Q: I’ve heard that drinking kombucha is good for the gut and for metabolic health. Is that true?
Gabriela Fraiz, a doctoral student in Brazil, said she has noticed improvements in her gut health since she started drinking a little kombucha with her lunch. She’s less bloated and gassy, she said, and she’s been more regular. She also loves the “fizzy, slightly citrusy and sweet” taste of the fermented tea, which she brews herself.
On social media, posts about kombucha’s health benefits go much further, with some claiming the drink can help you lose weight, manage Type 2 diabetes and lower the risk of heart disease and cancer.
While some limited evidence hints at certain benefits, most claims about kombucha on social media aren’t backed by human research, said Ms. Fraiz, who has studied the tea during her work on her Ph.D. in nutritional sciences at the Federal University of Vicosa in Brazil.
Here’s what we know.
What is kombucha?
Kombucha is made from tea, sugar and a symbiotic culture of bacteria and yeast (called a SCOBY).
As the mixture ferments, yeast convert the sugar into alcohol and carbon dioxide, making kombucha fizzy. Bacteria then convert most of the alcohol into acids, giving the drink a vinegary taste.
The resulting brew contains caffeine, healthful plant compounds (called polyphenols) and some alcohol, though commercial versions must have less than 0.5 percent of alcohol or be labeled an alcoholic beverage.
Kombucha is naturally low in sugar, but some manufacturers add more sugar or fruit juice to make it sweeter, said Heather Hallen-Adams, an associate professor of food science and technology at the University of Nebraska-Lincoln. It can also be flavored with whole fruits, herbs or spices.
Most kombucha contains live yeast and bacteria, though some commercial products are pasteurized or filtered to eliminate those microbes, making it more shelf stable, said Justin Sonnenburg, a professor of microbiology and immunology at Stanford.
Can kombucha benefit your health?
Some animal studies have linked kombucha to a number of health benefits, including reduced inflammation and better blood sugar control. But researchers have conducted only a handful of clinical trials in humans, and they tend to be small, with limited and sometimes lackluster results.
In a 2024 randomized controlled trial of about 60 people with excess body weight, Ms. Fraiz and her colleagues found that those who drank about seven ounces of kombucha every day for 10 weeks did not lose more weight than those who did not. The kombucha group also did not have significant changes to their gut microbes, though they did experience less acid reflux and bloating and fewer hard stools, Ms. Fraiz said.
In another limited trial from 2024, 16 participants who consumed two cups of kombucha every day for four weeks showed no improvement in their blood pressure, cholesterol or inflammation levels compared with eight participants who did not drink it.
Other human studies have suggested that kombucha may help with blood sugar control, but more research is needed. In one study from 2023, 11 healthy adults consumed a meal of rice, peas and soy sauce on three separate days with a different drink each day — soda water, a sugar-free diet lemonade soft drink, or kombucha. When the participants drank kombucha, their blood sugar responses after the meal were about 20 percent lower than they were with the other drinks.
A trial from 2023 also found that drinking one cup of kombucha every day for four weeks significantly reduced fasting blood sugar levels in people with Type 2 diabetes. Those results were promising, but the study was too small (involving only 12 people) to draw firm conclusions, said Dr. Dan Merenstein, a professor of family medicine at Georgetown who coauthored the study.
We don’t have enough high-quality research to say whether drinking kombucha alone is beneficial, Dr. Sonnenburg said. But some limited studies suggest that eating a variety of fermented foods — including kombucha, yogurt, kefir, kimchi and sauerkraut — is linked to a healthier microbiome and lower inflammation throughout the body.
What do experts recommend?
Dr. Sonnenburg is cautious about overselling the potential benefits of kombucha. That said, a low-sugar version is unlikely to be harmful and can be a more healthful alternative to drinks like sugary sodas or cocktails, he said.
If you’re buying kombucha from a store, look for one with a short ingredient list of just tea, sugar and maybe fruit juice, herbs or spices. And avoid those high in added sugars; some have 10 grams or more per serving.
If you want to try brewing your own, Dr. Hallen-Adams recommended buying a SCOBY from a reputable retailer. Homemade batches are susceptible to contamination with harmful bacteria or mold, so make sure to maintain a clean brewing environment and follow instructions carefully. If you see signs of mold, toss the batch and the SCOBY.
People with compromised immune systems may want to stick with store-bought versions, Dr. Merenstein said. Though rare, there have been a few cases of severe illness linked to kombucha, mostly from homemade brews. These have included liver injury and acidosis, or high acid levels in the body fluids.
Alice Callahan is a Times reporter covering nutrition and health. She has a Ph.D. in nutrition from the University of California, Davis.
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