"Fermented tea has been consumed in China for 5,000 years," Ella Davar, R.D., C.D.N., told mindbodygreen. And because kombucha starts with a tea base, the end product will likely have some caffeine in it – but there are a few factors that can affect how much.
"Unflavored kombucha generally has a small amount of caffeine per eight ounces," says Davar – but not all kombucha is unflavoured, nor is it processed in the exact same way, which can affect the final caffeine and nutritional profile. "So the manufacturing technology, microbiota, by-products, and physico-chemical properties are important facts that need to be considered," she says.
Most importantly, your carbonated drink doesn't have as much caffeine in it as the tea it was started with. During the fermentation process, some of the caffeine is carried away, so most kombucha have less caffeine than the average cup of coffee.
People who are particularly sensitive to caffeine, or who have cut out caffeine entirely, may notice the small amounts. However, if you're used to having a cup of coffee (or two) a day, the low caffeine levels in kombucha are unlikely to be noticeable.