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A roundup of the ISAPP consensus definitions: probiotics, prebiotics, synbiotics, postbiotics and fermented foods

By Dr. Mary Ellen Sanders, PhD, ISAPP Executive Science Officer

ISAPP has long recognized the importance of precise definitions of the ‘biotic’ family of terms. As a scientific organization working to advance global knowledge about probiotics, prebiotics, synbiotics, postbiotics and fermented foods, we believe carrying out rigorous scientific studies—and comparing one result to another—is more difficult if we do not start with a clear definition of what we are studying.

Over the past 8 years, ISAPP has endeavored to bring clarity to these definitions for scientists and other stakeholders. ISAPP board members have met with other top experts representing multiple perspectives and specialties in the field to develop precise, useful and appropriate definitions of the terms probiotics, prebiotics, synbiotics, postbiotics and fermented foods. The definitions of these first four terms have all entailed the requirement that the substance be shown to confer a health benefit in the target host. Fermented foods have multitudes of sensorial, nutritional and technological benefits, which drive their utility. A health benefit is not required.

The problem with health benefits

The definitions provide significant advantages for the scientific community in terms of clarity but complexity arises when the same definitions are accepted by regulatory agencies. This requirement for a health benefit as part of the probiotic definition has been rigorously implemented in the European Union. Currently, with the exception of a few member states, the term probiotic is prohibited. The logic is that since a health benefit is inherent to the term probiotic and since there are no approved health claims for probiotics in the EU*, the term ‘probiotic’ is seen to be acting as a proxy for a health claim. This has frustrated probiotic product companies who believe they have met the scientific criteria for probiotics, yet cannot identify their product as a probiotic in the marketplace because they have not received endorsement of their claims by the EU. This is not an issue resulting from an unclear definition, since probiotics surely should provide a health benefit, but rather from a lack of agreement as to what level of evidence is sufficient to substantiate a health benefit.

ISAPP remains committed to the importance of requiring a health benefit for the ‘biotic’ family of terms (outlined in the table below). It’s clear that all of these definitions are meaningless unless the requirement that they confer a health benefit is considered as essential by all stakeholders. One could reasonably discuss whether the required levels of evidence for foods and supplements are too high in some regulatory jurisdictions, but the value of these substances collapses in the absence of a health benefit.

Summary of ISAPP consensus definitions

With the publication of the most recent ISAPP consensus paper, this one on postbiotics, I offer a summary below of the five consensus definitions published by ISAPP. Each definition is part of a comprehensive paper resulting from focused discussions among experts in the field and published in Nature Reviews Gastroenterology and Hepatology (NRGH). These papers are among the top most viewed of all time on the NRGH website and are increasingly cited by scientists and regulators.

Table. Summary of ISAPP Consensus Definitions of the ‘Biotics’ Family of Substances. Probiotics, prebiotics, synbiotics and postbiotics have in common the requirement for a health benefit. They may apply to any target host, any regulatory category and must be safe for their intended use. Fermented foods fall only under the foods category and no health benefit is required.

Definition Key features of the definition Reference
Probiotics Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host Grammatical correction of the 2001 FAO/WHO definition.

No mechanism is stipulated by the definition.

 

Hill et al. 2014
Prebiotics A substrate that is selectively utilized by host microorganisms conferring a health benefit Prebiotics are distinct from fiber. Beneficial impact on resident microbiota and demonstration of health benefit required in same study. Gibson et al. 2017
Synbiotics A mixture comprising live microorganisms and substrate(s) selectively utilized by host microorganisms that confers a health benefit on the host Two types of synbiotics defined: complementary and synergistic. Complementary synbiotics comprise probiotic(s) plus prebiotic(s), meeting requirements for criteria for each. Synergistic synbiotics comprise substrate(s) selectively utilized by co-administered live microbe(s), but independently, the components do not have to meet criteria for prebiotic or probiotic. Swanson et al. 2020
Postbiotics Preparation of inanimate microorganisms and/or their components that confers a health benefit on the host Postbiotics are prepared from live microbes that undergo inactivation and the cells or cellular structures must be retained. Filtrates or isolated components from the growth of live microbes are not postbiotics. A probiotic that is killed is not automatically a postbiotic; the preparation must be shown to confer a health benefit, as well as meet all other criteria for a postbiotic. Salminen et al. 2021
Fermented Foods Foods made through desired microbial growth and enzymatic conversions of food components Fermented foods are not the same as probiotics. They are not required to have live microbes characterized to the strain level nor have evidence of a health benefit. Types of fermented foods are many and are specific to geographic regions. Compared to the raw foods they are made from, they may have improved taste, digestibility, safety, and nutritional value. Marco et al. 2021

 

 

*Actually, there is one approved health claim in the EU for a probiotic: Scientific Opinion on the substantiation of health claims related to live yoghurt cultures and improved lactose digestion (ID 1143, 2976) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

 

Further reading: Defining emerging ‘biotics’

New publication addresses the question: Which bacteria truly qualify as probiotics?

