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Episode 6: Mechanisms of action for probiotics

/in Podcast, Season One /by KC

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The Science, Microbes & Health Podcast 

This podcast covers emerging topics and challenges in the science of probiotics, prebiotics, synbiotics, postbiotics and fermented foods. This is the podcast of The International Scientific Association for Probiotics and Prebiotic (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

Mechanisms of action for probiotics, with Prof. Sarah Lebeer

Episode summary:

In this episode, the ISAPP hosts speak with Prof. Sarah Lebeer of University of Antwerp, Belgium, to bring clarity to a commonly misunderstood topic: probiotic mechanisms of action. They discuss how probiotic mechanisms are often multi-factorial and difficult to unravel scientifically. Nevertheless, Prof. Lebeer describes five distinct mechanisms of action by which a probiotic may benefit a host.

See ISAPP’s other podcast episode on mechanisms of action, with Prof. Maria Marco: Why mechanistic research on probiotics is captivating and important.

Key topics from this episode:

  • Probiotics are live microorganisms with documented health benefits; their mode of action is multifactorial.
  • Mechanism of action is crucial in the probiotic field. This knowledge helps scientists understand how probiotics interact with the human host and the microbiota. However, even if mode of action for a strain is known it can be difficult to translate it into measurable outcomes for the host.
  • Probiotics can benefit health by five main mechanisms of action applicable at different body sites (gut, vagina, skin, nose, etc.):
    1. Modulation of microbe-microbe interactions by inhibiting pathogens and promoting beneficial microbes. This is based on the production of metabolically active molecules, such as lactic acid. 
    2. Enhancement of mucosal barrier function through interaction with epithelial cells, promoting the integrity of the barrier. 
    3. Modulation of immune responses by interacting with various immune cells. Interaction with the immune cells is also the clearest strain-specific capacity of probiotics.
    4. Modulation of metabolic responses by modulating insulin resistance or cholesterol metabolism. This mode of action is novel, and research is emerging.
    5. Modulation of neurological signaling pathways. This is also a novel mode of action with new evidence building up.
  • Postbiotics can have similar modes of action, provided the active molecules are not inactivated.

 

Episode links:

The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic

 

Graphical summary of 5 main mechanisms of action for probiotics

(Image by Sarah Lebeer. Image copyright.)

 

Additional resources:

Current status of research on probiotic and prebiotic mechanisms of action. ISAPP blog
Importance of understanding probiotic mechanisms of action. ISAPP blog

 

About Prof. Sarah Lebeer:

Sarah Lebeer is a research professor at the Department of Bioscience Engineering of the University of Antwerp, Belgium. She has studied bioscience engineering, with a specialisation in cell and gene technology/food & health and obtained her Master at KU Leuven (Belgium). In 2008, she obtained a PhD degree with a topic on the mode of action of gastro-intestinal probiotics in inflammatory bowel diseases and a scholarship in the team of Prof. Jos Vanderleyden (KU Leuven). After a postdoc on the interaction between lactobacilli, viruses and mucosal immunology, in November 2011, she was offered a tenure track position at the University of Antwerp. Since then, she is leading the Laboratory for Applied Microbiology and Biotechnology of the ENdEMIC research group.

In 2020, she was awarded with an ERC Starting Grant that enables her to gain more in-depth knowledge of the evolutionary history and ecology of lactobacilli (https://www.lebeerlab.com). This rationale was also an important driving force to revise the Lactobacillus genus taxonomy with  a large international consortium. Within the ERC project, Sarah has also launched the Isala citizen-science project to gain new insights in the role of vaginal lactobacilli for women’s health (https://isala.be). Since 2018, Sarah is an academic board member of the International Scientific Association on Probiotics and Prebiotics (www.isappscience.org). Communicating about beneficial microbes and probiotics for experts and laymen is an important inspiration for her daily work. 

Episode 4: Weighing evidence for probiotic interventions: Perspectives of a primary care physician

/in Podcast, Season One /by KC

Podcast: Play in new window | Download

Subscribe: Apple Podcasts | Google Podcasts | Spotify | RSS

The Science, Microbes & Health Podcast 

This podcast covers emerging topics and challenges in the science of probiotics, prebiotics, synbiotics, postbiotics and fermented foods. This is the podcast of The International Scientific Association for Probiotics and Prebiotic (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

Weighing evidence for probiotic interventions: Perspectives of a primary care physician, with Prof. Dan Merenstein, MD

Episode summary:

In this episode, the ISAPP host Prof. Dan Tancredi discusses evidence for probiotic interventions with Prof. Dan Merenstein, MD, a family medicine researcher based at Georgetown University. They discuss what it means to practice evidence-based medicine, and what kind of evidence clinicians should look for when deciding whether an intervention is appropriate. Prof. Merenstein shares how probiotic evidence has strengthened in the past few decades, and gives tips on what to look for in a probiotic intervention study.

Key topics from this episode:

  • What is evidence-based medicine, and why is it important to practice it? Evidence-based medicine provides proper care for patients at the appropriate time by focusing on the existing evidence provided by clinical studies.
  • What is evidence, and how do we obtain a high level of evidence for probiotics? Evidence should come from well-designed clinical studies. Animal and in vitro studies provide supportive preclinical information and mechanistic insights.
  • The quality of probiotic research has improved in recent years. Compared with decades ago, studies are more likely to be high quality and more likely to be properly-powered. Such studies have provided a clearer sense of the circumstances under which probiotics may – or may not – provide health benefits.
  • What is the proper way to report clinical trials in the probiotic field? Focus on the rules for conducting a clinical trial: for example, CONSORT (see below). Compliance is also important for good outcomes.
  • How can a clinician evaluate if a patient should use an intervention? The focus should be on the evidence for each intervention, the potential harm of the intervention, and the positive and negative outcomes.
  • Evidence-based medicine also needs to account for regional differences and where the clinical studies have been performed. Evidence about probiotic effects needs to account for microbiome differences and lifestyle differences between countries.
  • For which indications do we now have actionable evidence for probiotic use?
    • Use of certain probiotics together with antibiotic treatment to prevent antibiotic-associated diarrhea
    • Use of an L. reuteri strain to reduce crying time for infants suffering from colic
    • Certain probiotics can help prevent traveler’s diarrhea or treat acute pediatric infectious diarrhea.
    • Probiotics to help with endpoints such as weight loss and metabolic syndrome, for autism and gut-brain indications, for skin conditions such as eczema and acne, and inflammatory bowel disease are active areas of research and soon scientists will have more answers.
  • Probiotic research is improving. Patients are using probiotics, and they are aware of the benefits of probiotics – Prof. Merenstein estimates that 80% of his patients are taking a probiotic. The job of the doctor is to get them to use probiotics in an evidence-based manner.

 

Episode links:

CONSORT (Consolidated Standards of Reporting Trials) establishes a well-accepted, evidence-based, minimum set of recommendations for reporting randomized trials.
IPDMA (individual patient data meta-analysis) – see this Sung et al. paper on infantile colic and L. reuteri
BB12: Bifidobacterium animalis subsp. lactis BB-12, a well-studied probiotic. See this paper.
A priori: without prior knowledge

 

Additional resources:

The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic

 

About Prof. Dan Merenstein:

Dr. Daniel Merenstein is a Professor with tenure of Family Medicine at Georgetown University, where he also directs Family Medicine research. Dr. Merenstein has a secondary appointment in the undergraduate Department of Human Science, in the School of Nursing and Health Studies. Dr. Merenstein teaches two undergraduate classes, a research capstone and a seminar class on evaluating evidence based medical decisions. He has been funded by the NIH, USDA, Foundations and Industry, for grants over $100 million. Dr. Merenstein is the President of the board of directors of the International Scientific Association of Probiotics and Prebiotics.

The primary goal of Dr. Merenstein’s research is to provide answers to common clinical questions that lack evidence and improve patient care. Dr. Merenstein is a clinical trialist who has recruited over 2,100 participants for 10 probiotic trials since 2006. He is an expert on probiotics, antibiotic stewardship in outpatient settings and also conducts HIV research in a large women’s cohort. He sees patients in clinic one day a week.

Probiotics vs. prebiotics: Which to choose? And when?

/in Consumer Blog, ISAPP Science Blog /by KC

By Dr. Karen Scott, PhD, Rowett Institute, University of Aberdeen, Scotland

As consumers we are constantly bombarded with information on what we should eat to improve our health. Yet the information changes so fast that it sometimes seems that what was good for us last week should now be avoided at all costs!

Probiotics and prebiotics are not exempt from such confusing recommendations, and one area lacking clarity for many is which of them we should pick, and when. In this blog I will consider the relative merits of probiotics and prebiotics for the gut environment and health.

By definition, both probiotics and prebiotics should ‘confer a health benefit on the host’. Since an improvement in health can be either subjective (simply feeling better) or measurable (e.g. a lowering in blood pressure) it is clear that there is not a single way to define a ‘health benefit’. This was discussed nicely in a previous blog by Prof Colin Hill.

Although consumption of both probiotics and prebiotics should provide a health benefit, this does not mean that both need to act through the gut microbiota. Prebiotics definitively need to be selectively utilised by host microorganisms – they are food for our existing microbiota. However, depending on the site of action, this need not be the gut microbiota, and prebiotics targeting other microbial ecosystems in or on the body are being developed. Traditionally prebiotics have specifically been used to boost numbers of gut bacteria such as Bifidobacterium and the Lactobacilliaceae family, but new prebiotics targeting different members of the gut microbiota are also currently being researched.

Probiotics are live bacteria and despite a wealth of scientific evidence that specific probiotic bacterial strains confer specific health benefits, we often still do not know the exact mechanisms of action. This can make it difficult both to explain how or why they work, and to select new strains conferring similar health benefits. Many probiotics exert their effects within the gut environment, but they may or may not do this by interacting with the resident gut microbiota. For instance probiotics that reduce inflammation do so by interacting directly with cells in the mucosal immune system. Yet strains of lactobacilli (see here for what’s included in this group of bacteria) may do this by modulating cytokine production while Bifidobacterium strains induce tolerance acquisition. These very different mechanisms are one reason why mixtures containing several probiotic species or strains may in the end prove the most effective way to improve health. On the other hand, some probiotics do interact with the resident gut microbes: probiotics that act by inhibiting the growth of pathogenic bacteria clearly interact with other bacteria. Sometimes these may be potential disease-causing members of the resident microbiota, normally kept in check by other commensal microbes that themselves have become depleted due to some external impact, and some may be incoming pathogens. Such interactions can occur in the gut or elsewhere in the body.

This brings me back to the original question, and one I am frequently asked – should I take a probiotic or a prebiotic? The true and quick answer to this question is ‘it depends’! It depends why you are asking the question, and what you want to achieve. Let’s think about a few possible reasons for asking the question.

I want to improve the diversity of my microbiota. Should I take a prebiotic or a probiotic?

My first reaction was that there is an easy answer to this question – a prebiotic. Prebiotics are ‘food’ for your resident bacteria, so it follows that if you want to improve the diversity of your existing microbiota you should take a prebiotic. However, in reality this is too simplistic. Since prebiotics are selectively utilised by a few specific bacteria within the commensal microbiota to provide a health benefit, taking a prebiotic will boost the numbers of those specific bacteria. If the overall bacterial diversity is low, this may indeed improve the diversity. However, if the person asking the question already has a diverse microbiota, although taking one specific prebiotic may boost numbers of a specific bacterium, it may not change the overall diversity in a measurable way. In fact the best way to increase the overall diversity of your microbiota is to consume a diverse fibre-rich diet – in that way you are providing all sorts of different foods for the many different species of bacteria living in the gut, and this will increase the diversity of your microbiota.  Of course, if you already consume a diverse fibre-rich diet your microbiota may already be very diverse, and any increased diversity may not be measurable.

I want to increase numbers of bifidobacteria in my microbiota. Should I take a prebiotic or a probiotic?

Again, I initially thought this was easy to answer – a prebiotic. There is a considerable amount of evidence that prebiotics based on fructo-oligosaccharides (FOS or inulin) boost numbers of bifidobacteria in the human gut. But this is only true as long as there are bifidobacteria present that can be targeted by consuming suitable prebiotics. Some scientific studies have shown that there are people who respond to prebiotic consumption and people who do not (categorised as responders and non-responders). This can be for two very different reasons. If an individual is devoid of all Bifidobacterium species completely, no amount of prebiotic will increase bifidobacteria numbers, so they would be a non-responder. In contrast if someone already has a large, diverse bifidobacteria population, a prebiotic may not make a meaningful impact on numbers – so they may also be a non-responder.

However, for those people who do not have any resident Bifidobacterium species, the only possible way to increase them would indeed be to consume a probiotic- specifically a probiotic containing one or several specific Bifidobacterium species. Consuming a suitable diet, or a prebiotic alongside the probiotic, may help retention of the consumed bifidobacteria, but this also depends on interactions with the host and resident microbiota.

I want to increase numbers of ‘specific bacterium x’ in my microbiota. Should I take a prebiotic or a probiotic?

