Prebiotics, Probiotics, and Postbiotics: a synergistic connection

Understanding the differences between the key player of your health

Prebiotics, probiotics, and postbiotics work in synergy to support intestinal health. However, it’s important not to confuse them, so let’s take a closer look into their individual contributions!

Prebiotics: the feeding

The International Scientific Association of Probiotics and Prebiotics (ISAPP) defines dietary prebiotics as “a substrate that is selectively utilized by host microorganisms conferring a health benefit”.

Specifically, prebiotics are fibers such as inulin, fructooligosaccharides (FOS), and galactooligosaccharides (GOS), commonly found in fiber-rich foods, like fruits, vegetables, whole grains, and legumes. They are non-digestible by human enzymes, so they reach the colon intact where they are fermented by the beneficial gut bacteria to produce energy, which supports their growth and proper functioning.

Thus, prebiotics selectively reduce the abundance of pathogenic bacteria, and help to maintain a balanced gut microbiota.

Probiotics: the manufacturers

In 2001, the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) agreed on a definition for probiotics: “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host“.

Probiotics primarily include bacteria belonging to the genera Lactobacillus and Bifidobacterium, and yeasts, such as Saccharomyces boulardii.

After ingestion, probiotics colonize the intestine and cooperate to maintain or restore gut eubiosis. The intricate mechanisms involving probiotics are strain-specific. However, common actions include the rebalancing gut microbiota composition, the competition with pathogens for nutrients and binding sites, the enhancement of intestinal barrier function, and finally the modulation of the immune system.


Postbiotics: the precious yield

In 2021, ISAPP defined postbiotics as “inanimate microorganisms and/or their components that confer a health benefit on the host”. Tipically, they include a wide range of molecules, such as cell wall components, inactivated cells, or short-chain fatty acids (SCFAs), peptides, polysaccharides, vitamins, and organic acids (e.g. lactic acid) generated through probiotic metabolism. Since postbiotics are a heterogeneous group of components, there is a significant debate within the scientific community about the differentiation among intact cells, fragments or molecules, therefore creating additional subclasses.

The precise composition of postbiotics, is influenced by the specific probiotic strain used, the growth conditions, and the substrates available for fermentation.

Postbiotics exert their beneficial effects acting as signaling molecules and influencing host metabolism and also inhibiting the growth of harmful bacteria. Finally, they exhibit anti-inflammatory and anti-oxidant properties, improving the immune response.

In summary, probiotics are live good microorganisms, prebiotics are food for these microbes, and postbiotics are the byproduct released. Each one participates differently in the relationship with the human host and significantly contributes to overall health and well-being.


Ji, Jing et al. “Probiotics, prebiotics, and postbiotics in health and disease.” MedComm vol. 4,6 e420. 4 Nov. 2023, doi:10.1002/mco2.420

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