Understanding Probiotics, Prebiotics, Synbiotics, and Postbiotics: A Comprehensive Review of the Newest Definitions, Selected Strains and Products

In recent years the field of probiotics, prebiotics, synbiotics and postbiotics has been extensively studied. Preparations including live and inanimate microorganisms, their parts and substances that selectively stimulate their growth, are promising in treatment or amelioration of symptoms in many diseases. The aftermath of the COVID-19 pandemic has forced us to face complications such as post-acute COVID-19 syndrome and a general decrease in population immunity, for which treatment with probiotics, prebiotics, synbiotics and postbiotics is promising. The use of such preparations can have a positive effect on the immune system and has also shown positive effects in major depressive disorder. Due to the rapid development in the field a lot of confusion and misconceptions emerged, especially regarding the use of terms and definitions. This article aims to present a clear classification of these products according to International Scientific Association of Probiotics and Prebiotics (ISAPP) guidelines as well as basic mechanisms of action and efficacy of selected preparations. Authors of this article use the term ‘biotic(s)’ to refer collectively to probiotics, prebiotics, synbiotics and postbiotics. While this term has not been officially established, it is used by other authors in the scientific literature. The taxonomic nomenclature used in this article has been updated according to the most recent taxonomic reclassification.