ISAPP strives for clear postbiotic definition in emerging innovation “excitement”

25 Jan 2024 --- Postbiotics, predicted to be the next innovation wave in the biotics series, is hot on the agenda of the International Scientific Association for Probiotics and Prebiotics (ISAPP) as it forges an accurate definition that can be applied to products and regulation. We speak with the team from ISAPP following the publication of their perspective paper in Frontiers that sought to answer the industry’s most frequently asked questions (FAQs).

“The concept of postbiotics — the understanding that dead microbial cells or fragments can powerfully activate some of the same host pathways as living microbes — has fueled significant research excitement, and gives us the possibility of further elucidating some of the specific molecular interactions responsible for the benefits of microbes in human health,” Marla Cunningham, executive director of ISAPP, tells Nutrition Insight.

“The possibility of using non-viable microbial preparations in the place of live microbes for certain applications also provides potential commercial advantages — the prospect for improved stability across a range of food formats. For example, those with higher levels of moisture or exposed to higher temperatures, potential cost savings on stability overages or quality control processes. And the possibility of countering some of the safety concerns associated with novel microbial species or vulnerable populations.”

Innovation excitement
Due to the wide interest in the field, an appropriate definition of terms “becomes even more critical.” Common terminology is needed to build knowledge that allows scientists and other stakeholders to communicate clearly with one another. 

Several commercial products in Europe, North America and Asia already display the current definition for postbiotics — established by ISAPP in 2021 — prompting the association’s urgency for refinement and clarity on wording future claims. 

“Postbiotics are currently fueling significant excitement in scientific research and commercial innovation. The concept leverages our growing understanding of the mechanisms and mediators of host-microbial interactions,” says Cunningham.

The researchers provide further justification for the concept of postbiotics in their perspective paper, published in Frontiers and discuss the rationale behind the definition, the scope of what qualifies as a postbiotic and the implications for commercial postbiotic products.

Dr. Gabriel Vinderola, Ph.D., Instituto de Lactología Industrial, Argentina, tells us: “Some recent applications that have caught my attention are postbiotics for dry eye, postbiotics to heal skin wounds by preventing infections or postbiotics to manage stress during scholarly exams by acting on the microbiota-gut-brain axis.”

“So far, most products that potentially fit the ISAPP definition to be considered as postbiotics were developed as food supplements. However, some special foods, such as infant formula, have incorporated postbiotics as well.”

“The clinical trials performed with these products show their capacity to manage acute or antibiotic-associated diarrhea, to manage the symptoms of IBS, to boost immunity, to promote skin health, to manage infant colic and other benefits.”

Definition harmonizes the marketplace
According to the ISAPP scientists, postbiotics are one of the most misunderstood substances. Therefore, they are pushing for clarity on the concept by proposing a scientific consensus definition, “a preparation of inanimate microorganisms and their components that confers a health benefit on the host.” 

“The official definition states that postbiotics are a ‘preparation of inanimate microorganisms and their components that confers a health benefit on the host.’ Every aspect of the definition was thoroughly debated by the consensus group and the reasoning is carefully outlined in the original paper,” Dr. Colin Hill, Ph.D., APC Microbiome Ireland, University College Cork, tells us.

“The final postbiotic preparation must contain cellular biomass resulting from a deliberate inactivation step — so a postbiotic cannot be composed of metabolites alone or purified proteins. Paramount to the definition is that a postbiotic must confer a health benefit and that this benefit must be proven in a well-conducted trial.”

Discussions in scientific publications and conference sessions indicate the broader scientific community still needs to reach a consensus on the term’s meaning. One of the most misunderstood concepts is why microbially-produced metabolites do not qualify as postbiotics.
ISAPP broaches the subject of clearly defining postbiotics as industry innovation takes off. 

Dr. Mary Ellen Sanders, Ph.D. and consulting scientific advisor at ISAPP, tells us: “One implication is that the definition provides clear, well-considered parameters for what a postbiotic is. This promotes a harmonized marketplace. Marketers have an opportunity to adhere to the stipulated scientific principles so that consumers will be confident about the composition and health benefits associated with any product labeled as a ‘postbiotic.’”

The afterlife of microbes
The motivation behind the perspective paper was the volume of FAQs about postbiotics that arose in public debates, on social media or in personal communications. 

“We wanted to collect these common questions in one place and elaborate specific answers, hoping this would bring further clarity in the field,” explains Vinderola.

The most frequently raised issue is why microbially-produced metabolites, whether purified, in a complex mixture or produced within the gut, are not considered postbiotics. 

The ISAPP scientists are convinced that postbiotic — meaning “afterlife” — is most appropriately applied to preparations of non-viable microorganisms and their component structures. The category was previously referred to by many contrasting names, including heat-killed probiotics, tyndallized probiotics, para probiotics and ghost probiotics. 

While metabolites are present in many preparations of microorganisms, such as probiotics and postbiotics, isolated metabolites do not meet the criteria for a postbiotic and can often be referred to by their chemical names.

Similarly, most proclaimed probiotics today must be clearly defined because it does not reveal how many live bacteria are in the supplements nor provide the scientific literature to verify the health benefits. We sat down with experts from Yakult Nederland to gain deeper insights. 

By Inga de Jong