The answer here overlaps with answer 2, and depends on the specific bacterium, and what products are available commercially, but the answer could be to take either, or a combination of both – i.e. a synbiotic.

If bacterium x is available as a probiotic, consuming that particular product could help. If bacterium x has been widely researched, and the specific compounds it uses for growth have been established, identifying and consuming products containing those compounds could boost numbers of bacterium x within the resident microbiota. Such research may already have identified combination products – synbiotics – that could also be available.

One caveat for the answers to questions 2 and 3 is that probiotics do not need to establish or alter the gut microbiota to have a beneficial effect on health. In fact, a healthy large intestine has a microbial population of around 1011-1012 bacterial cells per ml, or up to 1014 cells in total, while a standard pot of yogurt contains 1010 bacterial cells (108 cells/ml). Assuming every probiotic bacterial cell reaches the large intestine alive, they would be present in a ratio of 1: 10,000. This makes it difficult for them to find a specific niche to colonise, so consuming a probiotic may not “increase numbers of ‘specific bacterium x’ in my microbiota”, but this does not mean that the function of the probiotic within the gut ecosystem would not provide a health benefit. Many probiotics act without establishing in the microbiota.

I’ve been prescribed antibiotics. Should I take a prebiotic or a probiotic?

In this case the answer is clear cut – a probiotic.

There is a lot of evidence that consumption of probiotics can alleviate symptoms of, or reduce the duration of, antibiotic associated diarrhoea. From what we know about mechanisms of action, consumption of antibiotics kills many resident gut bacteria, reducing the overall bacterial population and providing an opportunity for harmful bacteria to become more dominant. Consuming certain probiotics can either help boost bacterial numbers in the large intestine, preventing the increased growth in pathogenic bacteria until the resident population recovers, or can increase production of short chain fatty acids, decreasing the colonic pH, preventing growth of harmful bacteria. Ideally probiotics would be taken alongside antibiotics, from day 1, to avoid the increase in numbers of the potentially harmful bacteria in the first place. This has been shown to be more effective. Consuming the probiotic alongside prebiotics that could help the resident microbiota recover more quickly may be even more effective. Even if you’ve already started the course of antibiotics, it’s not too late to start taking probiotics to reduce any side-effects. Always remember to complete taking the course of antibiotics as prescribed.

 

 

Putting all of this together to answer the initial question of whether it’s better to take probiotics or prebiotics, a better answer may in fact be take both to cover the different effects each has, maximising the benefit to health. There are specific times when probiotics are better, and other times when prebiotics are better, and consuming both together may make each more effective. In any case care has to be taken to consume a product that has been confirmed through robust studies to have the specific benefit that is required.

 

Episode 3: The science of fermented foods, part 2

/in Podcast, Season One /by KC

Podcast: Play in new window | Download

Subscribe: Apple Podcasts | Google Podcasts | Spotify | RSS

The Science, Microbes & Health Podcast 

This podcast covers emerging topics and challenges in the science of probiotics, prebiotics, synbiotics, postbiotics and fermented foods. This is the podcast of The International Scientific Association for Probiotics and Prebiotic (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

The science of fermented foods, part 2, with Prof. Bob Hutkins

Episode summary:

Before listening to this episode, it’s recommended that you check out episode #1, The science of fermented foods, Part 1. In this episode, the hosts continue their discussion of fermented foods with Prof. Bob Hutkins, University of Nebraska – Lincoln. Prof. Hutkins elaborates on how the microbes associated with fermented foods may confer health benefits, as well as how food scientists choose strains for fermentation. He emphasizes how the live microbes in fermented foods differ from probiotics.

Key topics from this episode:

  • Why working in the field of fermented foods is exciting and rewarding
  • The challenges for scientists, especially when it comes to designing clinical studies with various fermented foods
  • The benefits of fermented foods – from being safe as well as nutritious, to the health benefits that live microbes present in the foods can provide
  • How microbes are selected for fermentation; companies focus on strain performance – i.e., good growth and survival to preserve the food and provide a desired flavor and texture
  • The activities of live microbes present in fermented foods, from initiating the fermentation process to benefiting human health
  • The differences between probiotics and live microbes in fermented foods
  • How live microbes in fermented foods might affect your gut microbiota and why some scientists believe that fermented foods are important for getting regular doses of live microbes

 

Episode links:

Microbiology and Technology of Fermented Foods, 2nd Ed., by Robert W. Hutkins
The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods
The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic
Gut-microbiota-targeted diets modulate human immune status, study by Stanford researchers

 

Additional resources:

Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics.
Postbiotics. ISAPP infographic
Fermented foods. ISAPP infographic
What are fermented foods? ISAPP video
Do fermented foods contain probiotics? ISAPP blog post
How are probiotic foods and fermented foods different? ISAPP infographic
Are fermented foods probiotics? Webinar by Mary Ellen Sanders, PhD

 

About Prof. Bob Hutkins:

Bob Hutkins is the Khem Shahani Professor of Food Microbiology at the University of Nebraska. He received his Ph.D. from the University of Minnesota and was a postdoctoral fellow at Boston University School of Medicine. Prior to joining the University of Nebraska, he was a research scientist at Sanofi Bio Ingredients.

The Hutkins Lab studies bacteria important in human health and in fermented foods. His group is particularly interested in understanding factors affecting persistence and colonization of probiotic bacteria in the gastrointestinal tract and how prebiotics shift the intestinal microbiota and metabolic activities. The lab also conducts clinical studies using combinations of pro- and prebiotics (synbiotics) to enhance health outcomes. More recently we have developed metagenome-based models that can be used in personalized nutrition.

Professor Hutkins has published widely on probiotics, prebiotics, and fermented foods and is the author of the recently published 2nd edition of Microbiology and Technology of Fermented Foods.

Episode 2: Why mechanistic research on probiotics is captivating and important

/in Podcast, Season One /by KC

Podcast: Play in new window | Download

Subscribe: Apple Podcasts | Google Podcasts | Spotify | RSS

The Science, Microbes & Health Podcast 

This podcast covers emerging topics and challenges in the science of probiotics, prebiotics, synbiotics, postbiotics and fermented foods. This is the podcast of The International Scientific Association for Probiotics and Prebiotic (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

Why mechanistic research on probiotics is captivating and important, with Prof. Maria Marco

Episode summary:

In this episode, the ISAPP hosts discuss probiotic mechanisms of action with Prof. Maria Marco, University of California, Davis. Prof. Marco is a well-known probiotic researcher with special expertise in food-associated lactobacilli. Here she explains how studying probiotics in food science can lead to fundamental insights in biology. She shares why it’s important to understand probiotic mechanisms of action, and describes how scientists go about identifying which compounds or pathways are important for probiotic health effects.

Key topics from this episode:

  • The search for probiotic mechanisms of action: why this research is essential and the added value of this type of research for the end consumer.
  • What we now understand about probiotic mode of action: probiotic mode of action for different strains is mediated by multiple working mechanisms, from cell-wall-associated molecules to bacteriocin production and metabolite synthesis.
  • How researchers set the stage for studying probiotics’ mode of action, from large scale screening, to molecular techniques focusing on single molecules and genome comparisons between strains.
  • Whether we need to apply something similar to Koch’s postulates when talking about the effects of probiotics.
  • The potential effects of food or delivery matrix on a probiotic mechanism of action.  
  • What we can learn from the postbiotic research, which can help inform probiotic mechanisms of action.
  • The most exciting developments in probiotic mode of action research in the past 10 years and the future of this area of research.

 

Episode links:

The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic
Prof. Marco refers to two of her mentors, Willem De Vos and Michiel Kleerebezem
See this overview of Koch’s postulates

 

Additional resources:

Bacterial genes lead researchers to discover a new way that lactic acid bacteria can make energy and thrive in their environments, ISAPP blog post featuring recent work from Prof. Marco’s lab

 

About Prof. Maria Marco:

Maria Marco is a Professor in the Department of Food Science and Technology and Chair of the Food Science Graduate Group at the University of California, Davis. She received her PhD in microbiology from the University of California, Berkeley and then was a postdoc and project leader at NIZO Food Research, The Netherlands. Dr. Marco has 20 years’ experience investigating fermented foods, probiotics, and diet-dependent, host-microbe interactions in digestive tract. Her laboratory at UC Davis is broadly engaged in the study of food and intestinal microbiomes and the ecology and genetics of lactic acid bacteria. 

Episode 1: The science of fermented foods, part 1

/in Podcast, Season One /by KC

Podcast: Play in new window | Download

Subscribe: Apple Podcasts | Google Podcasts | Spotify | RSS

The Science, Microbes & Health Podcast 

This podcast covers emerging topics and challenges in the science of probiotics, prebiotics, synbiotics, postbiotics and fermented foods. This is the podcast of The International Scientific Association for Probiotics and Prebiotic (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

The science of fermented foods, part 1, with Prof. Bob Hutkins

Episode summary:

The hosts discuss fermented foods with Prof. Bob Hutkins, University of Nebraska – Lincoln. Prof. Hutkins wrote a popular textbook on fermented foods and has had a 40-year career in fermentation science. He shares why he ended up in fermentation science, as well as how fermented foods are made and how important live microbes are for their health benefits.

Key topics from this episode:

  • What fermented foods are
  • The scientific consensus definition published by ISAPP
  • Fermentation processes and practices used in early times and still used today
  • The benefits and safety of fermented foods, as well as the difference between fermentation and food spoilage
  • The live microbes present in fermented foods, how many are present, and their potential health benefits
  • Why some fermented foods have live microbes and others do not; and how even when live microbes are absent due to heat treatment, for example, these products may still be classified as fermented 
  • The differences between fermented foods, probiotics, and probiotic fermented foods

 

Episode links:

Microbiology and Technology of Fermented Foods, 2nd Ed., by Robert W. Hutkins
The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods
The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic
Synbiotics: Definitions, Characterization, and Assessment – ISAPP webinar featuring Prof. Bob Hutkins and Prof. Kelly Swanson

 

Additional resources:

Fermented foods. ISAPP infographic
What are fermented foods? ISAPP video
Do fermented foods contain probiotics? ISAPP blog post
How are probiotic foods and fermented foods different? ISAPP infographic
Are fermented foods probiotics? Webinar by Mary Ellen Sanders, PhD

 

About Prof. Bob Hutkins:

Bob Hutkins is the Khem Shahani Professor of Food Microbiology at the University of Nebraska. He received his Ph.D. from the University of Minnesota and was a postdoctoral fellow at Boston University School of Medicine. Prior to joining the University of Nebraska, he was a research scientist at Sanofi Bio Ingredients.

The Hutkins Lab studies bacteria important in human health and in fermented foods. His group is particularly interested in understanding factors affecting persistence and colonization of probiotic bacteria in the gastrointestinal tract and how prebiotics shift the intestinal microbiota and metabolic activities. The lab also conducts clinical studies using combinations of pro- and prebiotics (synbiotics) to enhance health outcomes. More recently we have developed metagenome-based models that can be used in personalized nutrition.

Professor Hutkins has published widely on probiotics, prebiotics, and fermented foods and is the author of the recently published 2nd edition of Microbiology and Technology of Fermented Foods.

New ISAPP Webinar: Fermented Foods and Health — Continuing Education Credit Available for Dietitians

/in News /by KC

Dietitians – along with many other nutritional professionals – often receive questions about consuming fermented foods for digestive health. But how strong is the evidence that fermented foods can improve digestive health?

ISAPP is pleased to work with Today’s Dietitian to offer a free webinar in which Hannah Holscher, PhD, RD, and Jennifer Burton, MS, RD, LDN will discuss the foundational elements of fermented foods, the role of microbes in fermentation, how they differ from probiotics and prebiotics, and how to incorporate fermented foods into client diets in an evidence-based manner. Participants will come away with a grasp of the scientific evidence that supports fermented food consumption. This activity is accredited by the Academy of Nutrition and Dietetics Commission on Dietetic Registration (CDR) for 1.0 CPEUs for dietitians.

The one-hour virtual event, titled “Fermented Foods and Health — Does Today’s Science Support Yesterday’s Tradition?”, was held April 20th, 2022, at 2:00 pm Eastern Time.

See the webinar recording here.

ISAPP and Today’s Dietitian also collaborated on a self-study activity titled “Evidence-based use of probiotics, prebiotics and fermented foods for digestive health”. This free activity, which provides more detail on the topic that the 1-hour webinar above, was approved by CDR to offer 2.0 CPEUs for dietitians and is available here through November 2023.

Improving the quality of microbiome studies – STORMS

/in ISAPP Science Blog /by KC

By Mary Ellen Sanders, PhD, ISAPP Executive Science Officer

In mid-March I attended the Gut Microbiota for Health annual meeting. I was fortunate to participate in a short workshop chaired by Dr. Geoff Preidis MD, PhD, a pediatric gastroenterologist from Baylor College of Medicine and Dr. Brendan Kelly MD, MSCE, an infectious disease physician and clinical epidemiologist from University of Pennsylvania. The topic of this workshop was “Designing microbiome trials – unique considerations.”

