Reevaluating the hype: four bacterial metabolites under scrutiny.

With microbiome research being a fiercely contested playground in science, new data are being published at tremendous pace. The review at hand serves to critically revise four microbial metabolites widely applied in research: butyric acid, flagellin, lipoteichoic acid, and propionic acid. All four metabolites are physiologically present in healthy humans. Nevertheless, all four are likewise involved in pathologies ranging from cancer to mental retardation. Their inflammatory potential is equally friend and foe. The authors systematically analyze positive and negative attributes of the aforementioned substances, indicating chances and dangers with the use of pre- and probiotic therapeutics. Furthermore, the widespread actions of microbial metabolites on distinct organs and diseases are reconciled. Moreover, the review serves as critical discourse on scientific methods commonly employed in microbiome research and comparability as well as reproducibility issues arising thereof.