If you haven’t noticed the recent craze for kombucha, you must be living under a rock. The fizzy health drink claims to promote gut health because of the live bacteria, also known as probiotics, it contains.

However, we have some bad news for kombucha fanatics and other probiotic health nuts.

What Are Probiotics?

Probiotics are live bacteria and yeasts found in different types of food such as yogurt, kimchi, sauerkraut, kombucha, sourdough bread, and more. Previously, these items were thought to boost gut health by promoting the “good” kind of bacteria over the bad. However, two new studies say otherwise.

Researchers found that most people’s digestive tracts actually prevent the probiotics from doing anything. Furthermore, probiotics could even delay the return of healthy gut bacteria after one uses antibiotics.

Getting Gutsy

In the first study, researchers sampled 25 people’s guts via endoscopies and colonoscopies. One group took the probiotics while the other group was given a placebo. The researchers found that the probiotics were only able to colonize some of the probiotic group’s guts, but not all. Although, the probiotics ended up in each person’s stool who used them.

This goes to show that when you’re drinking kombucha or indulging in a yogurt, all that good stuff likely just goes in one end and out the other.

Delayed Microbiome Bounce Back

In the second study, 21 individuals were given antibiotics to test whether probiotics could repopulate gut bacteria. They were then split into three groups. The first group let the gut recover on its own. The second group used probiotics. The third group was given a transplant of their own bacteria through a fecal microbiome transplant.

Through the study, researchers discovered the probiotic group took months longer to return to normal than the other groups.

“Contrary to the current dogma that probiotics are harmless and benefit everyone, these results reveal a new potential adverse side effect of probiotic use with antibiotics that might even bring long-term consequences,” the study’s senior author Eran Elinav said.

Admittedly, the researchers acknowledged probiotics aren’t totally useless, and more research needs to be conducted to determine their effects (or lack thereof).

In the meantime, I’m rethinking my recent $4 kombucha purchase.