Current status of research on probiotic and prebiotic mechanisms of action

By Mary Ellen Sanders, PhD, ISAPP Executive Science Officer

Human intervention studies in the fields of probiotics and prebiotics assess the health effects of these ingredients, whether it’s improving specific symptoms or preventing the occurrence of a health condition. Yet scientists in the field recognize the importance of learning the ‘chain of events’ by which probiotics and prebiotics are able to confer health benefits. Such mechanistic insights allow better probiotic selection and development of therapeutic approaches, as well as more precise dosing.

Mechanisms of action for probiotics and prebiotics are complex and often difficult to pinpoint, especially since any given health benefit may derive from multiple co-functioning mechanisms. However, scientists have made incremental gains in understanding these mechanisms. This scientific progress was covered in a recent webinar co-presented by ISAPP and ILSI-Europe, titled Understanding Prebiotic and Probiotic Mechanisms that Drive Health Benefits. Speakers for the webinar were:

  • Sarah Lebeer, University of Antwerp, Belgium
  • Colin Hill, University College Cork, Ireland
  • Karen Scott, University of Aberdeen, UK
  • Koen Venema, Maastricht University – campus Venlo, The Netherlands

The webinar was held live on September 17, 2020. Of the 499 webinar registrants, 357 attended the webinar live from 57 countries, from Australia to the US. ISAPP and ILSI-Europe hope the webinar will serve as a resource for people who want a rapid overview about mechanisms of action.

Watch the full webinar here, and read further for a summary of key points from these experts.

Prebiotic benefits and mechanisms of action

Prebiotics are defined as substrates that are “selectively utilized by host microorganisms conferring a health benefit”. ‘Utilization’ in the gut may involve crossfeeding, which means products produced by the first microbes degrading the prebiotic can then be used by different members of the host microbiota – so it may take a series of complex steps to get to a final health outcome. However, selective utilization and health benefit are always required for a substance to meet the definition of a prebiotic.

The health benefit of a prebiotic can be local (in the gut) or systemic. Locally, prebiotics can act via fecal bulking, as they are typically types of fiber. In addition, they can produce short-chain fatty acids (SCFAs), which reduce gut pH and thereby can discourage pathogenic and toxigenic activity of gut microbes, increase calcium ion absorption and provide energy for gut epithelial cells.

Systemic functions of prebiotic metabolism include them being used as substrates for microbes that produce or interact with host cells to produce molecules with neurochemical, metabolic or immune activity. Further, SCFAs can end up in the blood and can reach the liver, muscles and the brain. The SCFAs interact with specific host receptors and can lead to the release of satiety hormones or interact with receptors in the liver, adipose tissue and muscle tissue, leading to reduced inflammation. Prebiotics can also interact directly with immune cells.

Probiotic health effects and mechanisms of action

Health and disease are the end results of complex interactions on a molecular scale within a human or animal host.  Host molecules also interact with microbial molecules, including those molecules introduced with or produced by probiotics. Designing studies to discover probiotic mechanisms in human research is extremely challenging because both host and probiotic are very complex systems that most probably engage with one another on multiple levels. Probiotic molecules can have direct effects and downstream effects, and we are aware of only a few cases where a health effect can be tied to one specific probiotic molecule.

Probiotics can interact directly with the host, but also can act indirectly by influencing the microbiome. There may be many different mechanisms by which a given probiotic interacts with the host.

It is interesting to note that probiotics use some of the same types of mechanisms (pili, small molecule production, etc.) that are used by pathogens, microbes that have a detrimental effect on the host.  But these shared mechanisms are usually connected to surviving or colonising strategies, not those that cause damage to the host.

L. rhamnosus GG is a well-researched model probiotic, for which many mechanisms have been identified, including pili, immune modulators and lactic acid production, some mechanisms shared with other probiotic strains and species. Other studies have identified mechanisms for novel types of probiotics. For example, in mice and humans taking a strain of Akkermansia, heat killed cells had the same or even better effect on markers of metabolic health, which implies that the molecules (perhaps proteins in the bacteria, unaffected by heat treatment) are mediating the effect in this case.

See here to watch the webinar in full.



EFSA’s QPS committee issues latest updates

By Bruno Pot, PhD, Vrije Universiteit Brussel and Mary Ellen Sanders, PhD, Executive Science Officer, ISAPP

On July 2nd, the European Food Safety Authority (EFSA) published the 12th update of the qualified presumption of safety (QPS) list, a list of safe biological agents, recommended for intentional addition to food or feed, covering notifications from October 2019-March 2020. It was good news to all stakeholders to see that EFSA discussed the recent taxonomic changes within the genus Lactobacillus (see ISAPP blog here) as well as addressed some microbes being considered as potential, novel probiotics.

What is QPS?

In 2005 EFSA established a generic approach to the safety assessment of microorganisms used in food and feed, prepared by a working group of the former Scientific Committee on Animal Nutrition, the Scientific Committee on Food and the Scientific Committee on Plants of the European Commission. This group introduced the concept of “Qualified Presumption of Safety” (QPS), which described the general safety profile of selected microorganisms. The QPS process was mainly developed to provide a generic pre‐evaluation procedure harmonized across the EU to support safety risk assessments of biological agents performed by EFSA’s scientific panels and units. A QPS assessment is performed by EFSA following a market authorisation request of a regulated product requiring a safety assessment. Importantly, in the QPS concept, a safety assessment of a defined taxonomic unit is performed independently of the legal framework under which the application is made in the course of an authorisation process.

QPS status is granted to a taxonomic unit (most commonly a species), based on reasonable evidence. A microorganism must meet the following four criteria:

1.       Its taxonomic identity must be well defined.

2.       The available body of knowledge must be sufficient to establish its safety.

3.       The lack of pathogenic properties must be established and substantiated (safety).

4.       Its intended use must be clearly described.

Any safety issues, noted as ‘qualifications’, that are identified for a species assessed under QPS must be addressed at the strain or product level. Microorganisms that are not well defined, for which some safety concerns are identified or for which it is not possible to conclude whether they pose a safety concern to humans, animals or the environment, are not considered suitable for QPS status and must undergo a full safety assessment. One generic qualification for all QPS bacterial taxonomic units is the need to establish the absence of acquired genes conferring resistance to clinically relevant antimicrobials (EFSA, 2008).

If an assessment concludes that a species does not raise safety concerns, it is granted “QPS status”. Once EFSA grants a microorganism QPS status, it is included on the “QPS list” and no microorganism belonging to that group needs to undergo a full safety assessment in the European Union.

The QPS list is re‐evaluated every 6 months by the EFSA Panel on Biological Hazards based on three “Terms of Reference” (ToR)*. This evaluation is based on an extensive literature survey covering the four criteria mentioned above.

What happened to the genus Lactobacillus?

