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Every day, millions of people take probiotics – preparations containing live bacteria to strengthen their immune system, prevent disease or repair the side effects of antibiotics. Yet the benefits of probiotics have never been clinically proven.
Researchers at the Weizmann Institute of Science in Israel are now presenting experiments in mice and humans that the most used probiotics may be less than beneficial.
According to two consecutive reports published on September 6 in the journal Cellit is not even clear if the probiotic bacteria actually colonize the digestive tract or, if so, how they affect the microbiome of native intestinal bacteria.
For the first study, 25 human volunteers underwent superior endoscopy and colonoscopy to sample their basal composition and function in different intestinal regions. Fifteen of these volunteers were then divided into two groups: one receiving a probiotic preparation with 11 strains and the second receiving placebo tablets.
Graphic of "customary intestinal mucosal colonization resistance to empirical probiotics is associated with unique characteristics of the host and microbiome," Cell, September 6, 2018.
Three weeks after the four-week treatment, all participants underwent a second upper endoscopy and colonoscopy to assess their response to probiotics or placebo, followed by an additional two months of follow-up.
The researchers found that intestinal colonization of probiotics was very individual. In general, there were "persistent" whose bowels harbored the probiotic microbes and the "resistant" who expelled them.
Scientists have discovered that they can predict whether a person would be a patient or a resistant simply by examining the basic microbiome and the gene expression profile of the host. The perselles showed changes in their gene expression profile of the microbiome and the intestine, whereas the resistances did not undergo such changes.
The two-part study was led by researchers from Professor Eran Elinav's laboratories of the Department of Immunology and Professor Eran Segal from the Department of Computer Science and Applied Mathematics, in collaboration with Professor Zamir Halpern , head of gastroenterology in Tel Aviv Sourasky. Medical Center.
"Our results suggest that probiotics should not be universally given to the public as a single supplement," Elinav said. "Instead, they could be tailored to each individual and their particular needs. Our results even suggest how such customization could be achieved.
Segal said the results reinforce earlier studies on diet that revealed a similar individual response to foods and "highlighted the role of the gut microbiome in determining very specific clinical differences between people".
Probiotics after antibiotics may not work
In the second study, researchers tested the wisdom of counseling largely given to people to take probiotics to counteract the effects of antibiotics.
They investigated whether probiotics colonized the gut after antibiotic treatment and how this affected the human host and its microbiome.
The researchers administered broad-spectrum antibiotics to 21 human volunteers, who then underwent superior endoscopy and colonoscopy to observe changes in the intestine and its microbiome after antibiotic treatment.
Then the volunteers were randomly assigned to one of the three groups. The first was a surveillance group that allowed its microbiome to recover on its own. The second group received the probiotic cocktail with 11 strains over a period of four weeks. The third group was treated with an autologous faecal microbiome transplant (aFMT), consisting of its own bacteria collected before taking the antibiotic.
Scientists have discovered that the antibiotic paves the way for probiotics and that they colonize the human intestine much more easily than in the previous study.
To their surprise, this was not beneficial: probiotic colonization prevented gene expression and the microbiome from returning to normal pre-antibiotic patterns for months.
In patients treated with aFMT, the pattern of recolonization of the native gut microbiome and the gut gene returned to normal within a few days.
Graphic of "The reconstitution of the mucosal microbiome of the post-antibiotic gut is altered by probiotics and enhanced by autologous FMT," Cell, September 6, 2018.
"These results," said Elinav, "reveal a potentially alarming new negative side effect of using probiotics with antibiotics that could even have long-term consequences.In contrast, a personalized treatment – replenish the intestine with its own microbes – has been associated with a complete reversal of the effects of drugs. "
Since probiotics are among the best-selling OTC supplements in the world, these results can have immediate and significant implications.
"Contrary to current dogmas, probiotics are harmless and benefit everyone," said Segal, "we suggest that probiotic preparations should be tailored to individuals, or that such treatments as autologous FMT may be indicated in certain cases.
Dr. Niv Zmora, Dr. Jotham Suez, Dr. Gili Zilberman-Schapira and Dr. Uria Mor from Elinav's laboratory led both projects, together with other members of the Elinav and Segal lab, as well as with scientists and clinicians from Weizmann and Tel Aviv Sourasky. Medical Center, Tel Hai University and Galilée MIGAL Institute .Segal is head of the Weizmann Institute's Crown Human Genome Center.
the Cell the reports can be viewed here and here.
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