Sugar-sweetened drinks like soda and lemonade are known to spike blood sugar—but what about kombucha? Despite its health halo, this fizzy fermented tea always contains added sugars, which are needed to feed the yeast and bacteria during fermentation.

With insights from experts and the latest research, we’re spilling the (fermented) tea on how kombucha really affects blood sugar levels.

Kombucha usually contains between 3 and 15 grams of sugar—at the higher end, that’s on par with some sports drinks.

Sugary drinks typically cause a rapid increase in blood sugar because they contain concentrated sugars that are quickly absorbed into the bloodstream. Unlike food, they lack protein, fiber, or fat, which helps slow down digestion.

But here’s the thing: Some of the sugar listed on a kombucha label has already been broken down during fermentation by the microbes—so the end product typically contains much less sugar than the original mix, Erin Palinski-Wade, RD, CDCES, author of 2 Day Diabetes Diet, told Health.

This could help explain why some research suggests that kombucha may not affect blood sugar as much as other drinks with similar sugar content. One small 2023 study even found that people who drank kombucha (with 1.7 grams of sugar) alongside a high-carb meal experienced significantly lower blood sugar compared to those who drank beverages with no sugar at all. 

This effect may be due to fermentation byproducts like organic acids, ethanol, and other metabolites, which “can slow the rate at which glucose enters the bloodstream by delaying stomach emptying and reducing the digestion of carbohydrates,” registered dietitian and food scientist Jennifer Pallian, BSc, RD, told Health. 

Kombucha’s antioxidants might also “help your body absorb the remaining sugars more slowly and even support better insulin sensitivity—helping to steady blood sugar levels instead of spiking them,” added Palinski-Wade.

That said, the overall research on kombucha and blood sugar has been “inconsistent,” according to a 2025 review. And some studies finding positive results, such as the one mentioned above, have had significant limitations, including small sample sizes and potential conflicts of interest due to industry funding.

Despite kombucha’s potentially less detrimental effect on blood sugar compared to other sweet drinks, Palinski-Wade said its sugar content is still something to keep in mind.

“If you’re sipping on it all day, those grams [of sugar] can still add up,” she noted. “Too much sugar, no matter where it comes from, is something we all want to keep in check.”

The Dietary Guidelines for Americans recommend that adults limit added sugars to no more than 10% of their total daily calories—or 50 grams a day for a person who consumes 2,000 calories daily. Eating too much added sugar is linked with conditions like type 2 diabetes and heart disease.

While some kombucha brands are higher in sugar, it generally contains less than soda—so if you’re a regular soda drinker, switching to kombucha could be a healthier choice.

And thanks to its beneficial bacteria and antioxidants, kombucha may even offer unique blood sugar benefits compared to other sweetened drinks.

Palinski-Wade recommends limiting kombucha intake to around 8 ounces per day. If you have health concerns like insulin resistance, prediabetes, or type 2 diabetes, experts recommend talking to your doctor about how it can fit into your diet.

People who are pregnant, immunocompromised, or need to avoid unpasteurized foods should skip kombucha altogether, Palinski-Wade said. “It can also contain small amounts of alcohol and caffeine,” she added, “so if you’re sensitive to either—or taking medications that interact with them—you’ll want to be cautious.”