In April 2020, based on a polyphasic approach involving whole genome sequencing of more than 260 species of the former genus Lactobacillus, the genus was reclassified into 25 genera including the emended genus Lactobacillus, which includes host-adapted organisms that have been referred to as the L. delbrueckii group, the earlier described genus Paralactobacillus as well as 23 novel genera, named Acetilactobacillus, Agrilactobacillus, Amylolactobacillus, Apilactobacillus, Bombilactobacillus, Companilactobacillus, Dellaglioa, Fructilactobacillus, Furfurilactobacillus, Holzapfelia, Lacticaseibacillus, Lactiplantibacillus, Lapidilactobacillus, Latilactobacillus, Lentilactobacillus, Levilactobacillus, Ligilactobacillus, Limosilactobacillus, Liquorilactobacillus, Loigolactobacilus, Paucilactobacillus, Schleiferilactobacillus, and Secundilactobacillus. Read more in the original paper here or on the ISAPP blog here).

These name changes could have considerable economic, scientific and regulatory consequences, as discussed during an expert workshop organised by the Lactic Acid Bacteria Industrial Platform (LABIP). One of the points discussed during this workshop was the possible implication of the name change on the QPS list in Europe and the FDA’s GRAS list in the USA.

What did EFSA do?

In a 42-page document, which can be found here, amongst others, the species of the former genus Lactobacillus that were already listed on the QPS list, have been formally renamed at the genus level. The species names remained the same, as the taxonomic revision from April 2020 only affected the genus name. As a result, the genus names of 37 former Lactobacillus species on the QPS were updated, and now span 13 different genera. Table 1 delineates these nomenclature updates.

Table 1: Taxonomic revision of the 37 species formerly of the Lactobacillus genus present on the QPS list (published here).

Earlier denomination                                                      Updated denomination
Lactobacillus acidophilus                     Lactobacillus acidophilus
Lactobacillus alimentarius Companilactobacillus alimentarius
Lactobacillus amylolyticus Lactobacillus amylolyticus
Lactobacillus amylovorus Lactobacillus amylovorous
Lactobacillus animalis Ligilactobacillus animalis
Lactobacillus aviarius Ligilactobacillus aviarius
Lactobacillus brevis Levilactobacillus brevis
Lactobacillus buchneri Lentilactobacillus buchneri
Lactobacillus casei Lacticaseibacillus casei
Lactobacillus collinoides Secundilactobacillus collinoides
Lactobacillus coryniformis Loigolactobacillus coryniformis
Lactobacillus crispatus Lactobacillus crispatus
Lactobacillus curvatus Latilactobacillus curvatus
Lactobacillus delbrueckii Lactobacillus delbrueckii
Lactobacillus dextrinicus Lapidilactobacillus dextrinicus
Lactobacillus diolivorans Lentilactobacillus dioliovorans
Lactobacillus farciminis Companilactobacillus farciminis
Lactobacillus fermentum Limosilactobacillus fermentum
Lactobacillus gallinarum Lactobacillus gallinarum
Lactobacillus gasseri Lactobacillus gasseri
Lactobacillus helveticus Lactobacillus helveticus
Lactobacillus hilgardii Lentilactobacillus hilgardii
Lactobacillus johnsonii Lactobacillus johnsonii
Lactobacillus kefiranofaciens Lactobacillus kefiranofaciens
Lactobacillus kefiri Lentilactobacillus kefiri
Lactobacillus mucosae Limosilactobacillus mucosae
Lactobacillus panis Limosilactobacillus panis
Lactobacillus paracasei Lacticaseibacillus paracasei
Lactobacillus paraplantarum Lactiplantibacillus paraplantarum
Lactobacillus pentosus Lactiplantibacillus pentosus
Lactobacillus plantarum Lactiplantibacillus plantarum
Lactobacillus pontis Limosilactobacillus pontis
Lactobacillus reuteri Limosilactobacillus reuteri
Lactobacillus rhamnosus Lacticaseibacillus rhamnosus
Lactobacillus sakei Latilactobacillus sakei
Lactobacillus salivarius Ligilactobacillus salivarius
Lactobacillus sanfranciscensis Fructilactobacillus sanfranciscensis

EFSA further specifies that “To maintain continuity within the QPS list, all the strains belonging to a previous designed Lactobacillus species will be transferred to the new species. Both the previous and new names will be retained”. (Emphasis added.)

Impact of the QPS update on the probiotic field

The probiotic field can also take note of this current update for its review of two ‘next generation’ probiotic species evaluated for possible QPS status, Akkermansia muciniphila and Clostridium butyricumAkkermansia muciniphila has been actively researched as a probiotic to help manage metabolic syndrome (Depommier et al. 2019). A probiotic preparation containing both Akkermansia muciniphila and Clostridium butyricum has been studied in a randomized controlled trial for postprandial glucose control in subjects with type 2 diabetes (Perraudeau et al 2020). The committee’s decisions:

  • Akkermansia muciniphila is not recommended for QPS status due to safety concerns;
  • Clostridium butyricum is not recommended for QPS status because some strains contain pathogenicity factors; this species is excluded for further QPS evaluation.

The publication of the next scientific opinion updating the QPS list is planned for December 2020, based on the 6-month assessments carried out by the BIOHAZ Panel.


Due to its scientific rigor and continuous updates, the EFSA QPS efforts provide useful perspective for the global scientific community on safety of candidate microbes for use in foods. Their embrace of the new taxonomic status of lactobacilli signals to other stakeholders that it is time to start the process of doing the same. Further, their assessment of species being proposed and studies as ‘next generation’ probiotics is an important reminder that a microbe’s status as a human commensal is not a guarantee of its safety for use in foods.


*QPS Terms of Reference (ToR) (quoted from here):

ToR 1: Keep updated the list of biological agents being notified in the context of a technical dossier to EFSA Units such as Feed, Pesticides, Food Ingredients and Packaging (FIP) and Nutrition, for intentional use directly or as sources of food and feed additives, food enzymes and plant protection products for safety assessment.

ToR 2: Review taxonomic units previously recommended for the QPS list and their qualifications when new information has become available. The latter is based on a review of the updated literature aiming at verifying if any new safety concern has arisen that could require the removal of the taxonomic unit from the list, and to verify if the qualifications still efficiently exclude safety concerns.

ToR 3: (Re)assess the suitability of new taxonomic units notified to EFSA for their inclusion in the QPS list. These microbiological agents are notified to EFSA and requested by the Feed Unit, the FIP Unit, the Nutrition Unit or by the Pesticides Unit.


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.



ISAPP’s popular educational videos now feature subtitles in multiple languages

ISAPP’s series of six English-language videos are a useful resource for helping consumers answer important questions about probiotics, prebiotics, and fermented foods. In order to make these popular educational videos accessible to a wider global audience, ISAPP has now updated them with subtitles in multiple languages: Dutch, French, German, Indonesian, Italian, Japanese, Russian, and Spanish.

Dr. Roberta Grimaldi, a principal clinical research scientist who served as ISAPP’s Industry Advisory Committee representative from 2017-2019, led the video subtitling efforts.

“The videos are a good way to communicate information about these products, which are still not fully understood by consumers,” says Grimaldi. She says that while consumers see “a lot of miscommunication and misleading information” online, the easy-to-understand ISAPP videos help bring the scientific perspective to a broad audience.

Multi-lingual members of the ISAPP community stepped up to help with the translations, with Grimaldi managing the task and co-ordinating with the video production agency. She says, “It was definitely an amazing team effort, which I think gave us really great results.”

