Issues in Kombucha Pt. 1: Science v. Nature

In the first of an ongoing series examining issues related to the kombucha industry, we examine how the clash between hard science and unverified evidence regarding the fermentation process and health benefits of kombucha is shaping the category both consumers and producers.

After a long climb towards the mainstream, kombucha has undoubtedly arrived.

Far from the days when it was viewed as a curious brew made at home by long-haired hippies, in 2017 the category has become a fixture of the beverage segment across all retail channels. A proliferation of regional independent brands, are positioned now from as much of a mainstream perspective as an artisanal one. Growing awareness and curiosity, meanwhile, has spurred innovation and acceptance in the marketplace while attracting the interest of investors and larger companies seeking to quench consumers’ increasing thirst for better-for-you beverage products. According to market research firm Technavio, the global kombucha market was valued at $700 million in 2015 and is expected to grow at a compound annual growth rate (CAGR) of close to 15 percent from 2017 to 2021.

Yet for a beverage with such rapidly expanding popularity, kombucha remains a category with ample room for exploration from a scientific perspective. For the industry to truly thrive, science and salesmanship need be running in step with each other, and efforts are underway to help close the gap.

Expanding research in kombucha has the potential to impact the industry in several key areas. After being broadly associated with various health benefits for decades, studies into the effects of kombucha on humans would provide a scientific basis for those claims to be either confirmed or rejected. Science can also help establish the foundation for which the industry can begin to shape accepted norms and best practices, particularly in safely guiding inexperienced kombucha brewers through the unique fermentation process. The spectre of suffering another devastating recall related to food safety violations, similar to events in 2010, looms in the background, adding extra motivation for companies to embrace deeper inquiry into the science of kombucha. Yet considering the resources required to launch such investigations, a more complete understanding of kombucha is still being formed, and is far from guaranteed.


For as long as people have been consuming it, drinking kombucha has been associated with various health benefits, such as boosting liver function, aiding digestion and supporting a strong immune system. Anecdotal evidence has been influential in promoting acceptance of kombucha as a wellness tonic. Brands with names like Health-Ade and Revive help consumers associate their product with a healthy lifestyle, while GT’s, a category leader, proudly displays a note the founder’s mother, Laraine Dave, on its website in which she credits kombucha for helping her treat a rare, aggressive form of breast cancer.

Yet the truth is that clinical studies examining the efficacy or effects of kombucha on humans are virtually nonexistent, leaving the category wide open to subjective interpretation. While scientists agree that kombucha has high levels of B vitamins and demonstrates evidence of antimicrobial activity, several of the more specific claims — such as antioxidant effects that can help treat cancer, or stimulation of the immune system — have only been shown in studies using animals, according to the Memorial Sloan Kettering Cancer Center.

Kombucha brewers have taken different approaches based on their respective retail strategies and routes to market, making some broader generalizations inaccurate. Probiotic content, for example, can differ significantly from one brand to another, while some focus exclusively on prebiotics. The category is also stratified in terms of shelf-stable and refrigerated products, as well as glass versus plastic bottles.

As director of the fermentation sciences department at Appalachian State University in Boone, N.C., Dr. Seth Cohen has a broad background in various types of naturally fermented foods and beverages, from wine to kimchi and sauerkraut. He said that the “renaissance” around such products as a whole, which consumers view as both flavorful and healthy, was helping spur research in kombucha.

“Because of this interest, you definitely see more and more research where people are trying to first understand what’s actually in these products,” he said. “There’s certainly been a lot more literature that I see pop up relating to fermented products and what they can do potentially, what are the health benefits.”

Without verified evidence, kombucha brands are limited in the claims they can make on packaging or marketing materials, leaving room for other factors to influence consumers’ decision to purchase.

“It’s not deceptive, it’s not dangerous, but there’s no scientific literature behind it,” Cohen said of kombucha’s use as a disease treatment or health remedy. “You can’t say drinking kombucha reduces your risk of heart failure. Those studies certainly aren’t there. But people have been tracking down those things in the last ten years at a much more rapid clip than before.”


While most studies have focused on evaluating methods of measuring or controlling sugar and alcohol levels in kombucha, there is some indication that the unique characteristics of each individual kombucha culture may play an outsized role in influencing its biochemical composition. Dr. Cohen conducted an experiment in which he fermented a sweet tea using four different commercial kombucha cultures, producing four batches under different temperatures.

“Our concept was — if we take a culture and we have it in cold or warm conditions, do those conditions of the fermentation drastically impact the accumulation of alcohol?” Cohen said. He also had two levels where oxygen was introduced to the room twice a day during fermentation to see if it would potentially discourage yeast metabolism for ethanol production.

