postbiotics

Postbiotics are preparations of inanimate microorganisms and/or their components that confer health benefits to the host. Unlike probiotics, which are live microorganisms, postbiotics do not require viable cells to exert effects. They may include non-viable microbial cells (paraprobiotics), microbial cell wall fragments, and soluble metabolites such as enzymes, peptides, organic acids, and other bioactive compounds secreted by microbes.

Composition and examples: types include heat-killed bacterial cells, cell-free supernatants, and purified microbial metabolites. Common examples studied include inactivated Lactobacillus and Bifidobacterium preparations, bacteriocins, and short-chain fatty acids produced by gut microbes. Not all preparations labeled as postbiotics demonstrate identical activity; effects are product- and dose-dependent.

Potential mechanisms: postbiotics may modulate the host immune system, improve intestinal barrier function, exert antimicrobial effects against pathogens, and influence systemic metabolism via signaling pathways. Mechanisms often involve interactions with host pattern recognition receptors and signaling cascades.

Applications and regulation: used in functional foods, dietary supplements, and infant nutrition as alternatives or complements to probiotics. Regulatory definitions vary by jurisdiction; evidence from clinical trials is growing but heterogeneous, with some studies reporting benefits for gastroenteric health, allergy risk, and metabolic markers, while others show limited effects.

Safety and research status: generally considered safe when produced under quality controls, with lower risk of infection compared to live probiotics. However, safety assessments, standardization, and clear labeling remain important, and more high-quality randomized trials are needed to define efficacy, optimal formulations, and dosing.