Postbiotics: An Overview and Recommendations for Improved Reporting

Postbiotics, a term gaining traction among scientists and consumers, refers to nonviable microbial products or components that confer health benefits to the host. Despite their growing recognition, there is no generally accepted definition, with various interpretations and historically used terms around their physical nature, including intact dead cells, lysates, and intra- and extracellular metabolites. We review postbiotic research reporting practices, with special focus on clinical studies. Postbiotics demonstrate superior stability, extended shelf life, and broader applicability compared to probiotics. Nevertheless, they are susceptible to oxidative or enzymatic degradation, can be potentially allergenic, and may harbor DNA with transferable antibiotic resistance genes. We identified 101 clinical studies on postbiotics. Not included in this are studies on yeast β-glucan (estimated at least 34 studies). Most studies reported on the use of products obtained from single strains, only 12 studies investigated mixed-strain preparations and heat-treated yogurt. For inactivation, heat-treatment was reported by 69 studies. There was substantial variation in temperatures: 70-140°C, and duration: 4s to 10 h. Postbiotic study reporting is diverse and should improve. We suggest the following recommendations: reporting proper taxonomy of source organism, using proper terminology of inactivation method and provide method details, report administered quantity, provide information on quality control.