“The three cultures that showed us issues with high alcohol, it really didn’t matter too much what we did to it,” Cohen said, calling the results a surprise. “We kind of assumed that you take a culture and depending on the conditions and the temperature and even aeration, the things we know we can control easily, we should see some difference. And we really didn’t.”

While advocating for the experiment to be replicated several more times before drawing any more specific conclusions, Cohen noted that the results were “definitely something I was surprised by.”

“One of the things I learned,” he added, “was that if you have a good culture that tends to produce what you desire, that’s kind of your biggest strong point right there.”

The fact that each culture is a unique living organism that responds differently to environmental conditions and stimuli means that getting consistent results can be a challenge. According to Cohen, there is no exact ratio of yeast to bacteria that will ensure alcohol will stay within the range of compliance beyond the typical four-week shelf life.

“I haven’t found anyone who’s shared with me yet that they’ve sorted anything out besides pasteurization or ultra filtration, which ultimately, for many, defeats the purpose,” Cohen said.


At this year’s KombuchaKon, the annual conference organized by trade group Kombucha Brewers International, over 130 member companies met at the Long Beach Convention Center in Southern California to discuss the present and future state of the industry.

During their presentation at the event, Matt Thomas, co-founder of Brew Dr. Kombucha, and Jeff Weaber, founder of Aqua ViTea, shared their experiences in building a kombucha company based on a solid understanding of the tea’s unique fermentation process.

When the pair first began collaborating in 2009, Weaber used funding from a grant to study the biological composition and behavior of kombucha, while Thomas researched a mechanical solution to regulating alcohol. Following in the model of beer and wine producers, Weaber assembled an in-house microbiology lab to study the various organisms in kombucha in hopes of understanding how to get them to behave in a consistent and predictable fashion. The ability to project how the living organisms present within the beverage will act and respond under different conditions is critical in helping brewers avoid the likelihood of another recall.

The problem, according to Thomas, is that, compared to beer and wine, collective understanding of kombucha remains in a nascent stage, mainly because of the considerable resources required to produce studies and fund research. Until such time as those resources become available and further research is completed, which he predicts will take no less than a decade, Weaber conceded that there are no easy answers for smaller brands and upstarts seeking to reproduce their home brews safely and consistently on a large scale.

“People coming into [the industry] need to be educated so they’re not naive to what’s going on,” said Weaber, noting that KBI has been “great about pulling all these people together.” “But I don’t know if [KBI] has been as transparent as they should be about the situation that we are in and letting small producers know that this is a challenge and if you don’t have it figured out, you should really put yourself in the 21-plus category until you figure it out.”

Moreover, Weaber said that the lack of consensus across the industry as to best practices for kombucha formulation and fermentation could also be influencing companies to be hesitant about revealing their own processes.

“Part of our message is that people need to collaborate,” Weaber said. “I talked to a large producer of shelf-stable kombucha recently. Apparently they have some biology figured out that can verifiably recreate a consistent kombucha product, but they aren’t willing to talk about it. They are keeping it proprietary. That’s not really helping the whole industry.”

Thomas agreed. “You go to a craft beer conference and everybody is talking and sharing information. I think it just shows the infancy of the category and people are just getting started and are scared and are trying to protect what they have.”

For their part, Thomas and Weaber are hoping to lead by example by being as transparent as possible. At KombuchaKon, Thomas shared details of Brew Dr.’s production process, including the use of a large machine called a spinning cone column. By reducing atmospheric pressure in order to atomize ethanol at a low temperature, the machine can separate and extract ethanol from the liquid without heating it over 100 degrees, resulting in product that retains its naturally occurring probiotics and has a ACV of .2 percent.

“If you don’t have [alcohol control] figured out, you should really put yourself in the 21-plus category until you figure it out, or the people that have figured it out need to share it,” said Weaber. “That’s why Matt and I share what we’ve discovered mechanically, but also what we’ve learned biologically along the way. We encountered some other companies there that are supposedly making kombucha in a biologically controlled method, and they need to share that with these young producers. Otherwise, they are scaling up their businesses in a very scary situation, kind of building it on a house of cards.”

And yet in-depth analysis of ethanol production and SCOBY composition in kombucha may obscure a more salient point: sales figures plainly show more and more consumers like the stuff, regardless of verified health claims or not. As it continues to become more ubiquitous in the mainstream alongside other fermented products, more attention and scrutiny from the scientific community will be a likely consequence.

“I think with kombucha, you are seeing a lot of push from the medical community towards acknowledging the importance of gut health and there’s more and more studies going on around how fermented foods help provide the gut with something it must be missing,” said Thomas. “I’m encouraged that the medical community is also kind of doing studies that can incorporate kombucha, because there’s obviously a lot more resources than the kombucha industry is going to have.”