Overview
Postbiotics are defined by ISAPP (2021) as "preparations of inanimate microorganisms and/or their components that confer a health benefit on the host." They include heat-killed bacteria, cell-free supernatants, bacterial lysates, and purified microbial metabolites (SCFAs, bacteriocins, exopolysaccharides). Postbiotics offer the functional benefits of probiotics without the risks of live organism administration — relevant for immunocompromised patients, neonates, and conditions where live bacteria could cause bacteremia.
Advantages
- Safety: No risk of bacteremia or fungemia from live organisms.
- Stability: Heat-stable; no cold chain required.
- Standardization: Defined composition unlike variable live cultures.
- Mechanistic clarity: Specific metabolites can be dosed precisely.
Key Postbiotic Types
- short chain fatty acids: Butyrate, propionate, acetate — the most studied postbiotic class.
- Bacteriocins: Antimicrobial peptides (nisin, plantaricin) for targeted pathogen suppression.
- Exopolysaccharides (EPS): Immunomodulatory polymers.
- Cell wall components: Lipoteichoic acid, peptidoglycan fragments — TLR ligands for immune training.
Cross-References
- prebiotics — substrate for live microbial postbiotic production
- synbiotic — live probiotic + prebiotic combination (distinct from postbiotic)
- short chain fatty acids — primary postbiotic metabolite class
- metabolites — broader microbial metabolite context