Experts publish first global framework for quantifying postbiotics

Postbiotics are a quickly-growing category of products targeting gut health and other applications, such as skin. Defined in 2021 as “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”, postbiotics differ from probiotics in that they are not alive when administered.

Despite the growing interest in postbiotics across academia and industry, scientists have not aligned on how to address the complexity of quantifying postbiotic products. Proper quantification is essential for measuring the dose of a postbiotic and ensuring consistency across scientific studies, but there is not yet a gold standard for postbiotic quantification—in contrast with probiotics, which are quantified using colony forming units (CFU).

A group of 15 leading scientists from academia and industry have now published a paper that provides practical guidance on postbiotic quantification that can be implemented worldwide. The paper, called “Postbiotics: a perspective on their quantification”, appeared in Frontiers in Nutrition and originated from a 2024 expert working group held by ISAPP, the International Scientific Association for Probiotics and Prebiotics.

Rather than presenting a rigid set of rules, the publication provides a decision tree to assist in the selection of the most appropriate quantification techniques—depending on the type of microorganisms, cell integrity, and number of strains present—to ensure that postbiotic products are accurately characterized and can be reproducibly manufactured. Because postbiotic mixtures may contain complex mixtures of dead cells, cell fragments, and metabolites, full characterization and quantification of all components may not be possible but researchers can focus on key components of the mixture to ensure consistency from batch to batch.

“After publishing the postbiotic definition in 2021, we realized from discussions with other scientists that a harmonized framework for postbiotic quantification was needed for the field to move forward,” says first author Dr. Gabriel Vinderola PhD of National University of Littoral & CONICET in Argentina. “We hope this publication will help researchers, regulators, and manufacturers become more aligned on how to quantify many different kinds of postbiotics.”

For industry scientists, the paper presents a selection of up-to-date technical strategies that will serve to guide the most appropriate technological approach for the quantification of components in their particular product. It also highlights how future developments in fields such as flow cytometry and PCR will meet industry needs.

The authors emphasize that best practices for postbiotic quantification will likely evolve as laboratory technologies and methods improve over time. However, the paper provides an important initial framework that can support the continued development of postbiotic products globally.