Full Studies:

• N Zmora et al. Personalized Gut Mucosal Colonization Resistance to Empiric Probiotics Is Associated with Unique Host and Microbiome Features. Cell; 174: 1388-1405

• J Suez et al. Post-Antibiotic Gut Mucosal Microbiome Reconstitution Is Impaired by Probiotics and Improved by Autologous FMT. Cell 2018; 174: 1406-1423.

The coverage of these studies in the media has created some controversy; enough so that the International Scientific Association of Probiotics and Prebiotics disseminated a very critical review:

CLINICAL EVIDENCE AND NOT MICROBIOTA OUTCOMES DRIVE VALUE OF PROBIOTICS

Here is a small excerpt:

Two recent papers have generated much adverse publicity for the probiotic field. Headlines driven by sensationalism, not data, claim “Probiotics labelled ‘quite useless’” (BBC) and “Probiotics ‘not as beneficial for gut health as previously thought’” (The Guardian). The quotes are from author Eran Elinav, who generalizes the study findings to all ‘probiotics’ as a class – a generalization that ignores that specific probiotic are meant for specific purposes…

The scope of these papers is limited to microbiome data; no clinical endpoints are assessed. Without clinical evidence, it is not possible to conclude about the tested probiotic’s usefulness, and it is certainly not possible to conclude about probiotic usefulness in general…. The authors discount the existing body of evidence for probiotic health benefits, including Level 1 placebo-controlled, randomized trials. Cochrane reviews (the gold standard used by physicians and public health policy makers) of the totality of evidence show that specific probiotics can prevent antibiotic associated diarrhea (AAD) and C. difficile diarrhea. This evidence has been translated into evidence-based recommendations for probiotics issued by medical groups. Regardless of an effect on the microbiota, these are established, evidence-based benefits of probiotics.

My take: This controversy points to the problem that probiotics are often considered more effective than the science merits.  While there are some conditions that may respond to probiotics, it should be understood that each probiotic needs to be looked at for each specific clinical scenario.

Related blog posts:

• Probiotics for Prevention of Nosocomial Diarrhea
• The Truth About Probiotics -Constipation Version
• How Good is Your Probiotic for Antibiotic-Associated Diarrhea
• “Low quality of evidence; strong recommendation” for Probiotics in Gastroenteritis
• How helpful are probiotics?