Dr. Preidis introduced the topic by recounting his effort (Preidis et al. 2020) to review evidence for probiotics for GI endpoints, including for his special interest, necrotizing enterocolitis (NEC). After a thorough review of available studies testing the ability of probiotics to prevent morbidity and mortality outcomes for premature neonates, he and the team found 63 randomized controlled trials that assessed close to 16,000 premature babies. Although the effect size for the different clinical endpoints was impressive and clinically meaningful, AGA was only able to give a conditional recommendation for probiotic use in this population.

Why? In part, because inadequate conduct or reporting of these studies led to reduced confidence in their conclusions. For example, proper approaches to mitigate selection bias must be reported. Some examples of selection bias include survival bias (where part of the target study population is more likely to die before they can be studied), convenience sampling (where members of the target study population are not selected at random), and loss to follow-up (when probability of dropping out is related to one of the factors being studied). These are important considerations that might influence microbiome results. If the publication on the trial does not clearly indicate how these potential biases were addressed, then the study cannot be judged as low risk of bias. It’s possible in such a study that bias is addressed correctly but reported incompletely. But the reader cannot ascertain this.

With an eye toward improving the quality and transparency of future studies that include microbiome endpoints, Dr. Preidis shared a paper by a multidisciplinary team of bioinformaticians, epidemiologists, biostatisticians, and microbiologists titled Strengthening The Organization and Reporting of Microbiome Studies (STORMS): A Reporting Checklist for Human Microbiome Research.

Dr. Preidis kindly agree to help the ISAPP community by answering a few questions about STORMS:

Dr. Preidis, why is the STORMS approach so important?

Before STORMS, we lacked consistent recommendations for how methods and results of human microbiome research should be reported. Part of the problem was the complex, multi-disciplinary nature of these studies (e.g., epidemiology, microbiology, genomics, bioinformatics). Inconsistent reporting negatively impacts the field because it renders studies difficult to replicate or compare to similar studies. STORMS is an important step toward gaining more useful information from human microbiome research.

One very practical outcome of this paper is a STORMS checklist, which is intended to help authors provide a complete and concise description of their study. How can we get journal editors and reviewers to request this checklist be submitted along with manuscripts for publication?

We can reach out to colleagues who serve on editorial boards to initiate discussions among the editors regarding how the STORMS checklist might benefit reviewers and readers of a specific journal.

How does this checklist differ from or augment the well-known CONSORT checklist?

Whereas the CONSORT checklist presents an evidence-based, minimum set of recommendations for reporting randomized trials, the STORMS checklist facilitates the reporting of a comprehensive array of observational and experimental study designs including cross-sectional, case-control, cohort studies, and randomized controlled trials. In addition to standard elements of study design, the STORMS checklist also addresses critical components that are unique to microbiome studies. These include details on the collection, handling, and preservation of specimens; laboratory efforts to mitigate batch effects; bioinformatics processing; handling of sparse, unusually distributed multi-dimensional data; and reporting of results containing very large numbers of microbial features.

How will papers reported using STORMS facilitate subsequent meta-analyses?

When included as a supplemental table to a manuscript, the STORMS checklist will facilitate comparative analysis of published results by ensuring that all key elements are reported completely and organized in a way that makes the work of systematic reviewers more efficient and more accurate.

I have been struck through the years of reading microbiome research that primary and secondary outcomes seem to be rarely stated up front. Or if such trials are registered, for example on clinicaltrials.gov, the paper does not necessarily focus on the pre-stated primary objectives. This approach runs the risk of researchers finding the one positive story to tell out of the plethora of data generated in microbiome studies. Will STORMS help researchers design more hypothesis driven studies?

Not necessarily. The STORMS checklist was not created to assess study or methodological rigor; rather, it aims to aid authors’ organization and ease the process of reviewer and reader assessment of how studies are conducted and analyzed.  However, if investigators use this checklist in the planning phases of a study in conjunction with sound principles of study design, I believe it can help improve the quality of human microbiome studies – not just the writing and reporting of results.

Do you have any additional comments?

One of the strengths of the STORMS checklist is that it was developed by a multi-disciplinary team representing a consensus across a broad cross-section of the microbiome research community. Importantly, it remains a work in progress, with planned updates that will address evolving standards and technological processes.  Anyone interested in joining the STORMS Consortium should visit the consortium website (www.stormsmicrobiome.org).

See related blog:   ISAPP take-home points from American Gastroenterological Association guidelines on probiotic use for gastrointestinal disorders

 

Bacterial genes lead researchers to discover a new way that lactic acid bacteria can make energy and thrive in their environments

/in ISAPP Science Blog /by KC

Lactic acid bacteria are an important group of bacteria associated with the human microbiome. Notably, they are also responsible for creating fermented foods such as sauerkraut, yogurt, and kefir. In the past two decades, culture-independent techniques have allowed scientists to sequence the genomes of these bacteria and discover more about their capabilities.

Researchers studying a type of lactic acid bacteria called Lactiplantibacillus plantarum found something unexpected: they contained genes for making energy in a way that had not been previously documented. Generally, living organisms obtain energy from their surroundings either by fermentation or respiration. L. plantarum have long been understood to obtain energy using fermentation, but the new genetic analysis found they had additional genes that were suited to respiration. Could they be using both fermentation and respiration?

ISAPP board member Prof. Maria Marco is a leading expert on lactic acid bacteria and their role in fermented foods and in human health. In her lab at University of California Davis, she decided to investigate why L. plantarum had genes equipping it for respiration. Her group recently published findings that show a new type of “hybrid” metabolism used by these lactobacilli.

Here is a Q&A with Prof. Marco about these exciting new findings.

What indicated to you that some of the genes in L. plantarum didn’t ‘belong’?

Organisms that use respiration normally require an external molecule that can accept electrons, such as oxygen. Interestingly, some microorganisms can also use solid electron acceptors located outside the cell, such as iron. This ability, called extracellular electron transfer, has been linked to proteins encoded by specific genes. L. plantarum had these genes, even though this species is known to use fermentation. We first learned about their potential function from Dr. Sam Light, now at the University of Chicago. Sam discovered a related pathway in the foodborne pathogen Listeria monocytogenes. Sam came across our research on L. plantarum because we previously published a paper showing that a couple of genes in this pathway are switched on in the mammalian digestive tract. We wondered what the proteins encoded by these genes were doing.

How did you set out to investigate the metabolism of these bacteria?

We investigated this hybrid metabolism in a variety of ways. Using genetic and biochemical approaches we studied the extent to which L. plantarum and other lactic acid bacteria are able to use terminal electron acceptors like iron. Our collaborators at Lawrence Berkeley National Lab and Rice University contributed vital expertise with their electrochemistry experiments, including making fermented kale juice in a bioelectrochemical reactor.

What did you find out?

We discovered a previously unknown method of energy metabolism in Lactiplantibacillus plantarum. This hybrid strategy blends features of respiration (a high NAD+/NADH ratio and use of a respiratory protein) with features of fermentation (use of endogenous electron acceptors and substrate-level phosphorylation).

We verified that this hybrid metabolism happens in different laboratory media and in kale juice fermentations. We also found that, in the complex nutritive environment of a kale juice fermentation, this hybrid metabolism increases the rate and extent of fermentation and increases acidification. Within the ecological context of the fermented food, this could give L. plantarum a fitness advantage in outcompeting other microorganisms. This could potentially be used to change the flavor and texture of fermented foods.

This discovery gives us a new understanding of the physiology and ecology of lactic acid bacteria.

Are there any indications about whether this energy-making strategy is shared by other lactic acid bacteria?

Some other fermentative lactic acid bacteria also contain the same genetic pathway. It is likely that we are just at the tip of the iceberg learning about the extent of this hybrid metabolism in lactobacilli and related bacteria.

Your finding means there is electron transfer during lactic acid bacteria metabolism. What does this add to previous knowledge about bacterially-produced ‘electricity’?

Certain soil and aquatic microbes have been the focus of research on bacterially-produced electricity. We found that by giving L. plantarum the right nutritive environment, it can produce current to the same level as some of those microbes. We believe there is potential to apply the findings from our studies to better inform food fermentation processes and to guide fermentations to generate new or improved products. Because strains of L. plantarum and related bacteria are also used as probiotics, this information may also be useful for understanding their molecular mechanisms of action in the human digestive tract.

How might this knowledge be applied in practice?

Our findings can lead to new technologies which use lactic acid bacteria to produce healthier and tastier fermented foods and beverages. Because this hybrid metabolism leads to efficient fermentation and a larger yield, it could also help minimize food waste. We plan to continue studying the diversity, expression, and regulation of this hybrid metabolism in the environments in which these bacteria are found.

ISAPP awards the Glenn Gibson Early Career Research Prize to two diet and gut health researchers

/in ISAPP Science Blog, News /by KC

The ISAPP board of directors is pleased to announce that the 2022 Glenn Gibson Early Career Research Prize has been awarded to two promising researchers in the field of probiotics, prebiotics and related substances.

Dr. Martin Laursen, Senior Researcher at the National Food Institute, Technical University of Denmark, has demonstrated excellence in his work on the impact of probiotics and human milk oligosaccharides on infant gut microbiota and health. Dr. Eirini Dimidi, Lecturer at King’s College in London, UK, has carried out meaningful work on probiotics, prebiotics, and fermented foods and their impact on constipation.

The award criteria stipulated that the researchers must be fewer than five years from their terminal degree, and their scope of research must be basic or clinical research disciplines in the fields of probiotics, prebiotics, synbiotics, postbiotics or fermented foods. In addition, the researchers were required to show evidence of a significant research finding and its publication(s), new ideas that advance the field, and / or evidence of impact through citizenship, general outreach, social media or other means.

The prize committee chose the two recipients from among dozens of applicants and identified each of them as having made important contributions to the field at this early stage in their scientific careers. Each winner will receive a cash prize and an opportunity to speak at the ISAPP annual meeting, to be held in Spain in June, 2022.

Stay tuned to learn more about these rising star researchers!

See here for details about the 2022 Glenn Gibson Early Career Research Prize

Do fermented foods contain probiotics?

/in Consumer Blog, ISAPP Science Blog /by KC

By Prof. Maria Marco, PhD, Department of Food Science & Technology, University of California, Davis

We frequently hear that “fermented foods are rich in beneficial probiotics.” But is this actually true? Do fermented foods contain probiotics?

The quick answer to this question is no – fermented foods are generally not sources of probiotics. Despite the popular assertion to the contrary, very few fermented foods contain microbes that fit the criteria to be called probiotic. But this fact does not mean that fermented foods are bad for you. To uphold the intent of the word probiotic and to explain how fermented foods actually are healthy, we need to find better ways to describe the benefits of fermented foods.

Probiotics are living microorganisms, that when administered in adequate amounts, confer a health benefit on the host (Hill et al 2014 Nat Rev Gastroenterol Hepatol). This current definition reflects minor updates to a definition offered by an expert consultation of scientists in 2001 convened by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization. Evident from the definition, a microbial strain is not a probiotic unless a health benefit has been found with its use. At a minimum, the strain should be proven to be beneficial in at least one randomized controlled trial (RCT). Probiotics must also be defined at the strain level through genome sequencing (a strain is a single genotype of a species).

Fermented foods, on the other hand, have no requirement to improve health. Fermented foods are foods and beverages made through desired microbial growth and enzymatic conversion of food components. This definition was recently formulated by an ISAPP consensus panel of scientific experts to affirm the common properties of all foods of this type and to differentiate foods that may look or taste similar but are not made using microbes (Marco et al 2021 Nat Rev Gastroenterol Hepatol). Fermented foods encompass an expansive variety of foods made from animal and plant sourced ingredients and produced from all types of microbial metabolism. The desired characteristics of these foods are frequently how they look, smell, and taste. There no expectation in this definition that fermented foods alter health in any way.

There is also no requirement for fermented foods contain living microbes at the time they are ingested. Foods such as bread, chocolate, and beer are fermented but then are baked, roasted, and/or filtered. This means those fermented foods cannot be probiotic.

Some fermented foods, such as kimchi and kombucha, are typically eaten with living microbes present. However, the microbes in those foods usually do not meet the criteria to be called probiotic. Whether the fermented food was made at home or purchased from the supermarket, studies investigating whether the microbes in those fermented foods are specifically responsible for a health benefit remain to be done. Those foods also do not contain microbes defined to the strain level, nor is the number of living microbes typically known. An exception to this is if specific strains previously shown to provide a health benefit in one or more RCT are intentionally used in the production of the food and remain viable at expected numbers over the shelf-life of that fermented food product. An example of this would be a commercial fermented yogurt that has an added probiotic strain remaining viable at the time of consumption, beyond the strains that carried out the fermentation.

