postbiotic

Postbiotic is a term used to describe bioactive compounds produced by or derived from microbial organisms that can confer health benefits to the host, without requiring live microorganisms. This distinguishes postbiotics from probiotics, which are live microorganisms, and from paraprobiotics, which refer to inactivated cells themselves. Definitions vary by organization and researcher, but many sources describe postbiotics as preparations containing inanimate microorganisms and/or their components, metabolites, or cellular fragments that exert biological effects.

The terminology has overlapping usage. Some definitions emphasize inanimate microbial cells and their components, such as cell wall fragments or enzymes, while others focus on metabolites produced by microorganisms, including short-chain fatty acids, organic acids, peptides, bacteriocins, and other bioactive molecules. Because the field is evolving, the term postbiotic can encompass both inactivated whole cells and non-cellular microbial products.

Examples of postbiotic components include heat-killed bacterial cells, bacterial lysates, extracellular polysaccharides, lipoteichoic acids, enzymes, and microbial metabolites like short-chain fatty acids and other signaling molecules. These components may influence host physiology through immune modulation, enhancement of gut barrier function, antimicrobial effects, and metabolic signaling.

Evidence for health benefits is growing but variable by product and condition. Postbiotics are used in foods, dietary supplements, infant formulas, and some therapeutic contexts, with regulatory definitions and allowable health claims differing across jurisdictions. Safety considerations emphasize non-viability reducing infection risk compared with live probiotics, though quality, source, and formulation remain important factors.