Science Translation Committee head Dr. Chris Cifelli underlines how worthwhile the video subtitles project has been for ISAPP. “Since ISAPP is an international organization, we have been working hard to make our educational materials accessible to as many people as possible. The subtitles allow the information in these videos to be shared much more widely, ultimately helping consumers make more informed decisions about probiotics, prebiotics, and fermented foods.”

Many of ISAPP’s infographics are also available in multiple languages.


How to change the language subtitles on an ISAPP video:

Step 1 – On the ISAPP videos page, click on the video.

Step 2 – Press pause and click the gear-like ‘Settings’ icon, to the right of the ‘CC’ icon.

Step 3 – Click on ‘Subtitles’ and select the language subtitle you prefer.

Step 4 – Resume the video by pressing play.

What makes a synbiotic? ISAPP provides a sneak peek at the forthcoming international scientific consensus definition

By Kristina Campbell, science and medical writer

The word ‘synbiotic’ is found on the labels of many different products, from supplements to chocolate bars, and it has generally been understood to be a combination of a probiotic and a prebiotic. But what happens when scientists want to test whether these combination products really deliver any health benefits? Can these products be tailored to have specific effects on the body or on the human gut microbiota? Agreeing on a clear definition of synbiotics is needed to provide focus for scientific research in this area, to facilitate the design of studies, and to allow for progress wherein their health effects are uncovered.

The scientific definition of synbiotic was the central topic of the international scientific panel brought together by ISAPP in May 2019 in Antwerp, Belgium. Members of the panel, eleven of the top academic experts in the field of probiotics and prebiotics, gathered to clarify a scientifically valid approach for use of the word ‘synbiotic’, and to communicate this by position paper. The outcome of this consensus panel is currently in press at Nature Reviews Gastroenterology & Hepatology.

Kelly Swanson, Professor in the Department of Animal Sciences and Division of Nutritional Sciences at University of Illinois at Urbana-Champaign, chaired the panel and led the paper’s publication. Swanson has been studying gastrointestinal health in both humans, companion animals (dogs and cats) and rodent models for the past 20 years—and having followed the rapid advances in the field of probiotics and prebiotics during those two decades, he knew the task of creating a synbiotic definition would not be easy.

He says, “The field is highly complicated, so an interdisciplinary panel was essential. The main areas of expertise included microbiology and microbial ecology; gastrointestinal physiology; immunology; food science; nutritional biochemistry and host metabolism.”

A timely discussion

According to Swanson, an increase in research interest, built on a foundation of recent scientific and technical gains, made this the right time to come to consensus on a synbiotic definition. He says, “Over the past decade, technological advances have allowed scientists to study the gut microbiome at a molecular level. In addition to characterizing the composition of the gut microbes, researchers are learning more about their biological activity and how they may impact host health.”

Furthermore, clarity about the definition was urgently needed because of the rapidly growing synbiotics market. Consumers seem to be more aware of synbiotics than ever, but they face a bewildering array of product offerings labeled as ‘synbiotic’ without a clear understanding of what that term entails and with no framework for establishing scientific efficacy. Swanson says, “As the field has moved forward and the sales of probiotics and prebiotics have increased, there has been more interest in combining substances to enhance efficacy. Some of these combinations may function as synbiotics, but it is not guaranteed. Rather than randomly combining substances together, there should be scientific rationale supporting their use.”

Clarifying the concept

One of the first questions the panel members had to tackle was whether to stick to the idea of a synbiotic as ‘probiotic plus prebiotic’, thus leaning heavily on the ISAPP-led international consensus definitions of probiotics and prebiotics published in 2014 and 2017, respectively. But the panel members decided this narrow scope would ultimately limit innovation in the synbiotic category.

Swanson explains, “While many synbiotics may be composed of an established prebiotic and established probiotic, the panel did not want to restrict scientific advances in the synbiotic category by requiring use of components already established on their own.”

As a result, he says, previously untested live microbes and potential prebiotic substances could be considered a synbiotic if the combination showed efficacy, and if the health benefit came from administering both the live microbe and the substrate it utilized—that is, the microbe together with its ‘food’.

Another conclusion from the panel is that probiotics (with known health benefits) and prebiotics (with known health benefits) cannot be called synbiotics unless they have been tested together. “There should be a rationale supporting the combination used, and then testing of the combination to confirm its efficacy,” says Swanson.

The panel suggests a synbiotic may be composed of either of the following, as long as efficacy is demonstrated for the combination:

  • Established probiotic + established prebiotic (each component meeting the efficacy and mechanistic criteria for each)
  • Previously untested live microbe + a substrate that is selectively utilized by the co-administered live microbe

Further details, including two different ‘categories’ of synbiotics, will be provided in the published paper.

In addition to the definition, the publication will cover the history of synbiotic-type products, how these products can be characterized, levels of evidence that currently exist versus levels of evidence desired, points about safety documentation and reporting, and relevant characteristics of the target hosts.

A remaining challenge—not just for the expert group, but also across the field—is the difficulty of establishing causal links between substances’ effects on the gut microbiota (e.g. ‘selective utilization’ of a substrate) and health outcomes.

While the publication of the synbiotic definition will be an important milestone, Swanson anticipates further discussion in the years ahead. “As more is learned, I expect the criteria for assessing synbiotic efficacy will continue to change,” he says.

An update on the scientific consensus definition of synbiotic was presented to ISAPP members at the 2020 virtual meeting in June.


The science on gut microbiota and intestinal gas: Everything you wanted to know but didn’t want to ask

By Kristina Campbell, science and medical writer

Even on the days when you don’t eat a large meal of Boston baked beans, the inside of your intestines is a gas-generating factory. This serves a valuable purpose for the body when everything is working as it should, with gases being produced and eliminated through a complex set of physiological processes. But sometimes gas becomes a problem—and this is when it’s valuable to know not only what contributes to intestinal gas symptoms, but also how dietary adjustments can alleviate some of the problems.

Dr. Fernando Azpiroz, Chief of Gastrointestinal Research at the Vall d’Hebron Research Institute and Professor of Medicine, Autonomous University of Barcelona (Spain), is an expert in both the pathophysiology of the gas produced in the digestive tract and the clinical problems related to intestinal gas. Dr. Azpiroz is the author of a chapter on intestinal gas in the well-known textbook, Sleisenger and Fordtran’s Gastrointestinal and Liver Disease, which is now in its 10th edition. And for more than 20 years he has been conducting research on digestive tract function, intestinal gas, and the contributions of the gut microbiota.

ISAPP caught up with Dr. Azpiroz to ask him about everything you wanted to know—where intestinal gas comes from, when it becomes a problem, and the latest research on the dietary changes that can reduce symptoms of intestinal gas while keeping the gut microbiota intact.

In different parts of the digestive tract, where does intestinal gas come from?

For the most part, the gas in the digestive system comes from metabolic activities of the colonic microbiota.

In addition, some air enters the stomach during swallowing. Most of this air is eliminated by eructation (i.e. burping), so there is a homeostasis. There is a small air chamber in the stomach of about 20 mLs, and this is pure atmospheric air, or CO2 after recent consumption of carbonated drinks.

In the small intestine, the neutralization of acids and alkali can theoretically produce large amounts of CO2. However, it’s more in theory than measured in experimental conditions.

