What are
postbiotics?

Although the concept of postbiotics has been known for over a decade, its definition was still under debate. In a recent publication, the International Scientific Association of Probiotics and Prebiotics (ISAPP), has clarified its definition as following: “A preparation of inanimate microorganisms and/or their components that confers a health benefit on the hosts1“. This definition formalizes the idea that non-living microorganisms can promote or maintain health.
According to this definition, as long as they have demonstrated beneficial effects on health, postbiotics can either be:
  • Intact inanimate microorganisms
  • And/or fragments or structures of inactivated microorganisms
  • With or without compounds from culture medium or produced by microorganisms, called metabolites.

Components of postbiotics:

To obtain such a preparation and have the right to call it postbiotic, it must meet several criteria:

Safety:

  • Guaranteed positive safety profile for the user under the recommended conditions of use

Detailed composition:

  • A detailed description of the composition of the postbiotics

Inertness:

  • A precise description of the process to obtain inanimate bacteria
  • A proof of inactivation of the bacteria

Efficiency:

  • The beneficial effects on the host must be scientifically demonstrated.
To sum up, “postbiotics” only refer to specific preparations, which include the description of the microorganisms, the inactivation procedure and the other compounds that had contributed to a demonstrated health benefit.

How are they made? ​

Fermentation

The first step in the production of postbiotics is fermentation. The goal is to let the living bacteria grow and produce a maximum of compounds of interest.

Collection

Bacteria and compounds are then collected, they will be the basis for the rest of the process.

Inactivation

Inactivation is the key step in postbiotics manufacturing. Different processes can be used:

  • The most classic is inactivation by heat-treatment. It has been used for centuries to inactivate microorganisms. We can cite the well-known examples of pasteurization and sterilization which are used daily for the preservation of our food.
  • Other types of treatments can also be used to inactivate bacterial strains for postbiotic purposes. To name but a few, we can mention pulsed light or high pressure.
Are postbiotics natural? To answer this question, let’s recap the manufacturing process: let some bacteria grow, inactivate them by a thermal or mechanical treatment. Nothing chemical then!

How do postbiotics work?

To confer a beneficial effect on health, postbiotics have several modes of action. In interaction with both the microbiota and the intestinal cells, there are many possibilities, let’s take a closer look.
Protective role of the intestinal barrier: role of protective barrier against the external elements that could be dangerous.
Positive effects on metabolism: the word metabolism gathers all the mechanisms that allow our body to work properly.

What are the advantages of postbiotics?

Health benefits

More and more studies demonstrate the health benefits of postbiotics. Postbiotics have been studied in the prevention and treatment contexts: reduction of symptoms in patients with irritable bowel syndrome2, reduction of the duration of diarrhea, etc. Most of the research is conducted in the medical field for therapeutic applications, but postbiotics could also have nutritional benefits.

Convenience

As they are inanimate, postbiotics strains do not have the same storage and stability concerns as probiotics. Indeed, since probiotics contain living bacteria, strict storage conditions must be respected for most of the strains because they are sensitive to heat and oxygen. It is a real issue in certain regions of the world where it is difficult to maintain the cold chain from the moment the probiotics are produced to the moment they are consumed. A problem that could be solved with postbiotics!

Safety

Moreover, postbiotics are reliable in terms of safety. They are not expected to pass into the bloodstream through the intestinal barrier. Thus, they are unlikely to cause bacteriemia or fungaemia. Likewise, postbiotics cannot cause antibiotic resistance. This positive safety record makes postbiotics suitable for both adults and children.

Where to find postbiotics?

Functional foods and beverages

Drugs

Food supplements

1.Salminen, S., Collado, M.C., Endo, A. et al. The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nat Rev Gastroenterol Hepatol (2021). https://doi.org/10.1038/s41575-021-00440-6

2.Tarrerias, A L et al. “The effect of inactivated Lactobacillus LB fermented culture medium on symptom severity: observational investigation in 297 patients with diarrhea-predominant irritable bowel syndrome.” Digestive diseases (Basel, Switzerland) vol. 29,6 (2011): 588-91. doi:10.1159/000332987