Your gut health isn't just dictated by what you eat — it's also affected by what you drink. When it comes to nourishing your microbiome, tea ranks high on the list. And what's at the top for many gastroenterologists? Kombucha.
Kombucha is a fizzy fermented tea — usually made with black tea — that's rich in probiotics. In fact, gut health-promoting probiotics are a byproduct of the fermentation process. Probiotics are "good" strains of bacteria that promote healthy microbes in your gut, according to the Mayo Clinic.
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"Most of the benefits of kombucha are its probiotics. It helps [provide] a good population of bacteria and decrease or eliminate bad populations," says Andrew Boxer, MD, a gastroenterologist at the Gastroenterology Associates of New Jersey.
Although taking probiotic supplements has increasingly become more popular, these pills aren't regulated by the Food and Drug Administration (FDA). That means supplement companies can make claims about their products' benefits without FDA approval to back them, per the National Center for Complementary and Integrative Health.
Eating and drinking your probiotics through a variety of fermented foods, like yogurt, kefir, kimchi, sauerkraut and kombucha, can help ensure you're getting all types of good strains of bacteria.
Here, we outline all the reasons kombucha supports your digestive health.
Why Kombucha Is Good for Gut Health
1. It's an Excellent Source of Probiotics
Having a proliferation of good microbes in your gut is important for keeping disease-promoting bacteria in check.
When there are too many bad bacteria present in your gut due to stress, illness and unhealthy habits, it can lead to dysbiosis — a lack of microbial diversity — which are linked to chronic diseases, such as inflammatory bowel disease (IBD), obesity and cancer, according to an April 2015 review in the International Journal of Molecular Sciences.
"You're getting probiotics in kombucha because of the fermentation process," says Aditi Chhada, MD, a gastroenterologist at the Gastroenterology Associates of New Jersey. "Plus, you're getting antioxidants and vitamins [from the tea] that are produced during the fermentation process. These polyphenols in tea become more available for our body to utilize."
The fermentation process produces bacteria that promote diversity of the microbiome and more antioxidants than what's originally in the tea, according to Dr. Chhada.
"There was a 2021 study by the Stanford research group that basically looked at fermented foods, kombucha included, and gave people [foods] rich in fermented foods as well as foods rich in fiber. What they found was that a fermented food diet, which included kombucha, caused a significant decrease in inflammatory markers in those people," Dr. Chhada explains.
According to this small July 2021 study in Cell, which included 36 adults who followed a 10-week diet, large servings of fermented foods and drinks like kombucha increased overall microbial diversity.
That same study found that eating more fermented food resulted in a decrease in cytokine levels. Elevated cytokine levels at a steady state are linked to chronic, low-grade inflammation.
2. It Contains Polyphenols
Probiotics aren't the only reason that kombucha is a good drink choice for promoting a healthier and more balanced microbiome. Because tea is the base of kombucha, it also contains these powerful chemicals called polyphenols that help reduce inflammation in your body, Dr. Chhada says.
"Tea, in general, whether you're talking about green tea, black tea, oolong tea or white tea, contains polyphenols, which are chemicals in plants that have certain antioxidant properties. And in general, antioxidants are chemicals that protect the cells of the body from components that are responsible for damage in the body, such as free radicals," she says.
Dr. Chhada notes that green tea naturally has more polyphenols than black tea because of how it's processed. Many store-bought kombuchas have a combination of black and green teas, including brands like Health-Ade and GT's Synergy.
In terms of what to look for when shopping for kombucha, Dr. Chhada recommends those that have less than 0.5 alcohol by volume (ABV) and those that are low in sugar. Generally, you want to avoid kombucha and other drinks with a very high ABV because alcohol has cancer-contributing properties, she says.
3. It May Support Your Immune System
The bacteria in your gut interact with your immune system. It's not completely clear how the composition of your gut affects your immune system, but studies show that cancer may be the result of changes in the makeup of your gut, according to Johns Hopkins Medicine.
Although there aren't any well-designed studies specifically on the effects of kombucha on the gut health of people living with IBD or IBS, small studies have shown that the polyphenols in tea can help reduce colon cancer cells, Dr. Chhada says.
According to a September-October 2013 review in Biotechnology Advances, foods containing polyphenols, such as vegetables, tea, coffee and chocolate, are linked to a lower risk of cancer development. Some of these polyphenols have been shown to be protective against colon cancer because of their chemoprotective properties.
The thing is, you have to drink large amounts of tea — about 4 to 5 cups a day — to get these effects, which isn't practical for most people, Dr. Chhada says.
In terms of how much kombucha you should drink, Dr. Chhada recommends a cup a day. "But the data is still out as to what would actually provide enough to make a health impact."
Bottom line is that when combined with fermented foods, kombucha can greatly benefit your microbiome, and in turn, your overall health.
- Mayo Clinic: "Prebiotics, Probiotics and Your Health"
- International Journal of Molecular Sciences: "Impacts of Gut Bacteria on Human Health and Diseases"
- National Center for Complementary and Integrative Health: "Probiotics: What You Need To Know"
- Cell: "Gut-Microbiota-Targeted Diets Modulate Human Immune Status"
- Biotechnology Advances: "Nanoencapsulation of Polyphenols for Protective Effect Against Colon–Rectal Cancer"
- Johns Hopkins Medicine: "The Gut: Where Bacteria and Immune System Meet"