Despite these distinctions between probiotics an fermented foods, the probiotics term has pervaded common lexicon to mean “beneficial microbes”. In contrast to pathogenic or harmful microbes, beneficial microbes are those that are understood to help rather than hurt bodily functions. However, just as we do not assume that all pathogens cause the same disease or result in the same severity of symptoms, we should also not expect that beneficial microbes all serve the same purpose. By analogy, automobiles are useful vehicles which help us to get from place to place. We do not expect that all automobiles perform like those used for Formula 1 racing. Microbes are needed to make fermented foods and may be beneficial for us, but we should not assume that those drive health benefits like established probiotic strains.

What are the consequences of calling fermented foods probiotic when they include undefined numbers of living microbes for which strain identities are not known? One can suppose that there is no harm in labeling or describing those products as “probiotic” or “containing probiotics”. However, by doing so, confusion and misunderstanding is created and too often, spread by journalists, nutritionists, scientists, and medical professionals. For example, news articles in reputable sources have written that foods like kefir, kimchi, sauerkraut made from beets or cabbage, pickles, cottage cheese, olives, bread and chocolate are rich in probiotics. As misuse perpetuates, what becomes of bona fide probiotics shown with rigorous study to benefit health, such as reducing the incidence and duration of diarrhea or respiratory infections? It becomes difficult to know which strains have scientific proof of benefit. Just as there are laws for standards of food identity, we should strive to do the same when describing microbes in fermented foods.

Avoiding the term probiotic when describing fermented foods should not stop us from espousing the myriad of positive attributes of those foods. Besides their favorable sensory qualities, fermented foods are frequently safer and better tolerated in the digestive tract than the foods they are made from. During the production of fermented foods, microbes remove or reduce toxins in the ingredients and produce bioactive compounds that persist long after the microbes that make them are gone.

Even though the living microbes in fermented foods may not rise to the standard of a probiotic, they may provide health benefits. We just don’t have the studies to prove that they do. With more study, we may find that viable microbes in fermented foods work similarly to probiotics in the digestive tract through shared mechanisms. This is already known for yogurts. Yogurt cultures share the ability to deliver lactase to the intestine, thereby improving tolerance of lactose by intolerant individuals. Clinical and epidemiological studies performed on fermented foods already suggest an association between them and different health benefits but as we recently explained (Marco et al 2021 J Nutrition), more work is needed in order to understand if and what benefits these microbes provide.

For now, we should simply continue enjoying the making and eating of fermented foods and reserve the term probiotics for those specific microbial strains which have been shown to improve our health. Marketers should resist labeling products as containing probiotics if their products do not meet the criteria for a probiotic. Indeed, the descriptor “live and active cultures” more accurately reflects the microbial composition of many fermented foods, and should be used until controlled human trials demonstrating health benefits are conducted.

 

Additional resources:

How are probiotic foods and fermented foods different? ISAPP infographic.

Fermented foods. ISAPP infographic.

What are fermented foods? ISAPP video.

Are fermented foods probiotics? Webinar by Mary Ellen Sanders, PhD.

 

ISAPP’s 2021 year in review

/in ISAPP Science Blog /by KC

By Mary Ellen Sanders, PhD, ISAPP Executive Science Officer

The upcoming year-end naturally leads us to reflect about what has transpired over the past 12 months. From my perspective working with ISAPP, I witnessed ISAPP board members and the broader ISAPP community working creatively and diligently to find solutions to scientific challenges in probiotics, prebiotics and related fields. Let’s look back together at some of the key developments of 2021.

ISAPP published outcomes from two consensus panels this year, one on fermented foods and one on postbiotics. The popularity of these articles astounds me, with 49K and 29K accesses respectively, as of this writing. I think this reflects recognition on the part of the scientific community of the value – for all stakeholders – of concise, well-considered scientific definitions of terms that we deal with on a daily basis. If we can all agree on what we mean when we use a term, confusion is abated and progress is facilitated. The postbiotics definition was greeted with some resistance, however, and it will remain to be seen how this is resolved. But I think ISAPP’s response about this objection makes it clear that productive definitions are difficult to generate. Even if the field ultimately embraces another definition, it is heartening to engage in scientific debate about ideas and try to find alignment.

Keeping with the idea of postbiotics, a noteworthy development this year was the opinion from the European Food Safety Authority that the postbiotic made from heat-treated Akkermansia muciniphila is safe for use as a novel food in the EU. Undoubtedly, this development is a bellwether for likely future developments in this emerging area as some technological advantages to postbiotics will make these substances an attractive alternative to probiotics IF the scientific evidence for health benefits becomes available.

Recognizing the existing need for translational information for clinicians, ISAPP developed a continuing education course for dietitians. Published in March, it has currently reached close to 6000 dietitians. This course focused on probiotics, prebiotics and fermented foods: what they and how they might be applied in dietetic practice. It is a freely available, self-study course and completion provides two continuing education credits for dietitians.

On a sad note, in March of this year, ISAPP suffered the loss of Prof. Todd Klaenhammer. Todd was a founding ISAPP board member, and directed many of our activities over the course of his 18-year term on the board. He was also my dear friend and major advisor for my graduate degrees at NC State many years ago.  As one former collaborator put it, “I was not prepared to finish enjoying his friendship and mentorship.” See here for a tribute to Prof. Klaenhammer on the ISAPP blog: In Memoriam: Todd Klaenhammer.

So where will 2022 lead ISAPP? The organization has now published five consensus definitions: probiotics, prebiotics, synbiotics, postbiotics and fermented foods – extending its purview beyond where it started, with probiotics and prebiotics. Through the year ahead, ISAPP is committed to providing science-based information on the whole ‘biotics’ family of substances as well as fermented foods. Our Students and Fellows Association is growing, supported by the opportunity for young scientists to compete for the Glenn Gibson Early Career Researcher Prize. We continue to see our industry membership expand. Through our new Instagram account and other online platforms, our overall community is increasing. The ISAPP board of directors continues to evolve as well, with several long-term members leaving the board to make room for younger leaders in the field who will direct the future of the organization. This applies to me as well, as I have made the difficult decision to depart ISAPP in June of 2023. Thus, hiring a new executive director/executive science officer is an important priority for ISAPP in 2022. My 20 years with ISAPP have seen the organization evolve tremendously, through the hard work of incredible board members as well as many external contributors. We will strive to make 2022 – our 20th anniversary – ISAPP’s best year yet.

Scientists looking at a bottle of probiotic supplements.

Current issues in probiotic quality: An update for industry

/in ISAPP Science Blog /by KC

By Dr. Mary Ellen Sanders, ISAPP, Dr. Kit Goldman, USP, Dr. Amy Roe, P&G, Dr. Christina Vegge, Dr. Jean Schoeni, Eurofins

With probiotic dietary supplement use growing globally and an increasing array of products on the market, probiotic quality is an issue of perpetual relevance to industry. Best practices for producing high-quality probiotics change frequently, making it important for companies to stay informed.

ISAPP convened a webinar on this topic, available to ISAPP members only. The webinar took place November 16, 2021, and was hosted by Executive Science Officer, Dr. Mary Ellen Sanders. Speakers focused on the activities of the United States Pharmacopoeia (USP), a non-profit organization based in the US and operating globally, which for the past 200 years has worked to improve public health through development of quality standards for medicines, dietary supplements and foods. In 2017 USP formed an Expert Panel on probiotics.

Dr. Kit Goldman, Sr Director, Dietary Supplements and Herbal Medicines, USP, spoke about the origin of USP and the USP activities related to probiotic quality. USPs expert volunteers have determined the necessary parameters for probiotic quality standards, which include tests for identification, assay/enumeration and contaminants, and have created standards for a number of probiotic species/strains. In the course of doing so, the Probiotics Expert Panel identified specific areas where more information was needed to fully understand issues related to probiotic quality. This led to the formation of sub-teams to consider aspects of probiotic identification, enumeration and safety.

Dr. Amy Roe, Principal Scientist at P&G, spoke on appropriate regulatory requirements for probiotic safety. Currently, there is no global harmonization on the requirements for establishing probiotic safety for use in foods and supplements. Although ‘history of safe use’ has been central to safety assessments for many current probiotic species, probiotic manufacturers are increasingly seeking to use new strains, species, and next-generation probiotics; justification of safety based on a significant history of use may be challenged. USP and other stakeholders are looking to develop best practices guidelines for assessing the quality and safety of probiotics. A current initiative of the USP seeks to provide expert advice specific to safety considerations for probiotics through reviewing global regulatory guidelines, evaluating appropriateness of traditional animal toxicology studies for studying the safety of probiotics, highlighting the importance of proper manufacturing practices with regard to final product safety, and outlining of essential parameters of a comprehensive safety assessment for a probiotic.

Dr. Jean Schoeni, Fellow at Eurofins, spoke on comparing probiotic enumeration methods. One challenge faced by the USP Probiotics Expert Panel is how to compare the increasing number of probiotic enumeration methods appearing in monograph submissions. A sub-team of the panel developed a solution that combines APLM (Analytical Procedures Lifecycle Management – a streamlined approach for determining the method’s fitness for intended use) with TI (tolerance interval) calculations. Schoeni encouraged companies to adopt this solution, highlighting tools that have been provided to the probiotics industry through publication of the sub-team’s work.

Dr. Christina Vegge spoke on quantification of multi-strain blends. For probiotic products comprising multiple strains, the viable numbers of each strain in these products would ideally be quantified. However, reliance on plate count methods creates analytical challenges regardless of whether the quantification of viable numbers of each strain in the blend is conducted prior to or after blending. Further challenges arise when addressing the reductions in potency over shelf life of the product. For multi-strain products, plate count procedures are insufficient—and currently no official guideline or general best practice exists to resolve this situation. Therefore, the USP Probiotics Expert Panel wants to conduct an explorative study to examine non-culture based technologies to quantify the viable composition of multi-strain blends.

A recording of this webinar is available for ISAPP industry members only. Please see here and email info@nullisappscience.org for the password to access this page.

Publications (open access) from USP Probiotics Expert Panel:

Jackson et al. Improving End-User Trust in the Quality of Commercial Probiotic Products. Front Microbiol. 2019 Apr 17;10:739.  doi: 10.3389/fmicb.2019.00739.

Weitzel MLJ, et al. Improving and Comparing Probiotic Plate Count Methods by Analytical Procedure Lifecycle Management. Front Microbiol. 2021 Jul 12;12: 693066. doi: 10.3389/fmicb.2021.693066.

 

 

The American College of Gastroenterology recommends against use of probiotics for primary or secondary prevention of C. difficile

/in Uncategorized /by KC

By Prof. Daniel Merenstein MD, Georgetown University School of Medicine and Prof. Eamonn Quigley MD FRCP FACP MACG FRCPI,  Houston Methodist Hospital and Weill Cornell Medical College

The American College of Gastroenterology (ACG) recently published ACG Clinical Guidelines: Prevention, Diagnosis, and Treatment of Clostridioides difficile Infections. This review considers probiotics for prevention of CDI. The ACG’s recommendations regarding probiotics and C. difficile infection (CDI) are:

  1. We recommend against probiotics for the prevention of CDI in patients being treated with antibiotics (primary prevention) (conditional recommendation, moderate quality of evidence).
  2. We recommend against probiotics for the prevention of CDI recurrence (secondary prevention) (strong recommendation, very low quality of evidence).

The ACG guidelines take a different approach to the evidence relating to probiotics than that of the American Gastroenterological Association (AGA) or the Cochrane Collaboration. The most recent Cochrane review on prevention of C. difficile-associated diarrhea (CDAD) concluded in brief, “moderate certainty evidence suggests that probiotics are effective for preventing CDAD”. In the AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders, the recommendation was:

In adults and children on antibiotic treatment, we suggest the use of S. boulardii; or the 2-strain combination of L. acidophilus CL1285 and Lactobacillus casei LBC80R; or the 3-strain combination of L acidophilus, Lactobacillus delbrueckii subsp bulgaricus, and Bifidobacterium bifidum; or the 4-strain combination of L. acidophilus, L. delbrueckii subsp bulgaricus, B. bifidum, and Streptococcus salivarius subsp thermophilus over no or other probiotics for prevention of C difficile infection. (Conditional recommendation, low quality of evidence.)

In both the AGA and ACG guidelines the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used. How, then, did they come to such different conclusions and recommendations?

The ACG guideline stated,  “a meta-analysis of 19 RCTs that concluded that probiotics were helpful at prevention of CDI in hospitalized patients if given close to start of antibiotics, with a 70% lower risk if probiotics were started within 2 days but falling to a 30% risk reduction if probiotics were started after 2 days of antibiotic therapy”. But then they did not take timing of probiotic administration into account as they assessed the evidence. Instead, they use the negative PLACIDE trial to override all other evidence for primary prevention. The PLACIDE trial was a well-done trial, but participants started their probiotic treatment 3- 7 days after antibiotics. Thus, it would seem that the ACG guideline’s conclusion could favor probiotics as long as they can be started within 2 days of the antibiotic and not recommend against probiotic use.

