I first tried kombucha twelve years ago, at the pricey grocery store in my college town. I remember seeing the 16-ounce bottle with its $3.99 price tag, marketed with words “renew” and “rebalance.” I bought it, thinking that it must be good for me. Its slight vinegary taste and weak effervescence seemed like proof that it must have legitimate health benefits—why else would people pay so much for it?
Turns out, I wasn’t alone in thinking kombucha was some kind of magical elixir—and then buying it: The worldwide kombucha market has since grown to $1.67 billion and is expected to hit $2.4 billion by 2027, according to a 2020 market analysis report by Grand View Research.
But in reality, there's really nothing all that magical about the fermented drink. Not that kombucha is bad for you or that you're foolish for buying it (I buy it occasionally still too—the taste has really grown on me), but it's not worth drinking for its health benefits, because, frankly, there's no real evidence that any actually exist.
Here's everything you need to know about kombucha and why you may not want to tout it as a health beverage.
Kombucha is marketed as being beneficial for gut health because it contains probiotics
Kombucha is a fermented tea, made by combining brewed tea with a SCOBY—a symbiotic culture of bacteria and yeast, sometimes called a “mother”— and some sugar. Over the course of a week or two, the sugar feeds the bacteria and yeast and the drink ferments into tangy, slightly fizzy kombucha.
Although the SCOBY, which is solid and kind of gelatinous, is removed from the kombucha before drinking or packaging, many strains of bacteria remain in the drink. “It is known that many bacterial species that grow in the kombucha may have a probiotic function,” Rebecca Jaspan, MPH, RD, CDCES, a New York-based dietitian tells Health.
A quick refresher: The bacteria and other microbes living in your body make up what's called your microbiome, a relatively new area of study in health and nutrition science. Mostly, researchers are focused on the gut microbiome and how it affects health. “Probiotics are live bacteria that inhabit your GI tract,” which houses your gut microbiome, Jaspan says. “They are known as 'good' or 'helpful' bacteria” Probiotics are found naturally in fermented foods like kimchi, yogurt, and kombucha, and also sold as supplements. A diverse microbiome, with lots of probiotic bacteria, is thought to improve digestion, enhance immune function, support skin health, and lower your risk of certain diseases.
However, the jury's still out on how and whether probiotics actually work.
Some benefits of probiotics are well documented and generally agreed upon by experts. For example, a 2006 review of 25 previously conducted randomized controlled trials in the American Journal of Gastroenterology found that probiotic supplementation helped treat antibiotic-associated diarrhea, likely by replacing probiotic bacteria in your gut that antibiotics kill off.
Other than that, though, the evidence is shaky. A 2019 review in the European Journal of Clinical Nutrition looked at 45 previously conducted studies on the impact of probiotics on various aspects of health. The authors found that probiotic supplements do seem to increase the amount of healthy bacteria in the gut, although it’s unclear whether this amount of healthy bacteria remains after a person stops taking the supplements. They also found evidence that taking probiotics might help fight the common cold, but didn’t find solid evidence that probiotics help protect against or fight the flu, lower the incidence of heart disease and its risk factors (high cholesterol and high blood pressure), or help with diabetes prevention and management. Probiotics may also fight against vaginal infections by increasing levels of “good” bacteria in the vaginal area. And, there’s evidence that probiotics might help relieve GI discomfort (diarrhea, constipation, bloating), but it’s unclear how.
That's a lot of information, but the takeaway is that while probiotics have potential, there's still a lot to learn about how they work and how they might affect our health.
We really don't know anything about the specific health effects of kombucha, either.
The studies referenced above talk about the health impacts of probiotics in general, but “there is no scientific evidence for the probiotic benefits of kombucha,” Jaspan says.
One reason for this is that there’s no telling how many live probiotics are in a single bottle of kombucha. One popular kombucha brand, for example, states on its label that “at time of bottling,” a 16-ounce serving contains 6 billion probiotic organisms from three strains. The caveat? Per the FDA, while claims like this must accurately reflect the total number of these organisms in a drink —which FYI are typically added after the fermentation process, so that manufacturers can measure them—there’s really no way to know how many are alive and how many are dead. Plus, even probiotics that are alive at the time of bottling might be dead by the time you drink the kombucha. Consumers don’t really know (without lab-testing every drink before consuming it) how many probiotics are in any given bottle.
We have a bit more information about the levels of antioxidants in kombucha. A 2020 study in Antioxidants looked at the chemical profiles of various types of kombucha fermented for different amounts of time. Researchers found that while levels of polyphenols and flavonoids (two types of antioxidants) varied significantly depending on what kind of tea the kombucha was made from and how long the kombucha fermented, all types did have significant levels of these antioxidants. That’s likely good news, but we can’t say for sure what it means.
Why? Because there’s been virtually no research done on how kombucha consumption affects humans. A 2019 systematic review in Annals of Epidemiology looked into this topic, searching for previous studies on kombucha. Researchers found several studies conducted on various animals, but only one conducted in humans—a very small study of 24 adults with type 2 diabetes that lasted only three months. In other words, the potential benefits of kombucha specifically in humans—not just the benefits probiotics or antioxidants in general—are virtually unknown.
Kombucha is considered safe for most people, but even that's up for debate.
Notably, how much kombucha someone can safely drink is also a gray area. In 1995, the Centers for Disease Control and Prevention (CDC) recommended drinking no more than four ounces per day, based on the fact that two healthy women who regularly drank homemade kombucha fell unexplainably ill (one eventually died). But, kombucha was never proven to be the cause of these deaths. Cases like this are incredibly rare despite the fact that most people drink more than four ounces of kombucha at a time, so unless you’re consuming an ungodly amount of the stuff, you probably don’t need to worry about toxicity.
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Of course, you should keep in mind that kombucha might contain more alcohol than you think. Although small amounts of alcohol are created as part of the fermentation process, kombucha isn’t classified as alcohol because it typically has less than 0.5 percent ABV, the cutoff point. That said, lots of random sampling studies over the years, including this one conducted by the British Columbia Centre for Disease Control in 2020, have found that many bottle contain between one and three percent alcohol.
Because of the alcohol and the live bacteria, it's recommended that pregnant women and immunocompromised individuals stay away from kombucha. And, not for nothing, the carbonation and other ingredients in kombucha can also lead to stomach discomfort.
The bottom line: Kombucha might be tasty, but it's far from a superfood.
The idea that kombucha is a superfood is a result of marketing and wellness hype. It doesn't contain significant levels of important nutrients, and any probiotic or antioxidant benefit it might have is up for debate. Plus, “no food or drink can truly be called a superfood,” Jaspar says.
If you're drinking kombucha because you think it'll boost your microbiome or improve digestive health, Jaspar recommends changing your approach. “Eat a variety of foods. Especially fruits and vegetables, whole grains, and legumes,” which contain fermentable fiber that feeds probiotics. Once again, it boils down to the fact that a nutritious overall diet, not a single food or beverage, will give you the most bang for your buck when it comes to health.
As for the kombucha lovers out there, if you like the flavor, there's no reason you shouldn't buy the stuff—just don't expect it to magically transform your health.