Other gases originate from the metabolism of the gut microbiota. The residues of the diet that are not absorbed in the small bowel pass into the colon. These are the parts of the diets that we, as humans, cannot use. These pass into the colon, and in the colon serve as substrates for colonic microbiota. Gas is produced during this process of colonic fermentation.

What types of gases are produced in the digestive tract?

The composition of intestinal gas depends on where in the gut it is produced.

In the stomach, the gas is virtually all atmospheric air or CO2.

In the small bowel, theoretically it should be CO2, although the hard data are very scarce.

And in the colon, the largest component is likely hydrogen and CO2. But the data on that are very limited, and it is not known for sure that these theories are really true. The measurements of gas composition, in the colon or even in the gas eliminated per anus are still uncertain but so far the main concept is that most of the gas is hydrogen and CO2, and methane in subjects that have a methanogenic microbiota.

How does this gas normally get eliminated?

Throughout the GI tract, particularly the colon, about 80% of the gases produced are absorbed through the mucosa, pass into the blood, and are eliminated by breath. So only about 20-25% of the volume of gases produced, particularly in the colon, are eliminated per anus.

What influences the amount of gas produced?

The amount of gas produced in different subjects depends on two factors: one is the diet—the amount of residues (i.e. fiber) in the diet—and the second is the type of microbiota, which is very individual. It varies a lot from one subject to another.

How much intestinal gas is ‘too much’?

From the point of view of patients, of symptoms, what might be relevant is the volume of gases produced, and possibly the type of gases. One evolving idea is that some gases, which are produced in very small quantities, might serve as neurotransmitters, might play a role, but so far the information we have about the role of these gases is very limited so we cannot extrapolate that to clinical use.

Very recent data indicate that symptoms occur when the GI tract has a poor tolerance to its contents, and particularly to gas.

So what is the factor that makes gas produce symptoms? Well there are two factors. One is the amount of gas, and the other one is the tolerance of the subject.

In healthy subjects, it will typically take a large amount of gas to develop symptoms, if at all.

But even small amounts of gas in patients that have a hypersensitivity of the gut and poor tolerance to contents might contribute to their symptoms. This can be seen because, if we reduce the amount of flatulogenic substances in their diet, the symptoms reduce.

This is if we just take into consideration the volume of gas produced, but there is also another factor.

If we give a high flatulogenic diet or a high-residue diet, we know, because we have measured, that we increase the volume of gas produced into the colon. However, we also increase the amount of the fecal content in the colon. So it could be that these diets produce symptoms because they increase the amount of gas, but also because other non-gaseous components, the fecal content of the colon, also are poorly tolerated.

How can someone manipulate their diet to change the amount of intestinal gas that’s produced?

A ‘challenge’ diet, or a high flatulogenic diet in healthy subjects, makes them sick. They go from being symptom-free to having some symptoms, particularly flatulence and bloating.

In patients, the effect of the diet is more accentuated. If patients consume a diet with high residues they get very symptomatic, and if these patients will reduce residues in the diet, they see quite an improvement.

What are the options for dietary change when someone has IBS or wants to reduce gas symptoms?

One thing that has been shown recently is that the effect of a low-residue diet is similar regardless of the type of diet. In the past ten years or so there’s been a major trend with the use of low-FODMAP fermentable oligo-, di-, mono-saccharides and polyols diets.

However, the effect of these complex diets is not better than the effect of any sensible and simple low-residue diet. So if you reduce legumes, veggies from the diet, and fruits, you get a similar improvement.

The problem with low-residue diets, in particular the low-FODMAP diet, is that they introduce a restriction of the substrates for the feeding of the microbiota, and this is deleterious to the microbiota. The microbiota is impoverished.

The other limitation of low-residue diet is that the moment that the patient returns to a normal diet, the symptoms come back.

There is an alternative that has been shown in the past few years, which is to use some type of prebiotics that initially—because they are fermented—produce symptoms, but after a few days they induce an adaptation of the microbiota towards a microbiota that produces less gas with normal fermentation. And down the road, these prebiotics have a positive effect on symptoms in patients. As a matter of fact, the effect on symptoms is similar to a restrictive diet. The advantage of the prebiotics is that, after interruption, …the effect is sustained at least over a few weeks. And this is because it has been shown that prebiotics serve as substrates for microbiota and induce a proliferation of beneficial organisms.

There is also some preliminary evidence that some probiotics reduce the volume of gas production and reduce digestive symptoms in patients.

Is it a good idea to test your gut microbiota when you have IBS or gas symptoms?

There are different companies that claim that by analyzing microbiota they can diagnose some functional conditions, for instance IBS. The practical application of this technology has not been demonstrated. Usually they are expensive techniques and of no value.

It’s important to understand the real value of these methodologies and take the myth out of ‘wonder’ techniques that make a diagnosis from the microbiota and claim it explains everything.

Hopefully, this might be true in the future, but not right now. And actually many of the technologies that are used for this type of analysis are suboptimal.

 A previous blog post by Dr. Bob Hutkins on diet, gut microbiota, and intestinal gas is ISAPP’s most-read blog post of all time. Read it 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.

Defining emerging ‘biotics’

By Mary Ellen Sanders PhD

From its inception, ISAPP has been committed to clarity in both the definitions and the contextual use of terms in the fields of probiotics and prebiotics fields. This is reflected in the FAO/WHO probiotic guidelines working group conducted immediately prior to the first ISAPP meeting in 2002, as well as our more recent consensus panels convened on probiotics (2013), and prebiotics (2016). We also have additional panels in progress on synbiotics (convened in May 2019 in Antwerp), fermented foods (scheduled for September) and postbiotics (scheduled for December).

A recently published paper, Emerging Health Concepts in the Probiotics Field: Streamlining the Definitions, addresses definitions of many newer terms in the ‘biotics’ arena, including probiotics, prebiotics, synbiotic, pharmabiotics, postbiotics, probioceuticals, paraprobiotics, oncobiotics, psychobiotics, and live biotherapeutic products. In my opinion, although this paper provides useful discussion of issues surrounding the proliferation of terms in the ‘biotics’ area, it falls short of providing clear direction for the field and indeed may well add to confusion by introducing unnecessary, new and poorly defined terms.

For example, the term ‘symbiotics’ is perpetuated, presumably as a synonym to synbiotic. It was a missed opportunity to clarify that the term ‘synbiotic’ is derived from the Greek root ‘syn’ meaning ‘with’ or ‘together.’ The term ‘symbiotic’ is simply incorrect, adds nothing and should be eliminated altogether.

This paper fails to advance the ISAPP consensus definition of prebiotic, published in 2017, by lead author Glenn Gibson, co-inventor of the terms ‘prebiotic’ and ‘synbiotic’. It is not clear whether the authors disagree with the ISAPP consensus definition, and if so, on what basis. They state that the ISAPP consensus definition is “the most actual definition”, the meaning of which is not clear to me, but then use an outdated definition in their summary box.

