The science doesn’t match the hype for this popular drink

Kombucha is taking the world by storm. In 2019 alone, the global kombucha market was worth $1.67 billion, according to one market analysis report. And that momentum isn’t expected to slow any time soon, with an anticipated compound annual growth rate of 19.7% through 2027. Seemingly every day, brands look to cash in on kombucha’s increased demand by launching new kombucha-based products and heavy-handed marketing blitzes, with bold claims about the fermented drink’s diverse health benefits. But, one big question remains: Are these health claims scientifically supported?

The drink’s success is based on “growing consumer preference for functional drinks over carbonated drinks and juices, along with awareness regarding the inherent nutritional benefits of the drink,” according to the market analysis report. However, there’s just one problem with that statement—the clinical evidence is mixed when it comes to kombucha’s health benefits. It isn’t clear whether the beverage actually has any positive functional or nutritional value. Let’s delve a little deeper into some of the theories surrounding kombucha’s health benefits, clinical evidence from the literature, and scientifically supported solutions for those who might want to achieve those benefits.

What is kombucha?

Kombucha is a fermented beverage made with tea, sugar, bacteria and yeast. It’s made by adding a colony of bacteria and yeast to sweetened tea and then allowing the mixture to ferment for 1-3 weeks, followed by a 2-week bottling and carbonation period. The drink has ancient origins that can be traced back to northeast China, where it first appears in the historical record about 2,200 years ago as a beverage highly prized for its purported detoxifying and energizing properties.

In the United States, kombucha’s grip on the market started with gradual adoption in the 1990s, followed by increasing growth throughout the 2000s. Then came a meteoric rise in popularity after a regulation crisis in 2010, when an audit at a Whole Foods in Maine found that the store’s kombucha bottles contained alcohol levels that ranged from slightly over 0.5% to more than 2.5%. The debacle led to a wave of publicity. By the next year, kombucha sales had increased by 28%. Since then, the drink has seen impressive growth, bolstered primarily by increased attention and the strength of its health-focused marketing.

Is kombucha really good for you?

Take a look at any kombucha bottle and you’re likely to find a host of health-focused marketing copy. One leading brand of kombucha is even called Health-Ade (not to be confused with a health aid—something that you might expect to help your health). On its website, the brand claims that its drink is “low key good for you” and that it exists to be “champion of the happiest and healthiest you.”

Despite bold claims from the brands that produce kombucha and the people who drink it, it’s doubtful that the beverage can help anyone achieve these health goals. For instance, one study found that proponents believed the beverage could help detoxify the blood, reduce cholesterol, reduce blood pressure, promote liver function, relieve bronchitis, and even improve eyesight, among other things—but there was no scientific evidence to support any of these claims.

“Kombucha is often claimed by enthusiastic supporters as a remedy for everything and a miracle elixir… The list includes the elimination of gray hair, the increase of sex drive, the improvement of eyesight, to the utilization as a household cleaner, underarm deodorant or soothing foot soak. Our review of the scientific literature revealed a lack of evidence to support many of these claims and raised doubts as to the validity of others,” wrote the authors.

What’s more, many of the stated benefits that do point to scientific evidence were tested in rats and mice. In one systematic review, for example, University of Missouri researchers could find only one study reporting the results of empirical research on kombucha in humans. “The nonhuman subjects literature claims numerous health benefits of kombucha; it is critical that these assertions are tested in human clinical trials,” the authors wrote.

A gaping research hole in humans means that kombucha’s effects on human health are unclear at best and dangerous at worst. In another systematic review, the investigator found no clinical studies related to the efficacy of kombucha as a health remedy. But, the review unearthed several case reports and case series that raised doubts about kombucha’s safety, including suspected liver damage, metabolic acidosis, and cutaneous anthrax infections. The investigator even found one fatality tied to kombucha.

“On the basis of these data it was concluded that the largely undetermined benefits do not outweigh the documented risks of kombucha. It can therefore not be recommended for therapeutic use,” concluded the review author.

The drink poses further risks to the increasing number of people who are brewing their own kombucha at home. “Kombucha tea is often brewed in homes under nonsterile conditions, making contamination likely,” wrote Brent A. Bauer, MD, in an article for the Mayo Clinic. “When improperly manufactured ceramic pots have been used for brewing, lead poisoning has occurred—the acids in the tea can leach lead from the ceramic glaze.”

Is there any hope for kombucha?

Despite a lack of scientific support for the health benefits of kombucha, absence of evidence is not evidence of absence. Based on the drink’s chemical composition, it’s reasonable to assume scientists might one day discover beneficial effects tied to its consumption. Here are a few key ingredients in kombucha that have been linked to health benefits in other products:

Probiotics. Kombucha contains species of bacteria that have been linked to probiotic function, and probiotics are a known contributor to gut health.

Caffeine. Most kombucha contains caffeine, which has been shown to boost metabolic rates, reduce the risk of type 2 diabetes, ward off dementia, and even reduce the likelihood of developing many types of cancer.

Antioxidants. These compounds are found in most types of kombucha, and extensive research has linked antioxidants to numerous health benefits, including anti-aging properties.

Acetic Acid. A byproduct of the fermentation process, acetic acid has been shown to have antimicrobial properties, which could help reduce levels of harmful bacteria.

Kombucha in a nutshell

Until scientists can take a closer look at kombucha’s effects on human health, we’ll be left wondering whether the drink is doing us more harm than good. However, thanks to animal studies and the benefits that the drink’s ingredients have displayed in other foods, there’s reason to believe that we might one day uncover data suggesting that kombucha brings some of the benefits that its proponents purport. As long as that data remains to be discovered, though, kombucha’s health benefits won’t match the hype.