The ACG guideline objects to combining data on different probiotic strains in meta-analyses in order to provide evidence in favor of probiotics: “Evidence to support probiotics for this indication comes mainly from meta-analyses that pool data from small trials of different probiotic formulations and methodologies.” This is true, but the Cochrane review found thirty-nine studies (8,672 participants) that met their eligibility criteria and it is noteworthy that several different probiotics were found to be effective. The Cochrane number needed to treat (NNT) to prevent CDI is 42. However, if the ACG thought this was driven by too many negative trials, they could have qualified their recommendation. The Cochrane review found in subgroup analyses that probiotics are most effective (NNT=12) among trials with a CDI baseline risk >5%. But to conclude there is no benefit of probiotics for primary CDI is not supported by the evidence.

It is puzzling that ACG insists that the probiotic literature be pooled in a strain-specific manner, yet they support conclusions on fecal microbial transplant (FMT) even though FMT interventions are much more heterogeneous than probiotics in regard to composition and mode of administration. They recommend FMT for treatment of C. difficile based on only three double-blinded randomized clinical trials (here, here and here), only one of which was positive. The positive FMT study was conducted at two sites and compared donor stool (heterologous) versus patient’s own stool (autologous) administered by colonoscopy. Overall, 91% of patients in the FMT group achieved clinical cure compared with 63% in the control group. At site #1, the cure rate with donor FMT was 90.0% (CI, 51.8% to 98.7%) versus 42.9% with autologous FMT, whereas in site #2 the cure rate was essentially identical between the two groups. At site #2, donor FMT cure rate was 91.7% (CI, 57.2% to 98.9%) compared with 90.0% (CI, 51.8% to 98.7%) after autologous FMT. We mention this to question the consistency of evidence standards that the ACG guideline authors impose. They admonish pooled data from small trials of different probiotic formulations and methodologies yet ignore heterogeneity in FMT interventions. The data reviewed for probiotics was primarily from double-blinded randomized trials, while for FMT they rely on case series, uncontrolled studies or retrospective studies.

The authors go on to state, “… high quality evidence to support probiotics for most conditions is scarce.” How do they define “scarce” and “most conditions”? As mentioned, Cochrane found thirty-nine studies (8,672 participants) for prevention of CDAD. Under “summary of evidence”, the authors address issues such as size of the market, regulatory oversight, product cost and quality control problems with commercial products, all of which may reflect practical concerns with some probiotic products in the marketplace, but have nothing to do with available evidence. Furthermore, it is the only intervention where the financial value of the industry and cost of interventions is mentioned. Why are the size of the market or costs for FMT or drugs not just as relevant to this review? Cost is discussed throughout the recommendation but without performing or citing a formal cost analysis or cost-effectiveness analysis, even though there are approaches for doing so to inform evidence-based decision-making (here).

The authors indict probiotics for concerns about safety, citing not the thorough review sponsored by AHRQ and conducted by the RAND corporation that looked at 622 studies and found no statistically significant increased relative risk of the overall number of experienced adverse events (RR 1.00; 95% confidence interval [CI]: 0.93, 1.07, p=0.999), but by referring to a review article that cites case reports of blood infections and refers to one study with microbiota, not clinical, endpoints done in Israel on one commercial product. The data actually show that for well characterized, clinically tested probiotics with high levels of quality control the evidence for infectious complications in non-vulnerable populations is virtually nil. ACG does not mention that FMT was shut down due to safety concerns as soon as the pandemic started.

In summary, we are not convinced that the authors have justified their recommendation against the use of probiotics in relation to CDI prevention. They fail to clarify why the results of their GRADE evaluation of probiotic evidence for prevention of C. difficile resulted in totally different conclusions compared to the AGA document, which found evidence sufficient for conditional recommendation of four probiotic preparations. Further,  the review of evidence for probiotics, whether in terms of efficacy or safety, should be addressed in a manner consistent with other interventions considered and editorializing on issues such as market size, profits and product cost, in the absence of an objective approach using appropriate instruments, should be avoided.

The USDA Global Branded Food Products Database is Now Accepting Data on Live Microbes – Call for Data Submission

/in ISAPP Science Blog /by KC

Marie E. Latulippe, MS, RDN, Director of Science Programs and Brienna Larrick, PhD, PMP Scientific Program Manager, Institute for the Advancement of Food and Nutrition Sciences (IAFNS), Washington DC

As noted by Marco et al. (2020), evidence from observational studies and randomized controlled trials suggests that the consumption of safe, live microbes can support health. However, more data are needed to accept or refute this hypothesis, and to develop a full understanding of population exposure. As of October 2021, the USDA Global Branded Food Products Database is accepting information on live microbes in foods and beverages. With participation from manufacturers, this initiative will eventually enhance our understanding of the numbers of live microbes that populations consume from food.

The USDA Global Branded Food Products Database contains ingredient and nutrition composition data on over 368,000 branded and private label (i.e., store brand) foods and beverages. This information is provided voluntarily by the food industry. The impact of industry providing these data is substantial; it means these data are available to inform agricultural and food policy decisions by federal agencies, and to support research and regulatory queries by the public and private sectors. By supplying information on live microbes in foods, the food industry can provide researchers with useful data on quantities of live microbes in foods and enable them to link these data to associated health outcomes. Ultimately, this could contribute to determining if a recommended intake level for the consumption of safe, live microbes from foods (e.g., yogurts) is supported by evidence.

The food industry is encouraged to contribute to this initiative by providing the following data on the food and beverage products they produce:

  • Quantity (range) of live microbes
  • Method of analysis used to determine quantity of live microbes
  • Type(s) of live microbes present in the product

Data on live microbes can be submitted via 1WorldSync, a Global Data Synchronization Network (GDSN) data pool provider. For more information, including guidance for submitting data and technical support, visit here.

The partners in this public-private partnership are USDA, IAFNS, GS1 US, 1WorldSync, NielsenIQ Label Insight, and the University of Maryland. For more information on the USDA Global Branded Food Products Database, visit here.

ISAPP and IAFNS collaborate on a project focused on live dietary microbes through the IAFNS gut microbiome committee. Mary Ellen Sanders, Executive Science Officer for ISAPP, represents ISAPP on this committee.

Related links:

New ISAPP-led paper calls for investigation of evidence for links between live dietary microbes and health

Gut Microbiome Webinar Series sponsored by IAFNS

 

Should the concept of postbiotics make us see probiotics from a new perspective?

/in ISAPP Science Blog, Uncategorized /by KC

By Dr. Gabriel Vinderola, PhD,  Associate Professor of Microbiology at the Faculty of Chemical Engineering from the National University of Litoral and Principal Researcher from CONICET at Dairy Products Institute (CONICET-UNL), Santa Fe, Argentina

In early May 2021 an ISAPP consensus panel  defined postbiotics as “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host“. The fact that non-viable microbes may still deliver health benefits is not new for the scientific community and was reviewed more than 20 years ago. More recent studies demonstrating health effects of non-viable microbes spurred interest in this topic, leading ISAPP to carefully consider the emerging use of the term ‘postbiotic’ and provide a clear, modern, concise definition.

Postbiotics can be contrasted with probiotics: live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. In practice, probiotics  have likely always coexisted with inanimate microbes, as live microbes will die at all phases of production of a product. In the past, it seems the presence of inanimate microbes as part of probiotic products was not really considered. We all knew they were there, but made a default assumption that they had limited significance. As we consider postbiotics, though, we should perhaps look again at how to address the inanimate components of probiotic products.

The presence of inanimate cells in probiotic preparations: from lab to product

A loop of a fresh, overnight, live culture of a probiotic strain may still contain non-viable cells (Fig. 1). During the biomass production of a probiotic culture, an abundance of live cells can be observed in the exponential growth phase, but as the culture enters the stationary phase, a significant increase in the proportion of non-viable cells occurs (Fig. 2). Yet the culture may display a satisfactory high number of viable cells as verified by traditional plating on agar media. Some years ago, it was reported that a fresh culture of a lactobacilli strain may display a live/dead cells ratio of ca. 100/1. However, this ratio may change to 1:1 after freeze-drying, as studied using flow cytometry, a technology that allows the quantification of both live and dead cells in a culture-independent way. Therefore, a recently freeze-dried culture of a probiotic strain may contain 1010 log CFU/g of live cells, but also the same amount of non-viable cells.

Food supplements may have a shelf life between 12 and 24 months at room temperature and over this time, a proportion of cells will likely lose viability along the shelf life. This depends on the intrinsic resistance of the strain, the nature of the matrix used for freeze-drying, the water activity remaining after lyophilization, the package and the storage conditions. Taking this into consideration, the probiotic supplements industry overfills probiotic capsules or sachets with 1.5 to 4 times more live cells, in order to warrant the delivery at the end of shelf life of the minimum amount of live cells to be able to deliver the expected health benefit. Considering that both freeze-drying and long-term storage may significantly increase the proportion of inanimate microorganisms in a probiotic supplement, a probiotic supplement could easily consist of more inanimate microorganisms than live ones. Yet if the products delivers the minimum amount of live cells to confer a health benefit, this makes the product fit the definition of probiotics so it must be considered a probiotic product. The probiotic focus has been prevalent during previous clinical trials and also during the shelf life of a probiotic product. Maybe we were just overlooking what was going on beyond the information obtained by CFU. These new insights do not change the status of a probiotic, but with due attention given to postbiotic components, offers the possibility to have better and better characterized products in the future.

Figure 1, above – Fluorescence microscopy images of an overnight (18h) culture of bifidobacteria (left) and lactobacilli (right) showing live (green) and non-viable cells (red). The Live/dead BackLight Invitrogen® kit was used for staining cells.

Figure 2, above – Fluorescence microscopy images of a culture of lactobacilli in the exponential (left) and late stationary (right) growth phase showing live (green) and non-viable cells (red). The Live/dead BackLight Invitrogen® kit was used for staining cells.

Are dead probiotics ‘postbiotics’?

What is the contribution of these inanimate cells to the overall health benefit observed for the probiotic culture? In most cases, no evidence exists documenting health benefits of inanimate probiotics. But we may have reason to suspect it may be relevant. For example, a live culture of Bifidobacterium bifidum MIMBb75 significantly alleviated irritable bowel syndrome symptoms and improved quality of life in a double-blind, placebo-controlled study when delivered at 109 CFU, but also the same strain performed equally well for the same end-point when delivered as a heat-inactivated culture. Also, a novel next-generation probiotic strain of Akkermansia muciniphila performed equally well in its live and pasteurized form for improving several metabolic parameters in overweight and obese volunteers. In these cases, it can be said that both strains fit simultaneously the probiotic and the postbiotic definitions.

However, does this mean that as the strain gradually loses viability during storage it gradually becomes a postbiotic? No! This is because method of strain inactivation may play an important role in the health benefit observed. For example, the health benefit delivered by a strain that underwent a heat inactivation can not be assumed to have the same functionality if it is left to die on its own on the shelves. A heat treatment may, for instance, modifiy the spatial display of surface proteins and this may lead to a different immunomodulating capacity of the strain when compared to spontaneous and gradual cell viability lost along storage.

Characterizing probiotic products with an eye to the presence of non-viable cells

By definition, probiotics must be quantified. In the past, this quantification has been limited to numbers of viable cells, typically using a colony count method. This is wholly appropriate, as probiotics must be alive. Yet for the future, will it become necessary to quantify the numbers of non-viable microbial cells as well? With evidence emerging that these non-viable cells may be functional components, then a reasonable argument can be made that this component of a probiotic product should also be quantified. This has implications for characterizing products for use in intervention trials and for the marketplace. The challenge for the marketplace is that probiotic products should deliver the functionality observed in intervention trials.

Reports of trials typically indicate a viable count of the probiotic being tested, but these can be reported in different ways. For example, the statement may indicate delivery of 1.9 × 107 CFU/day of the strain XXX, or delivery of > 1.9 × 107 CFU/day of the strain XXX. These are very different and neither gives any indication of the level of non-viable microbes. The first expression is a specific measure of the viable count at a particular point in time. The second indicates a target minimum and the actual count of viable cells could be much greater. Counts all along the intervention are rarely reported, even though that count could change substantively over time. Papers rarely report if the same batch or different batches of the probiotic preparation were used. The potentially increasing proportion of inanimate microbes is never reported.

In light of postbiotics, future studies should report quantifications of both live and inanimate microbes. Although it is not clear at this time what role inanimate microbes may play in probiotic efficacy, a first step is understanding the composition of probiotic products.

 

ISAPP members can access Dr. Vinderola’s webinar on this topic here. Email info@nullisappscience.org if you require the password.

Hands holding mobile phone

Virtual events continue to fill gaps as in-person meetings are being planned

/in News /by KC

Prof. Bob Hutkins, PhD, University of Nebraska – Lincoln, USA

For scientists, annual meetings provide coveted opportunities to hear about the latest scientific advances from expert researchers, and they are where students and trainees get to present their research, often for the first time. Of course, meeting and socializing with colleagues, both new and old, during breaks and evening sessions is also an important part of these conferences.

