Probiotics Not Necessarily Good in Keeping a Healthy Gut, Find New Studies


Research published this week shows that over-the-counter probiotics don’t usually work, and in some cases, it can even do harm.

Probiotics have been considered to be “good bacteria” we find in food or supplements, and everyone thought it’s beneficial for the gut microbiome.

However, scientific evidence shows that probiotics are good only in some conditions.

The journal Cell has published two studies focusing on the effectiveness of over-the-counter probiotics in populating a healthy gut and how it helped a person’s gut recover after a treatment of antibiotics.

One of the two studies observed gut bacteria with upper endoscopies and colonoscopies. Researchers gave the study participants either commercial probiotics or placebo.

Eran Elinav is a researcher that authored both studies. He explains that they were all surprised to see how easy it was to divide the participants that took probiotics into two groups. One of the groups was called “resisters,” and the other “persisters.”

Elinav said that the group of “resisters” didn’t react to the bacteria at all:

“They were not doing anything to the human host. They were just failing to colonize.”

The “persisters” group had a change to the microbiome. This is how researchers learned how to predict if someone is a resister or a persister by measuring the microbiome before and after taking probiotics.

“Worse than not doing anything”

The second study focused on finding out how probiotics helped people get a normal gut microbiome after a course of antibiotics.

“It’s very widely practiced throughout the world, taking probiotics with antibiotics with the thought that they would protect against pathogenic infection after taking antibiotics,” Elinav said.

The team split the participants into three groups of people. One group received commercial probiotics, the second received a gut bacteria transplant of their own – the one before receiving antibiotics, and the third group received nothing.

Compared to the other study, when taking antibiotics, commercial probiotics colonized the gut better. But the research team also found that probiotics didn’t allow the original microbiome return to the previous healthy state:

“This was worse than not doing anything. It was significantly bad, and persistent,” said Elinav.

The group that received samples of their own gut bacteria had their normal microbiome back to normal in a few days.

Elinav concluded that: “rather than relying on the one-size-fits-all approach we need to move to a new paradigm: well-adjusted personal microbiome or signature combinations, tailored to the individual.”

Adelaide gastroenterologist Daniel Worthley read the two studies and finally concluded that the best way to support a healthy microbiome is to have a good diet:

“Fundamentally what is indisputable is having a balanced diet rich in vegetables, which helps to foster a healthy microbiome. It’s the cornerstone on which a healthy gut is built.”


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