pregnant should check with their doctor before consuming it; parents should check with their children’s doctor before giving it to their kids.