Yet over the past two years, most occasions to meet face-to-face were canceled. Virtual meetings became the new normal and, even though a poor substitute for in-person gatherings, provided opportunities to connect and share emerging science. As we anticipate being together again in person – hopefully for 2022 meetings – take note of three upcoming conferences to fill the gap. Each of these feature meetings are related to the gut microbiome, diet, and health.

(1) In October, the Agriculture and Health Summit: Cultivating Gut Health at the Crossroads of Food & Medicine is a FREE three-day virtual conference that brings together a unique combination of researchers, industry leaders and thought leaders from the biomedical and agricultural sectors for important conversations about the future of human health. The event will provide a rare opportunity for individuals with diverse areas of expertise to discuss opportunities and challenges in creating ‘foods for health’ through the gut microbiome, working toward solutions in nutrition and medicine. More information can be found here. Among the presenters are ISAPP Executive Science Officer, Mary Ellen Sanders, and board members, Dan Merenstein and Bob Hutkins.

 

(2) Then in November, a Nature-sponsored online conference called Reshaping the Microbiome through Nutrition will be held. According to the website, “this conference will bring together researchers working on the microbiome and nutrition to discuss how our microbiota use and transform dietary components, and how these nutrients and their products influence host health throughout life, including effects on development and infectious and chronic diseases. A central theme of the meeting will be how diet and dietary supplements could be harnessed to manipulate the microbiome with the aim of maintaining health and treating disease”. More information is found here.

(3) Another meeting in November is organized across ten centers/institutes at the NIH and the Office of Dietary Supplements and the Office of Nutrition Research. This two-day conference November 5 and 8, titled Precision Probiotic Therapies—Challenges and Opportunities, features a Keynote address by Prof. Jeff Gordon, from the Washington University School of Medicine. ISAPP president Prof. Dan Merenstein, Georgetown University School of Medicine, is also presenting. To register for this FREE meeting, see here.

 

In this current era, interest in how diet (including probiotics, prebiotics, and fermented foods) influences the microbiome and affects human and animal health has never been greater, as is evident by these and other similarly-themed conferences.

ISAPP is planning its next annual by-invitation meeting, to be held in person.

 

Using probiotics to support digestive health for dogs

/in ISAPP Science Blog /by KC

By Kelly S. Swanson, PhD, The Kraft Heinz Company Endowed Professor in Human Nutrition, University of Illinois at Urbana-Champaign, USA

Because dogs are considered to be members of the family by most pet owners today, their health and well-being is a top priority. As with humans, nutritional products supporting gastrointestinal health are some of the most popular. Many pets are healthy, but loose stools, constipation, and various gastrointestinal disorders and diseases such as inflammatory bowel disease and irritable bowel syndrome are common. In fact, within the pet food conversation, digestive health improvements have been the most discussed health benefits among social media discussion posts over the past 2 years (see here). Given the high interest in digestive health, it is not surprising that the canine microbiome has been of great interest over the past decade, with many recent reviews reporting on the overall composition of the gastrointestinal microbiota and how it is impacted by diet (Barko et al., 2018; Alessandri et al., 2020; Wernimont et al., 2020). Gastrointestinal microbiome changes contributing to or resulting from digestive diseases have also been documented in dogs (Redfern et al., 2017; Ziese and Suchodolski, 2021). Animals under high levels of stress or undergoing antibiotic therapy are also known to have poor stool quality and an altered gut microbiota (i.e., dysbiosis) (Pilla et al., 2020).

Dietary fibers and prebiotics are commonly used in complete and balanced diets to improve or maintain stool quality, provide laxation, and positively manipulate the microbiota of healthy animals. The use of probiotics is also popular in dogs, but the route of administration, efficacy, and reason for use is usually different than that of fiber and prebiotics. Probiotics are usually provided in the form of supplements (e.g., powders, capsules, pastes) and are most commonly used to treat animals with gastrointestinal disease rather than support the healthy condition. Live microbes are added to many dry extruded foods as ‘probiotics’, but in many cases, maintaining viability and evidence for a health benefit for dogs is lacking for these products. Such microbes would not meet the minimum criteria to be called a ‘probiotic.’ Viability is a challenge because most HACCP plans for producing complete and balanced pet foods include a kill step that inactivates all microorganisms. Therefore, inclusion must be applied post-extrusion on the outside of the kibble. Even if applied in this way, low numbers of viable organisms are common (Weese and Arroyo, 2003). Post-production inclusion is not possible for other diet formats (e.g., cans, pouches, trays). Although spore-forming bacteria that may survive the extrusion process have been of interest lately, evidence of efficacy is lacking thus far.

Picture of Simka (a Samoyed) courtesy of ISAPP board member Dr. Daniel Tancredi

Even though health benefits coming from the inclusion of live microorganisms in dog foods is not supported by the peer-reviewed literature, such evidence exists for many probiotic supplements. The clinical effects of probiotics in the prevention or treatment of gastrointestinal diseases in dogs have been reviewed recently (Schmitz and Suchodolski, 2016; Suchodolski and Jergens, 2016; Jensen and Bjornvad, 2018; Schmitz, 2021). Although some similarities exist, recent research has shown that distinct dysbiosis networks exist in dogs compared to humans (Vazquez-Baeza et al., 2016), justifying unique prevention and/or treatment strategies for dogs.

One population of dogs shown to benefit from probiotics has been those with acute idiopathic diarrhea and gastroenteritis, with a shorter time to resolution and reduced percentage of dogs requiring antibiotic administration being reported (Kelley et al., 2009; Herstad et al., 2010; Nixon et al., 2019). Probiotic administration has also been shown to benefit dogs undergoing antibiotic therapy and those engaged in endurance exercise – two conditions that alter the gastrointestinal microbiota and often lead to loose stools. In those studies, consumption of a probiotic helped to minimize gastrointestinal microbiome shifts and reduced the incidence and/or shortened the length of diarrhea (Gagne et al., 2013; Fenimore et al., 2017). Dogs diagnosed with inflammatory bowel disease have also been shown to benefit from probiotic consumption (Rossi et al., 2014; White et al., 2017). In these chronic conditions, drug therapy is almost always required, but probiotics have been shown to help normalize intestinal dysbiosis, increase tight junction protein expression, and reduce clinical and histological scores.

So what is the bottom line? Well, for dogs with a sensitive stomach and/or digestive health issues, probiotics may certainly help. Rather than relying on live microbes present in the dog’s food or adding a couple spoonfuls of yogurt to the food bowl each day, it is recommended that owners work with their veterinarian to identify a probiotic that has the best chance for success. The probiotic selected should provide an effective dose, be designed for dogs, target the specific condition in mind, and be backed by science. As summarized here, it is important to remember that all probiotics are different so the specific microorganism(s), supplement form, storage conditions, and dosage are all important details to consider.

 

Kelly Swanson joined the ISAPP board of directors in June, 2020, providing valuable expertise in animal gut health and overall health. Swanson also chaired the 2019 ISAPP-led international consensus panel on the definition of synbiotics.

ISAPP board member Prof. Dan Tancredi kindly provided pictures of Simka, pet Samoyed, for the post.

 

Bacterial vesicles: Emerging potential postbiotics

/in ISAPP Science Blog /by KC

By Dr. Gabriel Vinderola, PhD,  Associate Professor of Microbiology at the Faculty of Chemical Engineering from the National University of Litoral and Principal Researcher from CONICET at Dairy Products Institute (CONICET-UNL), Santa Fe, Argentina

The recently published ISAPP consensus paper defines a postbiotic as “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host“. Such a definition quickly brings to mind that a postbiotic is not equivalent to microbial metabolites. A postbiotic should also contain inanimate microbial cells or cell fragments. Metabolites or fermentation products may be present, but they are not required.

Because microbes are complex entities, we must be open to innovative understandings of what a postbiotic might entail. Indeed, although not explicitly mentioned in the ISAPP consensus paper, extracellular membrane vesicles may comprise an innovative conceptualization of a postbiotic, falling within the ‘cell component’ part of the postbiotic definition.

Bacterial vesicles

Extracellular membrane vesicles (EMV) are universal carriers of biological information produced in all domains of life. Bacterial EMV are small, spheroidal, membrane-derived proteoliposomal nanostructures, typically ranging from 25 – 250 nm in diameter, containing proteins, lipids, nucleic acids, metabolites, numerous surface molecules and many other biomolecules derived from their progenitor bacteria (Figure 1). Bacterial vesicles have been known for more than 50 years as structures able to carry cellular material (Ñahui Palomino et al. 2021).  However, studies on membrane vesicles derived from Gram-positive bacteria are more recent as it was for a time believed they were incapable of producing vesicles due to their thick and complex cell walls, and the lack of an outer membrane. Today, EMVs have been isolated from Gram-positive probiotic bacteria, including those belonging to the Lactobacillaceae family (under which Lactobacillus was recently split into many new genera) and the Bifidobacterium genus. In probiotic bacteria, vesicles may mediate quorum sensing and material exchange. Perhaps even more important, they can act as mediators of bacteria-to-cell and bacteria-to-bacteria interactions. As bacterial EMV are inanimate structures that cannot replicate, they fit the postbiotic definiton as cell components as long as other criteria stipulated by the definition are met.

Figure 1. Membrane vesicles budding on the surface of L. reuteri DSM 17938 and released into the surrounding medium. These vesicles were described in by Grande et al. 2017. Photo used with permission of BioGaia.

Functions of bacterial vesicles related to potential health benefits

Underlying mechanisms and corresponding molecules driving health effects of bacterial vesicles are not well understood, in part due to reliance on in vitro models. Bacterial EMV derived from Lactobacillaceae spp., Bifidobacterium spp., and Akkermansia spp. have been reported to alleviate metabolic syndrome and allergy symptoms, promote T-cell activation and IgA production, strengthen gut barrier function, and exhibit anti-viral and immunomodulatory properties (Kim et al. 2016; Tan et al. 2018; Ashrafian et al. 2019; Molina-Tijeras et al. 2019; Palomino et al. 2019; Shehata et al. 2019; Bäuerl et al. 2020). Interestingly, vesicles from Limosilactobacillus reuteri DSM 17938 (West et al. 2020) and Lacticaseibacillus casei BL23 (Domínguez Rubio et al. 2017) may accomplish some of the the effects of these probiotic bacteria. In fact it is not unreasonable to think that EMVs may be already present and active in probiotic products.

Challenges for bacterial vesicle production

To develop a postbiotic from microbial EMVs, many challenges need to be overcome.  Defining optimal cultivation conditions, and methods for vesicle release, isolation and scaling up are some of the challenges of bacterial vesicle production. There are several studies showing that altering the cultivation parameters can impact vesicle production. Examples of treatments shown to increase vesicle release include exposure to UV radiation and antibiotic pressure (Gamalier et al. 2017; Gill et al. 2019). Exposure to glycine has also been shown to increase vesicle production (Hirayama & Nakao 2020). Interventions during culture, for example by introducing agitation and varying pH, can possibly be ways to potentiate vesicle release and increase their bioactivity (Müller et al. 2021). A recent report also revealed that B. longum NCC2705 released a myriad of vesicles when cultured in human fecal fermentation broth, but not in basal GAM anaerobic medium (Figure 1). Moreover, the B. longum vesicle production pattern differed among individual fecal samples suggesting that metabolites derived from symbiotic microbiota stimulate the active production of vesicles in a different manner (Nishiyama et al. 2020). Whether any of these treatments and culture conditions are general or strain specific remains to be elucidated. Large differences in the number of vesicles that may be obtained by different extraction methods can occur (Tian et al. 2020). Tangential flow filtration or the use of antibodies targeting specific epitopes of the vesicles are some of the options proposed for the large scale isolation of EMV (Klimentová & Stulík 2015).

Figure 2. Left: Bifidobacterium longum NCC2705 grown on GAM broth. Right: secretion of membrane vesicles by Bifidobacterium longum NCC2705: the strain was cultured in bacterial-free human fecal fermentation broth and secreted a myriad of membrane vesicles. Reported and adapted from Nishiyama et al. 2020.

Progress has been made on the production of bacterial vesicles in recent years, yet several issues remain to be clarified including how vesicles are generated from the progenitor microbe, how the composition of vesicles changes according to the culture conditions, how to target specific bacterial vesicle purification from a pool of vesicles derived from other organisms (for example, bacterial vesicles produced in milky media can be accompanied by vesicles from eukaryotic cells present in the milk), safety aspects, quantification methods and the regulation of their use by the corresponding authority.

Their future as potential postbiotics

Membrane vesicles are an exciting opportunity for the development of postbiotics. A potential benefit of vesicles is that their small size compared to whole cells may enable them to more readily migrate to host tissues that could not be otherwise reached by a whole cell (Kulp & Kuehn 2010). Their nanostructure enables them to penetrate through the gut barrier and to be delivered to previously unreachable sites through the bloodstream or lymphatic vessels, and to interact with different cell types (Jones et al. 2020). For example, bacterial rRNA and rDNA found in the bloodstream and the brain of Alzheimer’s patients were postulated to have originated from bacteria vesicles (Park et al. 2017). Safety of EMVs must be carefully considered and assessed, even if they are derived from microbes generally recognized as safe, as their small size may increase penetration capacity with potential and yet unknown systemic effects. Novel postbiotics derived from microbial membrane vesicles is an intriguing area for future research to better understand production parameters, safety and functionality.

