The potential of paraprobiotics and postbiotics to modulate the immune system: A Review

Probiotics are viable microorganisms that provide beneficial health effects when consumed in adequate quantity by the host. Immunomodulation is one of the major beneficial effects of probiotics that is a result of the colonization of probiotic microorganisms in the gut, their interaction with the intestinal cells, production of various metabolites and by-products. The last few years have displayed an increasing number of studies on non-viable probiotics (paraprobiotics) and microbial by-products (postbiotics) that prove beneficial to human health by providing positive immune responses even in the inactivated form. The increasing number of research studies compare the effects of viable and non-viable probiotics, their by-products, and metabolites. This review focuses on the ability of different types of paraprobiotics and postbiotics to modulate the immune system. A majority of paraprobiotics are developed from Lactobacillus and Bifidobacterium strains. The postbiotic components that modulate the biological reactions include lipoteichoic acids, bacteriocins, short-chain fatty acids, peptidoglycan, and exopolysaccharides have been reported. We have reviewed paraprobiotics and postbiotics that are commercial as well as in research. Paraprobiotics and postbiotics can be a possible replacement for live probiotics for immunocompromised people. Paraprobiotics display an active role in maintaining T-cell mediated immunity and have been shown to treat colitis. Postbiotic components exhibit properties of pro and anti-immune, anti-tumor, anti-microbial, antioxidant, and anti-biofilm. More research is required on the efficient conversion of probiotics to paraprobiotics, the isolation and purification of different postbiotics, and stability studies during the shelf life. The majority of the articles report the effects of direct ingestion of different '-biotics' without blending in any food product.