Further is the failure to acknowledge the broad scope of the definition of probiotics. Live biotherapeutic products (LBPs), which the paper states is a term that was “recently” introduced by the FDA, has been in use for over at least 15 years by the FDA’s Center for Biologics Evaluation and Research. The authors equate LBPs (which are defined as drugs) with next generation probiotics, yet these do not have to fall under the drug category any more than traditional probiotics are necessarily foods. Next generation probiotics, traditional probiotics or just probiotics can fall under numerous regulatory categories including foods, infant formulas, drugs, supplements, animal feeds, medical foods, foods for special dietary uses, and perhaps even cosmetics or medical devices. Thus, regulatory category is not stipulated by the definition, which is appropriate.

One of the difficulties with sorting through these terms is the lack of any consistent basis for defining them. Some terms, such as pharmabiotics and LBPs, are linked to specific regulatory categories. Others are defined by the nature of how they are comprised: live cells, cell components, or fermentation endproducts. Others are defined by their physiological benefit: psychobiotic, oncobiotic, immunobiotic. Even still, others are defined by their state of innovation: traditional vs. next generation probiotics. This state of affairs makes is impossible to develop a logical framework for categorizing them. Instead, we are left with a long list of substances that might be related, but have little real value. Where does it all stop? Next we will have to sift through thera/metabo/gen/retro/plas/func-biotics or any other pointless terms that can be arbitrarily slapped in front of ‘biotic.’

Certainly, there is nothing to prevent any person from coining a new term for a niche development. The many stakeholders in the broader ‘biotics’ field will, I suppose, determine any given term’s utility. I believe it would have been worthwhile for this paper to make an appeal to scientists to refrain from muddying the water by proposing new terms, and instead use existing terms with appropriate modifiers. For example, use ‘immune-active probiotic’ instead of ‘immunobiotic’, or ‘probiotic drug’ instead of ‘live biotherapeutic product.’ This approach is clearer to regulators and international organizations such as Codex Alimentarius, the US Food and Drug Administration and European Food Safety Authority. To the extent that the definitions of terms need to be clarified, I believe that the ISAPP approach, using groups of 10 or more well-known academic experts in the field reaching a consensus after extensive background search, is preferred over unilateral proclamations as delivered by this paper.

The Art of Interpretation

By Prof. Gregor Reid, BSc Hons PhD MBA ARM CCM Dr HS, Lawson Research Institute, University of Western Ontario, Canada

It takes a certain degree of intelligence to become a scientist, and certainly hard work to be able to fund a lab and students. Yet, is it not bemusing when scientists cannot interpret simple things like definitions and the results of human studies?

I’ve written repeatedly, as have others, about the definition of probiotics (in case you forgot – “Live microorganisms that, (or which) when administered in adequate amounts, confer a health benefit on the host”),1,2 and yet people look at it and must think that ‘dead’ fits, as does ‘consume’, as does ‘colonize’. It beggar’s belief how such a simple definition can be so badly interpreted by intelligent people.

Time after time papers I review mis-write and/or misinterpret the definition. Conference after conference, I hear dieticians, pharmacists, physicians, scientists not only get the definition wrong, but say things like ‘the probiotics in kombucha’ when there are none, ‘we have lots of probiotics in our gut’ when you don’t unless you consumed them, ‘the lactobacilli need to colonize’ when this was never a prerequisite nor does it happen except in rare instances.

The interpretation gets more difficult when people use terms that are completely undefined like ‘psycho-biotics’ and ‘post-biotics’. Even ‘dead probiotics’ have been used in clinical trials – God help us when the authors can’t even define it. Why stop at killing probiotic strains? Why not just kill any bacterial strain? Even the gut-brain axis which is now mentioned everywhere in the literature is undefined and unproven. The vagus nerve links to many body sites as does the nervous system, making it exceedingly difficult to prove that brain responses are only due to the gut microbes.

Everyone can site a manuscript that has been badly analyzed, interpreted or peer-reviewed, or whose findings are overblown. But let’s not excuse this as ‘it’s just science’ or ‘it’s just the way it is.’ No, it is not. When a paper uses a product that is stated to be ‘probiotic’, there is an onus on the authors to make sure the product meets the appropriate criteria. These have been stated over and over again and reiterated this March, 2019.3

If scientists and science writers are really that smart, then how do they keep getting this wrong? How do we let a poorly analyzed paper get published and allow authors to say that Bacteroides fragilis is a probiotic that can treat autism?4,5 And when this leads to companies claiming probiotics can treat autism, why do other scientists convey cynicism for the field instead of against their colleagues and specific companies making the false claims?

Where does opinion cross the line with ignorance or stupidity? Martin Luther King Jr. must have predicted life today when he said, “Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity.”

Is it envy or anger that drives the anti-probiotic sentiments? It seems to go far beyond a difference of opinion. When the BBC and JAMA fail to comment on two much better and larger studies on the effects of probiotics published6,7 at the same time as the ones in Cell8,9 that were promoted by press releases, what is driving opinion? The science or the press releases? Are the journalists and communications’ people interpreting study results vigorously? One cannot believe they are.

In an era where anyone can write anything at any time and pass it along to the world, what are we recipients to do? Just go with our instincts? Soon, we will not know the difference between fact and fake news. The avatars will be so real, we will act on falsehoods without knowing. When all news is fake, where does that leave us as people, never mind scientists?

Manuscripts are sent for peer-review but how many reviewers are experts in bioinformatics, molecular genetics, clinical medicine, biostatistics and what happens on the front line of products to consumers or patients? Like it or not, poor studies will get out there and it will be the media who will tell the story and interpret the findings or press releases.

One must hope that confirmatory science will continue and if it fails, the writers and readers will stop citing the original incorrect report. But how often does that happen? And what are we left with?

It takes effort to object or fight back, but if we don’t then the fake news will become the norm.

Try interpreting that if you will.


Literature Cited

  1.  FAO/WHO. 2001. Probiotics in food.
  2. Hill C. et al. 2014. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotics. Nat. Reviews Gastroenterol. Hepatol. 11(8):506-14.
  3. Reid G. et al. 2019. Probiotics: reiterating what they are and what they are not. Front. Microbiol. 10: article 424.
  4. Hsiao et al. 2013. Microbiota modulate behavioral and physiological abnormalities associated with neurodevelopmental disorders. Cell. 155(7):1451-63.
  5. Sharon G, et al. 2016. The central nervous system and the gut microbiome. Cell. 167(4):915-932.
  6. Korpela K. et al. 2018. Probiotic supplementation restores normal microbiota composition and function in antibiotic-treated and in caesarean-born infants. Microbiome. 6(1):182.
  7. De Wolfe, T.J. et al. 2018. Oral probiotic combination of Lactobacillus and Bifidobacterium alters the gastrointestinal microbiota during antibiotic treatment for Clostridium difficile infection. PLoS One. 13(9):e0204253.
  8. Suez J. et al. (2018). Post-antibiotic gut mucosal microbiome reconstitution is impaired by probiotics and improved by autologous FMT. Cell. 2018 Sep 6;174(6):1406-1423.e16.
  9. Zmora N. et al. 2018. Personalized gut mucosal colonization resistance to empiric probiotics is associated with unique host and microbiome features. Cell. Sep 6;174(6):1388-1405.e21.
probiotics calendar

Probiotics in the Year 2018

Prof. Daniel Merenstein MD, Georgetown University School of Medicine

Messages about probiotics seem to be everywhere. It is difficult for me to keep up with the emails, links, and stories I am sent by friends and colleagues. I am regularly asked my opinion about new studies. Null trials seem to really generate the most interest, with some people looking for limitations of the study and others generally over-extrapolating the null results, seemingly at times to generate the brashest headlines.