Thanks to Cheng Chung Yong, postdoctoral researcher at Morinaga Milk Industry Co., LTD (Japan) and Ludwig Lundqvist, industrial PhD student at BioGaia AB (Sweden) for their contributions to this blog, and Mary Ellen Sanders and Sarah Lebeer from ISAPP for fruitful discussions.

References

Ashrafian, F., Shahriary, A., Behrouzi, A., Moradi, H.R., Keshavarz Azizi Raftar, S., Lari, A., Hadifar, S., Yaghoubfar, R., Ahmadi Badi, S., Khatami, S. and Vaziri, F., 2019. Akkermansia muciniphila-derived extracellular vesicles as a mucosal delivery vector for amelioration of obesity in mice. Frontiers in microbiology, 10, p.2155.

Bäuerl, C., Coll-Marqués, J.M., Tarazona-González, C. and Pérez-Martínez, G., 2020. Lactobacillus casei extracellular vesicles stimulate EGFR pathway likely due to the presence of proteins P40 and P75 bound to their surface. Scientific reports, 10(1), pp.1-12.

Domínguez Rubio, A.P., Martínez, J.H., Martínez Casillas, D.C., Coluccio Leskow, F., Piuri, M. and Pérez, O.E., 2017. Lactobacillus casei BL23 produces microvesicles carrying proteins that have been associated with its probiotic effect. Frontiers in microbiology, 8, p.1783.

Gamalier, J.P., Silva, T.P., Zarantonello, V., Dias, F.F. and Melo, R.C., 2017. Increased production of outer membrane vesicles by cultured freshwater bacteria in response to ultraviolet radiation. Microbiological research, 194, pp.38-46.

Grande, R., Celia, C., Mincione, G., Stringaro, A., Di Marzio, L., Colone, M., Di Marcantonio, M.C., Savino, L., Puca, V., Santoliquido, R. and Locatelli, M., 2017. Detection and physicochemical characterization of membrane vesicles (MVs) of Lactobacillus reuteri DSM 17938. Frontiers in microbiology, 8, p.1040.

Gill, S., Catchpole, R. & Forterre, P., 2019. Extracellular membrane vesicles in the three domains of life and beyond. FEMS microbiology reviews, 43(3), pp.273–303.

Hirayama, S. & Nakao, R., 2020. Glycine significantly enhances bacterial membrane vesicle production: a powerful approach for isolation of LPS-reduced membrane vesicles of probiotic Escherichia coli. Microbial biotechnology, 13(4), pp.1162–1178.

Jones, E.J., Booth, C., Fonseca, S., Parker, A., Cross, K., Miquel-Clopés, A., Hautefort, I., Mayer, U., Wileman, T., Stentz, R. and Carding, S.R., 2020. The uptake, trafficking, and biodistribution of Bacteroides thetaiotaomicron generated outer membrane vesicles. Frontiers in microbiology, 11, p.57.

Kim, J.H., Jeun, E.J., Hong, C.P., Kim, S.H., Jang, M.S., Lee, E.J., Moon, S.J., Yun, C.H., Im, S.H., Jeong, S.G. and Park, B.Y., 2016. Extracellular vesicle–derived protein from Bifidobacterium longum alleviates food allergy through mast cell suppression. Journal of Allergy and Clinical Immunology, 137(2), pp.507-516.

Kulp, A. & Kuehn, M.J., 2010. Biological functions and biogenesis of secreted bacterial outer membrane vesicles. Annual review of microbiology, 64, pp.163–184.

Molina-Tijeras, J.A., Gálvez, J. & Rodríguez-Cabezas, M.E., 2019. The immunomodulatory properties of extracellular vesicles derived from probiotics: a novel approach for the management of gastrointestinal diseases. Nutrients, 11(5), p.1038.

Müller, L., Kuhn, T., Koch, M. and Fuhrmann, G., 2021. Stimulation of probiotic bacteria induces release of membrane vesicles with augmented anti-inflammatory activity. ACS Applied Bio Materials, 4(5), pp.3739-3748.

Ñahui Palomino, R.A., Vanpouille, C., Costantini, P.E. and Margolis, L., 2021. Microbiota–host communications: Bacterial extracellular vesicles as a common language. PLoS Pathogens, 17(5), p.e1009508.

Nishiyama, K., Takaki, T., Sugiyama, M., Fukuda, I., Aiso, M., Mukai, T., Odamaki, T., Xiao, J. Z., Osawa, R., & Okada, N. 2020. Extracellular vesicles produced by Bifidobacterium longum export mucin-binding proteins. Applied and Environmental Microbiology, 86(19), e01464-20.

Palomino, R.A.Ñ., Vanpouille, C., Laghi, L., Parolin, C., Melikov, K., Backlund, P., Vitali, B. and Margolis, L., 2019. Extracellular vesicles from symbiotic vaginal lactobacilli inhibit HIV-1 infection of human tissues. Nature communications, 10(1), pp.1-14.

Park, J.Y., Choi, J., Lee, Y., Lee, J.E., Lee, E.H., Kwon, H.J., Yang, J., Jeong, B.R., Kim, Y.K. and Han, P.L., 2017. Metagenome analysis of bodily microbiota in a mouse model of Alzheimer disease using bacteria-derived membrane vesicles in blood. Experimental neurobiology, 26(6), p.369.

Shehata, M.M., Mostafa, A., Teubner, L., Mahmoud, S.H., Kandeil, A., Elshesheny, R., Boubak, T.A., Frantz, R., Pietra, L.L., Pleschka, S. and Osman, A., 2019. Bacterial outer membrane vesicles (omvs)-based dual vaccine for influenza a h1n1 virus and mers-cov. Vaccines, 7(2), p.46.

Tan, K., Li, R., Huang, X. and Liu, Q., 2018. Outer membrane vesicles: current status and future direction of these novel vaccine adjuvants. Frontiers in microbiology, 9, p.783.

Tian, Y., Gong, M., Hu, Y., Liu, H., Zhang, W., Zhang, M., Hu, X., Aubert, D., Zhu, S., Wu, L. and Yan, X., 2020. Quality and efficiency assessment of six extracellular vesicle isolation methods by nano-flow cytometry. Journal of extracellular vesicles, 9(1), p.1697028.

West, C.L., Stanisz, A.M., Mao, Y.K., Champagne-Jorgensen, K., Bienenstock, J. and Kunze, W.A., 2020. Microvesicles from Lactobacillus reuteri (DSM-17938) completely reproduce modulation of gut motility by bacteria in mice. PloS one, 15(1

Can dietary supplements be used safely and reliably in vulnerable populations?

/in ISAPP Science Blog /by KC

By Dr. Greg Leyer, Sr. Director – Scientific Affairs, Chr. Hansen, Inc., Madison, WI and Prof. Dan Merenstein, Department of Family Medicine, Georgetown University Medical Center, Washington DC

What is it that doctors look for when recommending or prescribing therapies to patients? If it is a drug, a supplement, a new diet, or even a new exercise regimen, they look for safety and efficacy. There are of course other things to consider, including cost, ease of administration, and patient compliance, among others. But safety and efficacy are their foremost concerns.

A recently published clinical report from the American Academy of Pediatrics (AAP) (Poindexter 2021) examined the evidence for probiotics to prevent morbidity and mortality in preterm infants. They concluded that probiotics could not be recommended. This differs from conclusions of the American Gastroenterological Association (AGA) (Su et al. 2020), which recommended specific probiotic strains for preterm (less than 37 weeks gestational age) and low birth weight infants. The AAP report also differs from the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) (Van den Akker et al. 2020), which recommends specific strains for this use, although their recommendations are not fully aligned with AGA’s (see What’s a Clinician to do When the Probiotic Recommendations from Medical Organizations Do Not Agree?).

The AAP report does a thorough job of reviewing data on use of probiotics in the NICU, including conflicting studies, lack of confirmatory studies of efficacious strains, and safety and cross contamination inside the NICU. However, the overriding theme of the report is “clinicians must be aware of the lack of regulatory standards for commercially available probiotic preparations manufactured as dietary supplements and the potential for contamination with pathogenic species.” Therefore, at the heart of the AAP failure to recommend probiotics is the concern that the quality of available products is insufficient. Because of the absence of a pharmaceutical-grade probiotic product for use in the United States, they posit, they cannot recommend usage. It is noteworthy that the trials performed on premature infants resulting in multiple conclusions of safety and efficacy have thus far utilized probiotic products manufactured as dietary supplements.

Probiotics can be marketed as drugs if they follow that regulatory pathway, but generally in the US they are sold under the regulatory classification of dietary supplements. Is the AAP correct that no dietary supplement is of sufficient quality to recommend for use in preterm infants?

Quality of probiotic dietary supplement probiotics. Dietary supplements were a category of product developed to supplement the diet of the generally healthy population, not to treat or prevent disease. In practice this is an important distinction, because while the safety standard is high for dietary supplements for healthy individuals (see comments by food safety expert Jim Heimbach here), such supplements do not need to be established as safe for patient populations. But in the case of probiotics, many clinical trials have evaluated safety and efficacy for prevention or treatment of disease, more aligned with drug uses. Yet probiotic products supported by these data are not marketed in the US as drugs.

It is a common misperception that dietary supplements are “not regulated”. However, the FDA has clear good manufacturing practices (GMP’s) and regulations dedicated to dietary supplement manufacturing.  The onus is on manufacturers to establish appropriate product specifications based on intended use and risk. Reputable manufactures establish rigorous purity, strength, and identity quality standards consistent with the intended population and sufficient for that use. Products intended for infants, including premature infants, should be manufactured under quality standards more rigorous than those intended for a healthy adult population. For example, Chr. Hansen bases the enhanced specifications for products aimed at infants, and preterm infants, on elements of Codex standards for infant formula, amongst other stringent microbiological criteria. This would include manufacturing the probiotic strain to an “infant” grade, employing stricter environmental monitoring, sanitation, and airflow control throughout the process, careful selection of raw ingredients for infant compatibility, and enhanced testing and purity standards using validated methods at every step. The internal manufacturing standards that Chr. Hansen applies for products intended for infants, and preterm infants, are much stricter than typical dietary supplement standards, and are appropriate for their intended use.

Therefore, there are high quality, safe probiotic products produced under dietary supplement regulations even though such products do not carry any label statement claiming this added level of quality. However, products sourced for hospitals to stock in formularies could work with the supplier to demand this extra level of product testing specifications. Pharmacies can institute quality agreements with vendors that would delineate their expectations for the strains present, the levels of live microbes acceptable in the final product, etc. This agreement could also mandate that any product change – as defined in the agreement – would require the vendor to notify the customer. Such an agreement might be burdensome for a hospital pharmacist, but a sophisticated dietary supplement company should be able to assure the hospital formulary of their quality.

Products made using strict specifications, geared towards infant and premature infant applications, are on the market and are safely being used in this patient population in many NICUs and as part of infant formulas. We disagree with AAP’s position that a pharmaceutical approach is needed, as long as a product of sufficient quality can be provided. To deny preterm infants probiotics, which have a significant chance of improving their clinical outcomes, is not in line with other medical recommendations. Instead, the hospital formularies should stock products that have been scrutinized for sufficient evidence of safety and efficacy. Suppliers of stocked products should provide product testing results, a description of the quality standards employed during production, and a rationale for the suitability of the standards for preterm infants. Third party verification of adherence to these quality standards would assure medical professionals regarding the safety of these products for use.

References

CAC/RCP 66-2008. Code of hygienic practice for powdered formulae for infants and young children. Codex.

Poindexter, B. 2021. Use of Probiotics in Preterm Infants. Pediatrics 147 (6): e202 1051485.

Su et al. 2020. AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders. Gastroenterology 159:697-705.

Van den Akker et al.  2020. Probiotics and Preterm Infants: A Position Paper by the European Society for Paediatric Gastroenterology Hepatology and Nutrition Committee on Nutrition and the European Society for Paediatric Gastroenterology Hepatology and Nutrition Working Group for Probiotics and Prebiotics. Journal of Pediatric Gastroenterology and Nutrition. 70(5):664-680.

 

 

Pharmacists as influencers of probiotic use

/in ISAPP Science Blog /by KC

By Kristina Campbell, science writer

It’s not an uncommon scene in a pharmacy: someone standing in front of the shelf of probiotic products, picking up various bottles and reading the labels, looking uncertain. The person’s doctor may have recommended a certain brand of probiotic to prevent diarrhea with a prescribed course of antibiotics—but they’ve just noticed that the store-brand probiotic, with different strains, is half the price.

