If celebrities like Gwyneth Paltrow and Madonna are to be believed, kombucha can relieve almost any symptom that might ail you, from poor digestion to active acne. And it's not just Gwyneth and Madonna, mind you. Kombucha has been heralded as a cure-all health drink for decades. But what are the health benefits of kombucha, really? And is there any science behind the claim that drinking kombucha is good for your health?

To better understand why so many people believe in the health benefits of kombucha, it's good to first understand what's in a bottle of the stuff. "This traditional Asian beverage is a type of fermented tea that's slightly effervescent and enjoyed cold," writes Maria Marlowe, CHC, in The Real Food Grocery Guide. The drink starts with a symbiotic culture of bacteria and yeast, or SCOBY, which is added to tea. The SCOBY and the tea sit together in a bottle or a jar until they ferment; that's what creates the bubbles and the drink's signature tartness. "High-quality brands are unsweetened," Marlowe explains, "or use just a touch of fruit or vegetable juice for flavor." That's how you end up with lemon or ginger kombucha.

The supposed health benefits of kombucha stem from the bacteria, also known as probiotics, that make up the SCOBY. Probiotics are found in a bunch of different, mainly fermented foods, including yogurt, and they are known to help with digestive issues. As Sean Lovett, cofounder of Revive Kombucha, explained to me in an email, "If it’s naturally fermented, it will have live probiotics that aid digestion and assist metabolism. It’s got a host of organic acids and vitamins that are good for you!" Trevor Ross, CEO and founder of Live Soda, agreed, once telling me, "This is my personal opinion, not a company statement, but I believe that probiotics play an important role in supporting healthy digestion and 'gut health,' with the good bacteria contributing to a healthy microbiome."

The scientific evidence backing up these claims with regard to kombucha are less concrete, however. A 2003 review of literature published in a German scientific journal stated that, "No clinical studies were found relating to the efficacy of this remedy," adding that the drink couldn't be recommended for therapeutic use because, "the largely undetermined benefits do not outweigh the documented risks of kombucha." A more recent review of literature, published in 2014 in the Journal of Medicinal Food came to a similar conclusion. Though the researchers found plenty of anecdotal evidence of the benefits of kombucha, which they call KT, they add, "very little scientific evidence is available that validates the beneficial effects of KT."

That doesn't mean kombucha is necessarily bad for you, though. If you're looking to limit your intake of sugar and decrease the amount of soda you drink in a day, switching to kombucha is a great choice. "Look for kombucha in glass bottles, without any added sugar—a little bit of fruit juice is OK, though," writes Marlowe. Lovett agrees, writing, "It’s a low sugar carbonated beverage that’s a great alternative to soda or energy drinks."

So will kombucha fix your GI discomfort or help clear your skin? Probably not, even if there is anecdotal evidence that says otherwise. (It should be noted here that whenever you've got a persistent health problem, you really should seek professional medical attention.) But if you're looking for a healthier alternative to soda or a way to cut down on your sugar intake without giving up your favorite fizzy drinks, kombucha isn't a bad bet.