Paraprobiotics and postbiotics: from mechanistic evidence to food applications and clinical translation

Abstract

Interest in non-viable microbial preparations has increased as an alternative to selected technological and safety limitations of live probiotics. Paraprobiotics generally comprise non-viable intact or fragmented microbial cells, whereas the International Scientific Association for Probiotics and Prebiotics (ISAPP) definition of a postbiotic requires a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host. This review critically evaluates mechanisms, clinical evidence, food applications, manufacturing, regulation, and future research priorities. Non-viable microbial preparations can modulate host responses through cell-associated structures, including peptidoglycan, lipoteichoic acids, surface proteins, and exopolysaccharides (EPS), while microbial-derived metabolites such as short-chain fatty acids contribute to barrier and host–microbiota signaling; isolated metabolites, however, should not automatically be classified as postbiotics. Clinical evidence remains preparation- and indication-specific, with stronger evidence for selected preparations such as heat-inactivated Bifidobacterium bifidum MIMBb75 in irritable bowel syndrome (IBS) and more limited or predominantly preclinical evidence for other indications. In food systems, effects on stability, texture, microbial quality, sensory acceptance, and functionality depend on strain, processing, concentration, and matrix. Key barriers include inconsistent terminology, variable inactivation procedures, incomplete characterization, non-standardized dosing, limited long-term clinical evidence, and fragmented regulation. Progress will require reproducible manufacturing, verified residual non-viability, molecular characterization, potency markers, standardized dose reporting, and preparation-specific clinical validation.