Although the international scientific consensus definition of probiotics, published in 2014, is well known—”live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”—the word is often used incorrectly in practice.

A recent article published in Frontiers in Microbiology builds on this definition and describes four criteria for accurate use of the word ‘probiotic’. Eight scientists co-authored the paper, including two ISAPP board members. The project was initiated by industry scientists affiliated with IPA Europe.

The authors explain why it’s important for scientists and companies to be sure the four identified criteria apply before using the term ‘probiotic’. Given the many misuses of the term that are evident today, however, consumers need to scrutinize ‘probiotic’ products to be sure they are legitimate.

Read the ISAPP press release on this publication here.

See an infographic summary of this publication here.

 

 

The FDA’s view on the term probiotics, part 1

By James Heimbach, Ph.D., F.A.C.N., JHEIMBACH LLC, Port Royal, VA

James Heimbach, food and nutrition regulatory consultant

Over the past 20 years as a food and nutrition regulatory consultant, I have filed about 40 GRAS notices with the United States Food and Drug Administration (FDA), including 15 strains of probiotic bacteria and 5 prebiotics. This fall I submitted notices dealing with 4 strains of bacteria and on January 16 received a telephone call from FDA that surprised me and initially infuriated me, but which I have come to understand.

The essence of the call was that FDA was declining to file my probiotic notices because the notices had identified the subject bacteria as “probiotics” or “probiotic bacteria.” FDA suggested that I resubmit without calling the subject microorganisms “probiotics.”

 

 

As I said, I was surprised and frustrated, and I still would prefer that when FDA makes a policy swerve they would do it in a way that does not make extra work for me and delay my clients’ ability to get to market in a timely manner.

What I have had to do here is remove my advocate’s hat and put on my regulator’s hat. (I worked for FDA for a decade . . . long ago [1978 to 1988], but I still remember how to think like a regulator.) And here is the issue. Recall that GRAS is concerned with safety, not efficacy (generally recognized as safe, or GRAS), and the information provided in a GRAS notice is focused on safety (although benefits may be more-or-less incidentally covered). The reviewers at FDA are charged with assessing whether the notice provides an adequate basis to conclude that there is a reasonable certainty that no harm will result from the intended use. They are not charged, and they are not equipped, to evaluate what benefits ingestion of the substance or microorganism might provide. So they are not in a position to say whether the subject microorganism will “confer a health benefit on the host,” which is to say, they are not in a position to say whether or not it may be regarded as a probiotic. Remember, probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (Hill et al. 2014).

Given that the FDA reviewers cannot say whether the notified microorganism is rightly called a probiotic, they are reluctant to sign off that they have no questions about a notice that calls it one. Regulatory agencies have to be careful; things sometimes come back to haunt them. Those who have been following FDA’s GRAS-notice response letters for a couple of decades will be aware that the agency is putting more and more disclaimers into the letters—about standards of identity, about potential labeling issues, about benefits shown in clinical trials, and about Section 201(II) of the FD&C Act.

One concern that FDA likely has is that if some issue comes up in the future regarding a claim made for benefits from use of a product containing the subject bacterium, someone may make the argument that FDA had accepted that the strain is indeed a probiotic and so it presumably confers probiotic benefits. In the case of probiotics, there are also some internal FDA politics. As ISAPP meeting attendees may already be aware, FDA’s Center for Biologics Evaluation and Research (CBER) would like to claim jurisdiction over all administration of live microorganisms, and the Center for Food Safety and Applied Nutrition (CFSAN) does not seem willing to have a confrontation.

I suspect that a similar situation obtains with the term “prebiotic.” Although I have filed a number of GRAS notices for prebiotics, they haven’t been called that; they have been called fructooligosaccharides, or tamarind seed polysaccharide, or polydextrose, or 2’-O-fucosyllactose. I don’t know how FDA would respond if a GRAS determination were filed with the substance labeled as a prebiotic.

So, I’ve decided that my sympathies lie with FDA. Until and unless a microorganism has been confirmed by competent authority to have probiotic properties when used as intended in a GRAS notice, FDA is probably correct in rejecting its right to be labeled a probiotic. If it’s any consolation, this new position by the FDA has its origin in their acknowledgment of the official scientific definition of the word “probiotic”.

When Mary Ellen Sanders (ISAPP’s Executive Science Officer) reviewed my first draft of this note, she asked what I had in mind by “competent authority,” to which I don’t have a good answer at the present time except to insist that it is not FDA’s Division of GRAS Notice Review. Thirty years ago, when I was at FDA, I was in the Office of Food Science and Nutrition, and that office was charged with making determinations of that type (although I don’t recall anything about probiotics coming before us). But FDA no longer has such an office. Until it does, or until it agrees on another source of authority on designation of microorganisms as non-CBER-domain probiotics, I suspect that CFSAN will continue to be very cautious in this area.

Read part 2 of this blog series here.