Consumption of probiotic products continues to increase, perhaps driven by an interest in gut health. However, the field is filled with controversy, inconsistencies, misuse of terminology, and poor communication. While the probiotic concept is biologically plausible and in some cases mechanistically well established, extrapolation of preclinical results to humans has seldom been proven in well-conducted clinical trials. With noteworthy exceptions, clinical guidance has often been derived not from large, adequately powered clinical trials but rather from comparisons of disparate, small studies with insufficient power to identify the optimal strain. The separation of probiotics from live biotherapeutic products has brought some clarity from a regulatory perspective, but in both cases, consumers should expect scientific rigor and strong supporting evidence for health claims.
Keywords: Clostridioides difficile–associated disease; antibiotic-associated diarrhea; clinical trials; microbiome; necrotizing enterocolitis; probiotics.