How Effective Are Probiotics? They Might Not Work As Well For Everyone, A New Study Says

gballgiggs/Fotolia

You hear all the time you’re supposed to eat yogurt or take probiotic supplements to boost your digestive health, but how effective are probiotics really? Well, according to Forbes, new research featured in two papers published in the journal Cell by researchers at the Weizmann Institute of Science in Tel Aviv suggests that not only can taking probiotics not be as effective as you'd think, but might actually mess with your gut health.

According to ABC News, probiotics are live microorganisms that are found in foods like yogurt or pickled veggies, and in dietary supplements. Previous research suggests that probiotics mimic and strengthen the effects of the good bacteria that line the digestive tract and help the body absorb food and fight off infections, ABC New reports. In the U.S., probiotic supplements are a multi-million-dollar industry, says ABC News, with around 4 million adults taking some form of probiotics and up to 60 percent of health care providers prescribing probiotics to their patients. But this new research may change that.

"People have thrown a lot of support to probiotics, even though the literature underlying our understanding of them is very controversial," Eran Elinav, senior author and an immunologist at the Weizmann Institute of Science in Israel, said in a press release. "We wanted to determine whether probiotics such as the ones you buy in the supermarket do colonize the gastrointestinal tract like they're supposed to, and then whether these probiotics are having any impact on the human host."

The researchers found that many people may be resistant to the effects of probiotics, Forbes reports. The researchers had 19 people take 11 of the most commonly found strains of probiotics, says Forbes, and only eight of them had any notable bacterial colonization in their digestive tracts. That means for many of the volunteers, taking probiotics didn’t help them grow the good bacteria they needed to help their digestion and immune systems. The researchers were also able to predict which participants would successfully have any bacterial growth and which ones would just excrete the probiotics by looking at their normal microbiome and gene expression in their digestive tracts, Forbes reports.

"The benefits of the standard probiotics we all take can't be as universal as we once thought,” Eran Segal, a computational biologist at the Weizmann Institute and author of the first study, told Forbes. “These results highlight the role of the gut microbiome in driving very specific clinical differences between people.”

The researchers also found that taking probiotics after taking a round of antibiotics — thought to restore a healthy gut biome — can actually do more harm than good, The Independent reports. Antibiotics destroy the gut of all of its natural bacteria, both good and bad, says the Independent, which is why many people take probiotics after antibiotics. But the researchers found that probiotics didn’t always help the gut return to normal, says Forbes; in fact, in some participants, it significantly delayed the return of their own gut bacteria for months.

Adam Berry/Getty Images Entertainment/Getty Images

“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,” Elinav told The Independent.

According to Forbes, the researchers say the takeaway from this study is that we need to move away from a one-size-fits-all approach to probiotics. Just because they work for some people doesn’t mean they work for everyone. In fact, for some, they could do more harm than good. A more personalized approach to probiotics and microbiome-directed therapy will ensure everyone gets the individual care they need. Until then, approach probiotics with caution and talk to your doctor if you’re not sure if probiotics are right for your medical needs.