Today I want to take a step back and share how I see probiotics in 2018.

I just reviewed a 109-page NIH grant focused on a probiotic intervention for use in a resource poor area. Throughout the grant, the authors never once defined probiotics—presumably because the definition is so commonly known. They did define ‘prebiotics’ but they never felt the need to define probiotics. Imagine that: 2018, and probiotics no longer need to be defined lest the authors seem pedantic. This would not have been the case even five years ago.

Probiotics are backed by real science, they are here to stay, and they are impacting both how we practice medicine and how consumers care for their own health. These are real products with some robust outcomes supported by well-done, independent studies. That is worth emphasizing: there is level 1 evidence for certain products and indications. On the other hand, the use of many probiotics is not evidence-based and expectations about some are not realistic. In the real world, products do not work for every indication or study population. Effect sizes and effectiveness for most indications are often small. One of my true hesitations about fecal microbial transplantation* is how nearly every study has over 90% effectiveness. That gives me cause for concern.

Thus, when there is a null trial the skeptics shouldn’t over extrapolate and the probiotic devotees should not attack the authors. We can look to studies on other treatments as an example: In November of this year NEJM published an article that showed a new antibiotic did not work well for gonorrheal pharyngeal infections. What I didn’t see were any headlines stating, “Antibiotics don’t work for pharyngeal infections.” But headlines involving probiotics often make erroneously broad generalizations. There clearly are indications for which no probiotic has been or will be shown to work. Selling a probiotic for that indication is clearly unethical. But considering the robust evidence base we have for the indication of probiotics for gastroenteritis, it is inappropriate – after 2 null trials – for headlines to read, “Probiotics Do Not Ease Stomach Flu” or “Probiotics No Better Than Placebo for Gastroenteritis”.

This fall I spoke about probiotics at two conferences, the annual meetings of the American Academy of Family Physicians (AAFP) and the annual meeting of the Academy of Nutrition and Dietetics  (FNCE). I had never spoken at either conference. With the help of a colleague, I gave two talks at AAFP; both were over-registered with all 600+ spots taken. At the FNCE, the talk was also over-registered with 350 in attendance. The level of interest in probiotics was astonishing.

What I learned from my talks is that as long as there are well-designed studies demonstrating benefits, professionals are open to probiotics and will use them correctly. Further, both the FNCE and AAFP audiences shared similar concerns: can you trust that probiotic product labels are truthful regarding contents, and are there any safety concerns? Good science and quality oversight need to continue to address these important concerns.

2018 was a great year for the advancement of probiotics in mainstream medicine. However, I think for physicians to fully embrace probiotics, the probiotic industry will better need to police itself and make sure the products they sell are what they say they are. Then they need to communicate this on the product label, using a valid quality seal (such as offered by USP), so physicians and consumers will be confident about what they are using. If the science continues to advance and we communicate about it responsibly, the use of probiotics will be used appropriately and more frequently – as they should be.


*For all my colleagues in the gastroenterology world who have fallen in love with fecal transplant for recurrent C. diff,  the totality of evidence as of this writing is:  187 total patients, 5 studies (2 enema, 2 colonoscopy and 1 via-nasoduodenal tube), and punchline, TWO studies were blinded. The one with the lowest rate of success was the only one that was placebo-controlled and blinded. The other blinded study was donor versus patients’ own stools. Stew on that and feel free to correct me.  

Minimum criteria for probiotics: ISAPP perspectives

By Mary Ellen Sanders PhD, Executive Science Officer, ISAPP

During its 2018 annual meeting (June 5-7), ISAPP convened a group of 30 participants from 13 countries to address issues associated with global harmonization of regulations for probiotics and prebiotics. This topic was of interest due to the broad international presence at this meeting, ISAPP’s first in Asia. The goal of this group was to provide regulators guidance derived from this assemblage of experts regarding the minimum criteria a probiotic food or supplement should meet. Drs. Seppo Salminen, Yuan-Kun Lee, and Gabriel Vinderola, who chaired this group, recently completed a summary titled “ISAPP position statement on minimum criteria for harmonizing global regulatory approaches for probiotics in foods and supplements”.

In December of 2017 the International Probiotic Association (IPA) presented a proposal to Codex Alimentarius – a recognized body that develops global standards and guidelines related to foods – regarding establishment of guidelines for probiotic foods. Codex Alimentarius accepted this proposal and requested that Argentina prepare draft guidelines to be considered in the 2018 session of the Codex Alimentarius  Committee on Nutrition and Foods for Special Dietary Use. ISAPP representatives and group coordinators (Sanders, Salminen and Vinderola) took part along with IPA in a scientific meeting in Argentina to present the ISAPP views to local authorities and experts.  IPA hopes that these efforts will lead to harmonized regulations since “this lack of harmonization in industry practice and legislation remains and often leads to serious issues and concerns for the probiotics industry, regulators, and even consumers in regard of quality, safety and labelling.” (Page1 of the proposal)

As the efforts of harmonization of regulations for probiotic foods through Codex progresses, ISAPP offers – through this summary document – its perspectives on minimum criteria for probiotics. The ISAPP group’s conclusions echo the principles outlined in the IPA proposal. Our hope is that this ISAPP document will provide useful perspective to local regulators. As of this writing, Prof. Salminen has delivered this document to the Codex representative at the Finnish Ministry of Agriculture and Food. We hope that further dissemination of the perspectives in this document will contribute to a science-based approach to global harmonization of regulations for probiotics.

See the document for the list of minimum criteria.

ISAPP Releases New Infographic – Probiotic Checklist: Making a Smart Selection

Not all products labelled “probiotic” are true probiotics. ISAPP just released a new infographic focused on helping consumers make smart selections when examining probiotic products. The infographic addresses identifying products backed by science, effective dosing, and more.

See and download the full infographic here.

See all ISAPP infographics here.



Guides for use of probiotics in the clinic – some recent ISAPP initiatives

By Mary Ellen Sanders, PhD

At the ISAPP meeting earlier this month, Prof. Dan Merenstein, MD, presented a summary of recent ISAPP initiatives focused on helping translate the evidence of probiotics and prebiotics into clinical action.

A 2013 paper reported that 87% of hospital formularies surveyed in the United States carried at least one probiotic. Yet when Merenstein looked at the names of the products tested, many were not supported by evidence for such uses. This highlights the need for clinicians to have access to clear, evidence-based probiotic use guidelines.

ISAPP has worked through a variety of avenues to get information into the hands of clinicians. It has supported continuing education credit activities, webinars, collaboration with clinical organizations to develop guidelines, publications in clinical journals, presentations at clinical meetings, and simplified summaries using infographics and videos. Some examples include the following.


