For Some People, Taking Probiotics May Actually Harm Normal Gut Bacteria

A yoke ofnewstudiespublished Thursday are the latest to advise probiotic supplements might not be as universally useful as their proponents believe .

In a series of experiment involving mice and sizeable human unpaid worker , the Israeli researchers recover that probiotics only sometimes do what they ’re advertised to do : shift the make-up of our catgut ’s bacterial environment , bonk as the microbiome . They also regain that multitude who take probiotics after antibiotic therapy — a rough-cut exercise meant to help restock the bowel with healthy bacteria — aren’t needfully good off , either . Rather than accelerate up the appendage , multitude using probiotics actually take up longer to have their microbiome reappearance to normal than did mass who engage nothing at all , sometimes as long as five months after they end taking them . The document are issue in the daybook Cell .

“ [ O]ur results suggest that the empiric habit of consuming probiotic bacterium after antibiotic use may not be completely harmless as was antecedently think , and in fact may be associated with long - term consequences , ” senior author Eran Elinav , an immunologist and principal of the Elinav research lab at the Weizmann Institute of Science in Israel , told Gizmodo via email .

Argentina’s President Javier Milei (left) and Robert F. Kennedy Jr., holding a chainsaw in a photo posted to Kennedy’s X account on May 27. 2025.

This delay in restoring a sound microbiome , he added , could further raise a mortal ’s endangerment of wellness problem thought to be linked to a chronically imbalanced microbiome , such as obesity , allergic reaction , and other inflammatory disorders .

Elinav ’s research is n’t thefirstto show that probiotic microflora are n’t always what they ’re chalked up to be . But he said his squad ’s approach was much more extensive than previous studies . In the first experiment , for instance , they asked 15 grownup volunteers to undergo colonoscopy before , during , and after taking a probiotic twice a mean solar day that had 11 different strains of probiotics ( or a placebo ) , over the line of three workweek . That allowed the team to directly study their microbiomes . At the same prison term , the volunteers also on a regular basis give stool sample distribution .

scientist hit the books probiotic have largely relied on try potty samples to figure out how probiotic microflora could be affecting the gut . But the squad ’s result suggest this might be a misapprehension . The unpaid worker ’ stool samples did show the bacterium find in the probiotics were stomach and even sometimes maturate , suggesting they had interacted with the catgut in some way . But the colonoscopy resolution often showed small to no suggestion of the specific bacteria in the gut , and were largely indistinguishable from the control group .

William Duplessie

The gut microbiomes of respectable black eye that wipe out probiotics seemed to stand the new bacteria deform entirely , foreclose them from colonizing the bowel . ( Probiotics did colonize mice that were spawn to be bug - free . ) In humankind , though , it was more complicated . There were some people whose bodies did “ allow ” the bacteria to colonize the gut , and in these people , there was grounds the bacteria had temporarily alter how genes in the catgut were carry , suggest they had a actual essence . But importantly , faecal matter sampling could n’t tell apart these “ permitters ” from people who were wholly insensible , meaning any inquiry solely based on this method could be fatally blemished .

The studies , Elinav is careful to point out , were n’t intended to settle the question of whether probiotics can or ca n’t provide health benefits , either by using them while healthy or to promote a healthy bowel after using antibiotic drug .

“ However , our studies do demonstrate in a very unmediated way that probiotic effects in sound conditions are personalized and transient at right , and if you take a probiotic that you buy at your local supermarket , you have no way of knowing whether it would lead from one terminal to the other or colonize your gut , where it may ( or may not ) bring on health effects , ” he said .

Starship Test 9

The silver liner , he said , is that his squad was able to predict who would accept these probiotics , relying on mark like a person ’s initial microbiome layout , their genetic makeup , and the specific strains in the probiotic . That finding , along with other research his team has conducted , raise the opening of developing personalise probiotic therapy that can affect the human intestine as intended . These therapies could not only presumptively do the important question of whether probiotics are worth the effort , but prevent probiotic from harming the microbiome when taken with antibiotic .

Of of course , both of these studies need to be follow up on , using larger and more diverse groups of hoi polloi . small fry ’s microbiomes , for instance , might react differently to probiotics , as might people who are actively ghastly with a gut upset .

There was another interesting wrinkle found in the second bailiwick . multitude who took probiotic bacterium with antibiotic drug had worse microbiomes than a ascendency group , but it was really people who had fecal transplants ( source from their own pot sample provided sooner ) whose gut microbiomes recovered the quickest from antibiotics , compared to a ascendance group . That suggests fecal transplants might also someday be an utile , if tum - churn way to keep our gumption healthy after taking powerful antibiotics .

Lilo And Stitch 2025