Researchers Raise Doubts About the Benefits of Probiotics

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Millions of people use probiotic supplements to enhance their digestive health and counterbalance the effects of antibiotics in the GI (gastrointestinal) tract. But are probiotics beneficial? Maybe not.

Results of two small studies conducted at the Weizmann Institute of Science in Israel and the Tel Aviv Medical Center suggest that the human gut often prevents standard probiotics from colonizing the digestive tract successfully, and that taking probiotics with antibiotics can delay the return to normal gut bacteria and gene expression.

The first study involved 15 volunteers who underwent upper endoscopies and colonoscopies to sample their baseline gut microbiome and then were divided into two groups, one that received a generic probiotic and one that received a placebo. After two months, both groups had additional upper endoscopies and colonoscopies to assess the response in their gut microbiome. According to the researchers, the probiotics successfully colonized the GI tracts of some study participants (called "persisters") but were expelled by the gut microbiome in others (called "resisters").

In the second study, the researchers gave 21 volunteers a course of antibiotics and then randomly assigned them to one of three groups: a watch-and-wait group that didn’t take anything additional and allowed their gut microbiome to recover from the antibiotics on its own; a group that took the same generic probiotic used in the first study; and a group that was treated with a fecal transplant consisting of bacteria collected from their GI tract before they took the antibiotic.

The researchers found that standard probiotics colonized the digestive tract easily in the second group, but the colonization prevented the normal microbiome and gut gene expression profile from returning to normal for months. In the fecal transplant group, the gut microbiome and gene expression profile returned to normal within days.

Sourced from: Cell