World Gastroenterology Organisation Global Guidelines – Probiotics and Prebiotics

This document is the most visited and downloaded of all WGO guidelines. In 2017, under the leadership of Prof. Francisco Guarner, MD PhD, this document was updated. Three current ISAPP board members were part of the process and ISAPP provided funding. See here.



ISAPP petitioned the United States Preventive Services Task Force to examine the role of probiotics in preventing antibiotic-associated diarrhea. They considered the petition, but didn’t feel it fit their mission.

ISAPP petitioned American Academy of Family Physicians to consider reviewing the evidence for probiotics for AAD to include in their evidence-based guidelines. This is under consideration.

After attending 2017 ISAPP, Dr. Claire Merrifield BSc MBBS PhD led an effort to have NICE Clinical Knowledge Summaries mention probiotics for AAD in an effort to get local groups to adopt guidelines. This has met with limited success. See here.


CME or CE activities

On April 17, 2018, Merenstein and Mary Ellen Sanders PhD served as faculty for a CME-eligible webinar sponsored by Medscape on “Navigating the World of Probiotics. Helping Patients Make Good Choices”. The activity is available on Medscape’s website here.

In February 2018, Merenstein published a CE activity with the Pharmacy Times titled “The Expanding Health Benefits of Prebiotics and Probiotics”. See here

Upcoming in October 2018, Merenstein will present “Probiotics and the GI Tract. What Should a Busy Clinician Know” at the American Academy of Family Physicians Annual Conference. This conference is attended by over 4,000 physicians and is focused on clinical practice. The event, eligible for CME, will be recorded and made available after the live presentation.

ISAPP co-founder, Prof. Glenn Gibson has or will present 6 lectures over 2017 and 2018 on the topic of “The Learning Curve for Probiotics and Prebiotics.” These lectures are available for CME credit and are targeted to family doctors, gastroenterologists, pediatricians, and dieticians in the UK.

Numerous CME presentations over 2017-2018 have been given by ISAPP board members:

M.D. Cabana:

  • “Probiotics: Friend or Folly?”  American Academy of Pediatrics National Conference and Exhibition. Chicago, IL. September 17, 2017.  The audience was about 450-500 clinicians.
  • “Probiotics in Primary Care Pediatrics: Diarrhea, Colic & Eczema.” American Academy of Pediatrics California Chapter 1 Meeting. 300 clinicians
  • “Probiotics for Colic?” Zuckerberg San Francisco General Hospital. Department of Pediatrics Grand Rounds. San Francisco, CA.
  • “Probiotic Interventions for Colic” UCSF Benioff Children’s Hospital, Oakland.
  1. Reid:
  • “Effects and importance of microbiota on urogenital health in women.” 16th Annual Congress of Gynecology and Obstetrics, Antalya, Turkey. 300 obstetricians and gynecologists.
  • “Probiotics to whom for what?” Health World Ltd International Congress Natural Medicine 2017, Hunter Valley, New South Wales, Australia,.601 healthcare practitioners and naturopaths.
  • “The microbiome and how it relates to maternal/newborn care.” The Graham Chance Lectureship, Perinatal Research Day, London, ON. 100 neonatologists and pediatric experts.
  • “Microbes and the brain.” Integrative Healthcare Symposium, New York City. 500 naturopaths and various specialists.
  • “Probiotics and detoxification.” Environmental Health Symposium, Scottsdale, Arizona, 8th April. 500 naturopaths and various specialists.



On June 28, ISAPP co-founder, Prof. Glenn Gibson, will present a webinar along with Profs. Ted Dinan and Ian Rowland titled “Why is everybody talking about gut microbiota?” Sponsored by the British Nutrition Foundation, this webinar will target healthcare professionals in the UK and Europe. See here.


Publications in clinical journals

Several ISAPP board members

  • Evidence-Based Probiotic Use in Family Medicine. Submitted, Journal of Family Practice. Merenstein/Sanders/Tancredi
  • Probiotics for Human Use. In press, Nutrition Bulletin. Sanders/Merenstein/Hutkins/Merrifield
  • Probiotics and prebiotics in intestinal health and disease: from biology to the clinic. Invited review in preparation, Nature Reviews Gastroenterology and Hepatology. Gibson/Reid/Sanders/Merenstein
  • Clinical perspectives of prebiotics and synbiotics. In preparation, Gastroenterology. Gibson/Quigley


Featured on




  • What is a probiotic?
  • Health benefits of probiotics
  • Are all probiotics the same?
  • How to choose a probiotic


General guidelines for choosing probiotics and prebiotics

Some initiatives that Merenstein championed were a direct result of ideas generated during the discussion group he led during the 2017 ISAPP meeting in Chicago.


Image courtesy of

ISAPP board members share expertise in probiotic workshop in Buenos Aires

ISAPP board members, Prof. Seppo Salminen and Dr. Mary Ellen Sanders, along with over a dozen other renowned experts from the Southern Cone, Europe and Canada, participated in a workshop in Buenos Aires organized by Ricardo Weill of Instituto Danone Cono Sur April 26-27, 2018. The purpose of the workshop was two-fold. One goal was to share current science about probiotics with each other and with Codex Alimentarius and regulators from Argentina, to encourage a science-based approach to global probiotic standards that may end up with a draft of guidelines to be considered by the Codex Alimentarius late this year. Secondly, the intent is to convert each of the presentation topics into a chapter for a Spanish and English-language book to be published in the fall.

Two experts, Drs. Gabriel Vinderola and Rocio Martin, who participated in this meeting, will also serve as invited experts to the 2018 ISAPP meeting in Singapore June 5-6.

The concepts advanced by ISAPP in its papers on the scope and use of the term ‘probiotic’ and on the concept of core benefits and its regulatory implications were featured at this meeting. “The meeting was organized by Instituto Danone but it was devoid of all commercial content,” said Salminen.

vinderola in vitro blog

The need to improve in vitro testing of future probiotics

By Prof. Gabriel Vinderola, Instituto de Lactología Industrial (INLAIN, UNL-CONICET), National University of Litoral, Argentina and Prof. Seppo Salminen, Functional Foods Forum, Faculty of Medicine, University of Turku, Finland

In a recent review we compared the in vitro tests for probiotics to the in vivo studies to observe if correlations exist.

Lactobacilli and bifidobacteria have been traditionally accepted as probiotics with the basis of their long history of safe use and reported benefits. However, new species, some of them never previously consumed, are being proposed as probiotic candidates. Some basic tests have been suggested for probiotic candidates, but there is a lack of standardized in vitro protocols for the selection of new strains of probiotics. Additionally, safety assessment of new species may have to cover aspects never hitherto considered.

Vinderola and coworkers reviewed the common in vitro selection tests such as exposure to low pH and bile salts, adherence to intestinal mucus or cell lines and prokaryotic-eukaryotic co-cultures that have been traditionally used to predict the functional properties of probiotics.  At the end, the correlation of in vitro results with in vivo performance remained ambiguous. This poses challenges to research as newly proposed probiotics include often novel species never hitherto administered to humans.

The question of safety has been handled by the European QPS system and the US GRAS notifications but questions on efficacy, particularly concerning health claims, would benefit from predictive in vitro tests. These appear to predict more technological properties than safety and efficacy or health benefits.

