Do probiotics really promote gut health? Two new studies reveal that the answer is not as simple as yes or no.

Two New Studies On Probiotics

Many people swear by the positive effects of probiotics, but do they really help promote gut health or even affect it? Researchers conducted two thorough studies to see just how probiotics affect gut microbiome, and the results show that the supposed benefits aren’t straightforward as they appear to be.

For both studies, researchers ensured that the generic probiotic products they used really contained the claimed 11 strains of beneficial bacteria strains.

‘Persisters’ And ‘Resisters’

In their first study, researchers gathered 15 volunteers who were willing to undergo endoscopies and colonoscopies, of whom some were given probiotics and the others placebo. The procedures were conducted at baseline and again two months after consuming the probiotics or the placebo.

Results show that among the participants, some were “persisters” while others were “resisters.” The persisters were the ones whose guts were successfully colonized by the generic probiotic bacteria, while the resisters were the ones who expelled the generic probiotics before they could even be established.

Researchers believe that there may be two reasons behind the persistent and resistant reactions. For one thing, each person has a unique gut microbiome that could either accept or reject the establishment of the generic probiotics. This was established by a mice study in which the same reactions were found among the germ-free mice injected with the persistent and resistant microbiota.

A second reason behind the difference in reactions to the generic probiotics could be the participants’ gene expression profile. Evidently, even before the probiotics were administered, researchers found that those who ended up resisting the probiotics had a unique gene signature that essentially gave them a more activated autoimmune response compared to those who were found to be more permissive to the probiotics.

Basically, not everyone has the same response to probiotics, with some being more permissive to the establishment of new bacteria, while others may naturally reject them.

Post-Antibiotic Impairment

In a second study, researchers wanted to see how probiotics would affect the gut microbiome after taking a course of antibiotics that kill bacteria. Twenty-one volunteers were given standard antibiotics for seven days, simulating the typical dosage given for the treatment of Crohn’s disease and diverticulitis.

The patients were then separated into three groups: one group recovered naturally, the second group took generic probiotics, while members of the third group were administered with an autologous fecal microbiome transplant (aFMT) in which they were given a healthy dose of their own microbiome.

Interestingly, the microbiomes of the participants in the group that got the aFMT recovered and returned to normal in just a few days, while the generic probiotics successfully colonized the gut of those in the probiotic group, possibly because the antibiotics wiped out the natural gut bacteria.

However, the probiotics prevented the re-establishment of natural gut microbiome. Even six months after the treatment, the participants’ gut microbiome still had not returned to normal, suggesting that the probiotics are not a good replacement to the natural gut bacteria, which has a wider diversity.

Not One-Size-Fits-All

While the results of the studies did not show any directly harmful effects as a result of consuming probiotics, the two studies published in the journal Cell show that when it comes to probiotics, a one-size-fits-all approach just won’t cut it, as there are many factors that can affect the efficacy of the supplement.

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