Probiotics are live microorganisms which, when administered in adequate amounts, support specific changes in GI microbiota to favor beneficial bacteria. In addition to effects on commensal microbiota, probiotic benefits include modulation of immune or sensory-motor function, enhancement of mucosal barrier function, and antipathogen effects. Clinical trials in humans have examined therapeutic efficacy of probiotics in several gastroenterologic disorders, and their use is considered safe in most populations. While controversy exists, evidence supports probiotic use in some (eg, acute onset infectious diarrhea, pouchitis, ulcerative colitis, irritable bowel syndrome (IBS), non-Clostridium difficile–related antibiotic-associated diarrhea), but not all (eg, chronic liver disease–associated conditions, Crohn’s disease, C difficile–associated diarrhea), of gastroenterologic conditions. This review discussed condition-specific rationale for probiotic use with literature-based recommendations. The mechanisms by which probiotics exert their benefits vary with specific strains and likely depend on clinical indication. Strains and dosages should be matched with the condition for which the probiotic has shown benefit in clinical trials, and selection should focus on quality-tested products with clinically demonstrated benefit for the given disorder.

Commentary
Most readers will have heard of probiotics and used them in their patients, but I suspect few really understand their actions and indications. The same might be said for many of our colleagues in human medicine, with probiotics often recommended for conditions in which there is no indication. The excellent mini-review of the veterinary use of probiotics by Dr. Ridgway should help readers understand more about their indications and use; I strongly recommend this.

Related Article: Probiotics

However, if more information is needed, especially information on indications and use in humans, then I recommend this article by Dr. Ciorba. It contains fascinating facts about the human microbiome, provides a figure that summarizes the mechanism of action of probiotics, puts yogurt into perspective as a putative probiotic (depending on type, source, and number of lactobacillus organisms), and reviews specific GI indications for probiotic use in humans. Of particular interest is the table listing all known US commercial probiotics available for GI disorders, their relative price, bacterial types and numbers, and effectiveness in clinical trials.

All probiotics are not created equal; I wish we had similar data for our veterinary patients.—Colin F. Burrows, BVetMed, PhD, Hon FRCVS, DACVIM

Source
Perspectives in clinical gastroenterology and hepatology: A gastroenterologist’s guide to probiotics. Ciorba MA. CLIN GASTROENTEROL HEPATOL 10:960-968, 2012.

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