New standardized systems need to be developed along with detailed sequencing information to be able to predict novel probiotic properties before they are tested in expensive human intervention studies. If the predictive capacity of in vitro tests fails, many potential probiotics will be left on the way from the laboratory to the application in humans and animals.

The lack of standardized protocols for in vitro and in vivo studies hampers comparison of the potential of new species and strains. There is thus a need to conduct selection of potential probiotics in a more robust manner and to focus on well-defined in vitro and in vivo (animal) studies able to predict health benefits that must still be confirmed in human interventions studies with the smallest possible error margin.

For additional perspective on this issue, see blog by Dr. Mary Ellen Sanders: Probiotic Screening: Are in vitro Tests Informative?



Reference: Vinderola G, Gueimonde M, Gomez-Gallego C, Delfredico L, Salminen S. Correlation between in vitro and in vivo assays in selection of probiotics from traditional species of bacteria. Trends in Food Sci Tech 2017: 68:83-90.

reid probiotics definition

You’d think we’d know probiotics by now

Prof. Gregor Reid, PhD MBA, Lawson Research Institute, University of Western Ontario, Canada

When I took my MBA, it was primarily to understand business and its relationship with science. I thought I learned quite a lot, but some things puzzle me to this day. Marketers know that messages are more effective when repeated. But, a guy called Thomas Smith (maybe related to Scotland’s famous Adam Smith who pioneered political economy, whatever that means!) wrote a guide in 1885 (yes that long ago!) called “Successful Advertising,” that noted:

The 1st time people see or read something, they don’t see it.
The 2nd time, they don’t notice it.
The 3rd time, they are aware that it is there.
The 4th time, they have a fleeting sense that they’ve seen it before.
The 5th time, they actually read the ad.
The 6th time, they thumb their nose at it.
The 7th time, they get a little irritated with it.
The 8th time, they think, “Here’s that confounded ad again.”
The 9th time, they wonder if they’re missing out on something.
The 10th time, they ask their friends or neighbors if they’ve tried it.
The 11th time, they wonder how the company is paying for all these ads.
The 12th time, they start to think that it must be a good product.
The 13th time, they start to feel the product has value.
The 14th time, they start to feel like they’ve wanted a product like this for a long time.

This goes on and on. It made me think about the definition and interpretation of probiotics. The version published in 2001 through two large respected organizations (WHO and UN FAO) has pretty much been universally accepted, and again reiterated in 2014 in a highly prestigious journal. That article is widely cited, so you’d think people would get it, right? They’d know what a probiotic is and what it’s not, right?

Yet, I speak at events around the world, and the same things keep coming back. Whether it is the 6th or 7th response (thumbing noses or being a little irritated) or a speaker confidently talking about probiotics and getting most of it completely wrong, I have scratched my head to the point my hair is falling out (a good research topic if someone would like to investigate this correlation). I even told a first year dentistry class of 55 students three times that the definition of probiotics would be an exam question. Only 8 got it correct!

I went back to the literature, as all scientists do, and asked the question “Why can’t people see what’s right in front of them?” It turns out either they believe you don’t have the answer, or you can’t have the answer, or you can’t have the answer right here and now, or they believe the answer needs to look like something else. This has a name – it’s called a schotoma – which seems appropriate, like people taking a shot at probiotics, or taking a shot at defining it, or providing their version of what it is.

With my hair now almost as thin as Glenn Gibson’s, I’m at a loss. Probiotics are not dead, not undefined/unstudied fermented foods, not in you unless you’ve taken them, not synonymous with “acidophilus”. They don’t typically colonize and they don’t have to be isolated from a human to work for humans. Products with lots of strains or a huge dose are not necessarily better products.

If you want to find the right probiotic for you, too often your doctor or health shop worker doesn’t give the best advice, because they haven’t read the articles. You should go or and find something suitable for your needs. If you want some good general guidance, check out ISAPP infographics and ISAPP videos. If you are a company, don’t call your product a probiotic unless the contents have been tested in humans at the dose you are delivering at end of shelf-life. Call it strains of lactobacilli or something along those lines. Not being on one of these charts might be a sign that you’ve not done the needed work to call your product a probiotic.

But hey, maybe you need to read Thomas Smith’s guide. Probiotics are really quite simple. But, then again it’s only the hundredth time I’ve said that.

As for prebiotics, I’ll let someone else go bald on that one.

probiotics larson photo

Probiotics: the importance of the complete product

February 11, 2018. By Dr. Olaf F.A. Larsen, Assistant Professor (0.2 FTE) at Athena Institute, VU University Amsterdam, The Netherlands, and Science Manager at Yakult Netherlands.

Probiotics are, according to the WHO and later updated by a consensus panel convened by ISAPP, defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”. Most scientific literature ties probiotic properties to individual strains, although evidence suggests that some health benefits may generalize to the species or genus level. Another important factor in how a probiotic performs is the type of matrix (e.g., a milk drink) that carries the probiotic. Indeed, many successful commercial probiotic products are largely defined by both the probiotic contained and the final product format. A plethora of probiotic products are available, ranging from fermented milks/yogurts, cereal products, juices and freeze-dried products (powders and pills). Some products claim to be probiotic but lack substantiation, such as “probiotic” pizzas and mattresses. It is likely that the probiotic properties are not solely determined by the probiotic strain itself, but also by the harbouring matrix. Hence, in order to fully understand the parameters that drive functionality of a specific probiotic, the total product should be evaluated.

Recently, the influence of the matrix on measures of probiotic functionality was reviewed. The data suggest that the matrix impacts several parameters, including number of viable probiotic microorganisms present in the product through shelf life and survival of the probiotic through the gastrointestinal tract. As an example, the number of viable microorganisms in the product as a function storage time can be profoundly different depending on the combination of probiotic strains and matrices used. Some products in which lyophilized probiotics are incorporated into a peanut butter matrix can have storage times up to 50 weeks. Whey proteins present in milk may improve gastrointestinal tract survival. Therefore, one should be aware that it is likely that viability of the probiotic will be impacted by the carrier matrix.

Another way that matrix can be important is through delivery of additional beneficial substances. For example, milk products contain various vitamins, calcium and high quality protein. In the case of a fermented probiotic product, the fermentation process may yield functional substances such as antihypertensive peptides. These effects can be considered as “additional benefits” of the matrix, beyond the impact of matrix on probiotic survival both in the product and in your body.

The body of scientific evidence falls short, however, of proving the importance of matrix on health endpoints. For a given amount of probiotics delivered, we lack comparative studies that prove that the end-benefit of one carrier matrix is better than another. Many supportive studies suggest that this will be the case, but until head-to-head human studies are conducted, we don’t know for sure.

Given the impact the matrix exerts on probiotic survival, and the possible effect on probiotic effectiveness, keep in mind the importance of efficacy studies conducted on the complete probiotic product. We need more research to fully understand the role of matrix on probiotic effectiveness, but the strongest evidence comes from studies conducted on the complete probiotic product.

Figure: Determinants of probiotic product parameters (adapted from Flach et al. 2017). Mark B. van der Waal is gratefully acknowledged for producing the artwork.

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For another perspective see Does the delivery format affect probiotic efficacy?, March 28, 2018 by Mary Ellen Sanders.