Many living microorganisms have been deemed probiotics because of the health benefits they exert when introduced to the human microbiome – however, plenty of non-living microbes, and some of their byproducts, have apparent health effects, as well. Many of these organisms, no longer viable, are considered by researchers to fit into a new category called ‘postbiotics.’
 
Still, the category is not very well defined, and often, ‘postbiotics’ is a term used interchangeably with others, in varying contexts. However, the International Scientific Association for Probiotics and Prebiotics (ISAPP) has published a consensus definition of ‘postbiotics’ – “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host.”
 
This definition states that in order to fit the ‘postbiotics’ bill, products can include either whole microbial cells or components of the cells, as long as they have somehow been deliberately inactivated.
 
The group of experts in ISAPP, whose experience spans probiotics, postbiotics, adult and pediatric gastroenterology, pediatrics, metabolomics,, regulatory affairs, microbiology, functional genomics, cellular physiology, and immunology, wanted to clarify that postbiotics are a more nuanced concept beyond a common idea that they are just ‘heat-killed probiotics.’
 
“With this definition of postbiotics, we wanted to acknowledge that different live microorganisms respond to different methods of inactivation,” Professor Seppo Salminen, lead author of the publication, said. “Furthermore, we used the word ‘inanimate’ in favor of words such as ‘killed’ or ‘inert’ because the latter could suggest the products had no biological activity.”
 
Furthermore, the authors emphasize that a postbiotic does not need to be derived from a microorganism that is probiotic while animate. That is, a live precursor organism doesn’t need to have a benefit itself before it is used to create a postbiotic.
 
The consensus definition of ‘postbiotics’ was discussed at a panel convened by the International Scientific Association for Probiotics and Prebiotics in late 2019. This published definition is the latest in a series of international consensus definitions by ISAPP which expand upon probiotics, prebiotics, synbiotics, fermented foods, and, now, postbiotics.
 
“This was a challenging definition to settle. There are some who think that any purified component from microbial growth should be considered to be a postbiotic, but the panel clearly felt that purified, microbe-derived substances, for example, butyrate or any antibiotic, should just be called by their chemical names,” Mary Ellen Sanders, ISAPP’s Executive Science Officer, said. “We are confident we captured the essential elements of the postbiotic concept, allowing for many innovative products in this category in the years ahead.”
 
Postbiotics have long been available on the market in Japan, and fermented infant formulas which contain postbiotics are commercially available in South America, the Middle East, and some European Countries. Applications are likely to expand quickly with a groundswell of scientific research into their health benefits, ISAPP reports.
 
“The definition will be a touchstone for scientists, both in academia and industry, as they work to develop products that will benefit host health in new ways,” Sanders said. “We hope this clarified definition will be embraced by all stakeholders, so that when the term ‘postbiotics’ is used on a product, consumers will know what to expect.
 
Commentary
 
Some industry stakeholders expressed support for the consensus definition reached by ISAPP, considering it an important stepping stone in the establishment of this emerging category in the microbiome space.
 
“We believe postbiotic ingredients hold great potential and can bring health-supportive benefits to a wide range of foods, beverages, and supplements,” Dr. Justin Green, PhD, director of scientific affairs for Cargill Health Technologies, said. “Having an internationally-recognized definition is an important step, especially as this emerging class of ingredients gain mainstream recognition. Our hope is this common vocabulary and scientific framework sets the stage for greater research and product innovation into the postbiotic space, and we look forward to partnering with our customers and the industry at large on this journey.”
 
Stratum Nutrition, the supplier of a postbiotic ingredient branded as LBiome (human strain-derived, heat-treated Lactobacillus LB) recently shared the history of research which contributed to the discovery and implementation of postbiotics, of which Lactobacillus LB was a major component of as a subject of research for over a century, with 12 published human clinical studies backing its digestive health benefits.
 
The research pursuit of beneficial bacteria could be traced back to a Russian-born scientist, Elie Metchnikoff, who developed an interest in the study of beneficial microbes, working under a theory that the aging process could be significantly effected by the presence of both “bad” and “good” bacteria, investigating how certain beneficial bacteria could prevent the harmful overgrowth of certain harmful bacterial strains within the GI tract, eventually leading today’s industry to refer to him as the “Founding Father of Probiotics.”
 
100 years later, scientists began a pursuit to sequence the entire human genome, in what was known as the Human Genome Project. The estimated $3 billion development of the technology was then used in more recent attempts to sequence the entire human microbiome, in what was called the Human Microbiome Project, which has since resulted in the publication of over 350 studies. This was viewed as the “birth of the modern era of microbiome science, Stratum said.
 
This path of research eventually led to the first discoveries of what would later be known as postbiotics – beneficial but inanimate microbes or their components which, because they are heat-killed, have distinct manufacturing advantages over probiotics.
 
“Whether a postbiotic ends up being defined as the beneficial components of microbial fermentation, the heat-treated microbial cells themselves, or a combination of the two, they do have some distinct manufacturing and marketing advantages over probiotics. Since they are not live microbes, shelf stability and survival through the gut can be much more predictable,” Nena Dockery, scientific and regulatory manager at Stratum Nutrition, said.