Unless you’ve been on a social media detox for the past few years, chances are, you’ve heard of the bacteria-laden brew called kombucha—the latest health trend that sounds like anything but.

While it seems ripped from a science fiction book, kombucha is, in fact, pretty ancient: The stuff originated thousands of years ago in northeast China, where it earned rave reviews for its “detoxifying and energizing properties” in 220 B.C., according to a 2014 research review. And it’s been traveling the world ever since—to Japan, then Russia, and then Europe. Today, kombucha is big business. According to Energias, a market research firm, the global kombucha market could reach $2.8 billion by 2024.

Part of the drink’s appeal is its reputation as a cure-all: Fans of kombucha say it does everything from lower inflammation to prevent diseases like cancer. But does it really?

“It’s not proven that kombucha is beneficial for your health,” says Dawn Jackson Blatner, RDN, a registered dietitian and author of The Superfood Swap. “We know that it has good bacteria in it, but we don’t know much and what kinds.”

So does that mean you shouldn’t drink it? Not necessarily. “It’s fun, but it’s not the magical elixir that people think it is,” says Jackson Blatner. And in fact, it could make you seriously sick.

Here’s what science has to say so far.

What is kombucha, anyway?

Kombucha is a type of tea; it’s usually made with black tea, but green is also used, too. Once the tea leaves (or bags) are added to a pot of boiling water and left to steep, the tealeaves are removed and some sugar is added. Once the tea is cooled, you add a “starter tea” (like a previously fermented kombucha) and a SCOBY, an acronym for a symbiotic culture of bacteria and yeast. Then, the brew is left to ferment and breed bacteria under a full moon. (Okay, kidding about the moon.)

So, why is kombucha supposedly so healthy for you?

The concoction of microorganisms in kombucha—bacteria, yeasts, and antioxidants—have led some to speculate that it could boost your immunity, ward off cancer, and alleviate inflammation. Problem is, much of the research on kombucha has been conducted on animals, not humans, so no one knows for sure, according to the 2014 research published in the Comprehensive Reviews in Food Science and Food Safety.