Dragana Skokovic-Sunjic

According to Dragana Skokovic-Sunjic, clinical pharmacist and author of the ‘Clinical Guide to Probiotic Products Available in Canada/US’, pharmacists can play an important and influential role helping patients make informed decisions about the available products. “Pharmacists provide a ‘last check validation’ before the patient actually decides to purchase a product,” she says. “And we proactively seek to assist those patients who need help.”

Nardine Nakhla

Nardine Nakhla, clinical pharmacist and Clinical Lecturer at the University of Waterloo School of Pharmacy, says pharmacists often have the knowledge and experience to zero in on which over-the-counter product(s) will or will not work for a certain individual. “Pharmacists have the knowledge and skills to individualize the recommendation based on patient-specific and disease-specific factors, and that is so very important with non-prescription and natural health products because there is no one-size-fits-all approach,” she says.

Can pharmacists apply their knowledge and skills to make specific probiotic recommendations? While it can be hard to narrow the evidence down on specific products, pharmacists can certainly play a role in helping patients understand the evidence for the products they encounter. In a recent interview with ISAPP, Skokovic-Sunjic and Nakhla explained why pharmacists in Canada and elsewhere have the potential to steer people’s choice of over-the-counter and natural health products – including probiotics.

Pharmacists have knowledge about the products on their shelves.

“Advising patients on self-care, which includes over-the-counter and natural health product use, is a key responsibility of Canadian pharmacists. We have North American survey data that shows, for patients who go out and buy non-prescription and natural health products, over 80% never read the label,” says Nakhla.

This means that having a pharmacist available at the point-of-purchase to answer questions can go a long way toward educating people about what’s actually in their hands and how to optimize use, if warranted.

“Having the pharmacist present lets you access somebody who can help inform your decisions—someone who can perhaps steer you away from products that may not be appropriate for you,” she says.

“Pharmacists need to be familiar with the products they are selling at their pharmacies,” adds Skokovic-Sunjic. “They are skilled at asking suitable questions to ensure the patient’s needs and wishes are understood and then to help them choose appropriate over-the-counter, ‘self-selection’ therapy.”

Pharmacists are unique in having non-prescription products within their standards of practice.

As a faculty member at the school of pharmacy, Nakhla emphasizes the requirement for pharmacists to know how to assess and manage patients seeking self-care in the community. She says, “We have a unique body of knowledge where we study non-prescription therapeutics and other self-care measures of disease management and health maintenance,” she says. “Pharmacists are trained to know about these and to recommend evidence-based and cost-effective measures individualized for each patient.”

“It’s explicitly stated under our Standards of Practice that we must be proficient in providing information on non-prescription products, natural health products, and on non-pharmacological measures to enable patients to receive the intended benefit of the therapies, whereas physicians are far more focused on the diagnosis and prescription therapies,” she says.

Pharmacists can identify patients who could benefit from probiotics

Both Nakhla and Skokovic-Sunjic emphasize that pharmacists frequently identify people who could potentially benefit from self-care products, even if they don’t come in looking for them.

Nakhla mentions the probiotic guide authored by Skokovic-Sunjic, and how it helps pharmacists provide helpful solutions to common problems that present in the community. “I think a good strategy is looking at the conditions listed in the probiotic guide and the subsequent products indicated for use for them, and then work backwards to try to identify patients who may benefit from the listed therapies, rather than just wait for them to present asking you questions.”

Pharmacists are in a position to encourage prevention.

“Pharmacy has historically focused on providing reactive healthcare rather than proactive or preventative care,” says Nakhla. But this has recently changed, with a growing emphasis on preventing chronic disease through ongoing health maintenance and self-care strategies. She cites pharmacists as qualified health professionals who encounter many generally healthy people throughout the course of their day, and who are therefore well-positioned to advise the public on how to remain healthy.

Skokovic-Sunjic gives some examples: “If the consumer will be travelling, we might suggest a specific probiotic to prevent traveller’s diarrhea. Or if we are coming to the cold and flu season, we may recommend a product they can take to reduce the risk of developing common infectious diseases.”

Pharmacists can conduct brief or lengthy assessments before providing recommendations.

Skokovic-Sunjic says, “A pharmacist can provide specific recommendations that could really make a big difference in the patient’s experience by quickly asking a few targeted questions. This strategy may save the patient time, money, frustration and sub-optimal health outcomes. When consumers self-select inappropriate products, they will not experience benefits they seek. Determined to choose a natural product, some consumers will try a second or even third product but will not get the symptom relief they are looking for. An unintended consequence of this is that the patient may dismiss the probiotics as ineffective not because they did not work, but because it was the wrong product for the desired effect.”

Brief assessment questions are especially important for probiotics, she adds, because specificity can ‘make or break’ how useful they are to an individual. “In my consultations with patients, I quite often include questions about bowel movements and I know they are questioning why I am asking. Understanding gut function can be extremely helpful in providing appropriate probiotic recommendations.”

Pharmacists can help people understand the concept of ‘evidence-based’.

Nakhla acknowledges it’s difficult for the average person to confront a shelf of probiotic products and delineate between the ones that have evidence backing their use, and the ones that do not. “That’s where I really think a pharmacist needs to intervene and to help them balance out the pros and the cons,” she says.

“If patients are looking for a probiotic to relieve a specific symptom, then looking for an evidence-based recommendation for that specific symptom is needed,” says Skokovic-Sunjic. “If they pick something that’s not supported by evidence, it may not provide symptom relief or the benefit they expect. This may be in addition to wasted funds and mounting frustration.”

Thus, pharmacists are in a unique position to contribute to enhanced awareness about efficacy and “evidence-based self-care” as they explain these concepts to consumers at the point of sale.

 

Given all the potential ways for pharmacists to guide consumer decisions about probiotics, both Skokovic-Sunjic and Nakhla agree that keeping up on the latest probiotic evidence is of high importance.

Through ISAPP’s new efforts to engage with pharmacists, the organization plans to gauge how pharmacists in various parts of the world approach probiotic recommendations, and to support the ‘best case scenario’ of pharmacists providing evidence-based information about probiotics directly to consumers.

Sign up here for ISAPP’s newsletter for pharmacists.

Follow up from ISAPP webinar – Probiotics, prebiotics, synbiotics, postbiotics and fermented foods: how to implement ISAPP consensus definitions

/in ISAPP Science Blog /by KC

By Mary Ellen Sanders PhD, Executive Science Officer, ISAPP

On the heels of the most recent ISAPP consensus paper – this one on postbiotics – ISAPP sponsored a webinar for industry members titled Probiotics, prebiotics, synbiotics, postbiotics and fermented foods: how to implement ISAPP consensus definitions. This webinar featured short presentations outlining definitions and key attributes of these five substances. Ample time remained for the 10 ISAPP board members to field questions from attendees.

When considering the definitions, it’s important to remember that the definition is a starting point – not all criteria can be included. Using the probiotic definition as an example, Prof. Colin Hill noted that the definition is only 15 words – Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. This is a useful definition, stipulating the core characteristics of a probiotic. However, important criteria such as safety and identity are not specified in the definition yet are clearly delineated in the full paper on probiotics.

Several interesting topics emerged from this discussion, which will be explored in future blog posts. These include:

  • What is meant by host health? Microbe mediated benefits are numerous. But not all benefits are a benefit to host health. Benefits for user appearance, pets and potentially livestock may be measurable, economically important and desirable, but may not encompass ‘host health’.
  • What types of endpoints are appropriate for studies to meet the requirement of a health benefit? Endpoints that indicate improved health (such as symptom alleviation, reduced incidence of infections or quality of life measures) are targeted. Some physiological measures that may be linked to health (such as increased fecal short chain fatty acids or changes in microbiota composition) may not be sufficient.
  • What are the regulatory implications from these definitions? As suggested by the National Law Review article on the ISAPP consensus definitions, attorneys are interested in the scientific positions on how these terms are defined and characterized. Further, some regulatory actions – such as by Codex Alimentarius in defining probiotics – are underway. ISAPP is open to suggestions about the best way to communicate these definitions to regulators.
  • Is any follow-up by ISAPP to these papers anticipated in order to clarify criteria and provide simple guidance to their implementation?

Simple guidance to these substances can be found in the infographics: probiotics, probiotic criteria, prebiotics, fermented foods,  how are probiotic foods and fermented foods different, synbiotics, and postbiotics. As mentioned above, watch for blog updates on implementation of the definitions for different stakeholder groups.

The recording of this webinar is available here under password protection for ISAPP industry members only.

Related information:

Consensus panel papers, all published in Nature Reviews Gastroenterology and Hepatology:

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

 

 

 

 

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

/in ISAPP Science Blog /by KC

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’

Behind the publication: Understanding ISAPP’s new scientific consensus definition of postbiotics

/in ISAPP Science Blog /by KC

A key characteristic of a probiotic is that it remains alive at the time of consumption. Yet scientists have known for decades that some non-living microorganisms can also have benefits for health: various studies (reviewed in Ouwehand & Salminen, 1998) have compared the health effects of viable and non-viable bacteria, and some recent investigations have tested the health benefits of pasteurized bacteria (Depommier et al., 2019).

Since non-viable microorganisms are often more stable and convenient to include in consumer products, interest in these ‘postbiotic’ ingredients has increased over the past several years. But before now, the scientific community had not yet united around a definition, nor had it precisely delineated what falls into this category.

An international group of scientists from the disciplines of probiotics and postbiotics, food technology, adult and pediatric gastroenterology, pediatrics, metabolomics, regulatory affairs, microbiology, functional genomics, cellular physiology and immunology met in 2019 to discuss the concept of postbiotics. This meeting led to a recently published consensus paper, including this definition: “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”.

Thus, a postbiotic must include some non-living microbial biomass, whether it be whole microbial cells or cell components.

Below is a Q&A with four of the paper’s seven ISAPP-linked authors, who highlight important points about the definition and explain how it will lay the groundwork for better scientific understanding of non-viable microbes and health in the years ahead.

Why was the concept of postbiotics needed?

Prof. Seppo Salminen, University of Turku, Finland:

We have known for a long time that inactivated microorganisms, not just live ones, may have health effects but the field had not coalesced around a term to use to describe such products or the key criteria applicable to them. So we felt we needed to assemble key experts in the field and provide clear definitions and criteria.

Further, novel microbes (that is, new species hitherto not used in foods) in foods and feeds are being introduced as live or dead preparations. The paper highlights regulatory challenges and for safety and health effect assessment for dead preparations of microbes.

Can bacterial metabolites be postbiotics?

Prof. Gabriel Vinderola, National University of Litoral, Argentina:

Postbiotics can include metabolites – for example, fermented products with metabolites and microbial cells or their components, but pure metabolites are not postbiotics.

Can you expand on what is not included in the category of postbiotics?

Dr. Mary Ellen Sanders, ISAPP Executive Science Officer, USA:

The term ‘postbiotic’ today is sometimes applied to components derived from microbial growth that are purified, so no cell or cell products remain. The panel made the decision that such purified, microbe-derived substances (e.g. butyrate) should be called by their chemical names and that there was no need for a single encompassing term for them. Some people may be surprised by this. But microbe-derived substances include a whole host of purified pharmaceuticals and industrial chemicals, and these are not appropriately within the scope of ‘postbiotics’.

For something to be a postbiotic, what kinds of microorganisms can it originate from?

Prof. Gabriel Vinderola, National University of Litoral, Argentina:

A postbiotic must derive from a living microorganism on which a technological process is applied for life termination (heat, high pressure, oxygen exposure for strict anaerobes, etc). Viruses, including bacteriophages, are not considered living microorganisms, so postbiotics cannot be derived from them.

Safety and benefits must be demonstrated for its non-viable form. A postbiotic does not have to be derived from a probiotic (see here for a list of criteria required for a probiotic). So the microbe used to derive a postbiotic does not need to demonstrate a health benefit while alive. Further, a probiotic product that loses cell viability during storage does not automatically qualify as a postbiotic; studies on the health benefit of the inactivated probiotic are still required.

Vaccines or substantially purified components and products (for example, proteins, peptides, exopolysaccharides, SCFAs, filtrates without cell components and chemically synthesized compounds) would not qualify as postbiotics in their own right, although some might be present in postbiotic preparations.

What was the most challenging part of creating this definition?

Dr. Mary Ellen Sanders, ISAPP Executive Science Officer, USA:

The panel didn’t want to use the term ‘inactive’ to describe a postbiotic, because clearly even though they are dead, they retain biological activity. There was a lot of discussion about the word ‘inanimate’, as it’s not so easy to translate. But the panel eventually decided it was the best option.

 Does this definition encompass all postbiotic products, no matter whether they are taken as dietary supplements or drugs?

Prof. Hania Szajewska, Medical University of Warsaw, Poland:

Indeed. However, as of today, postbiotics are found primarily in foods and dietary supplements.

Where can you currently find postbiotics in consumer products, and what are their health effects?

Prof. Hania Szajewska, Medical University of Warsaw, Poland:

One example is specific fermented infant formulas with postbiotics which have been commercially available in some countries such as Japan and in Europe, South America, and the Middle East for years. The postbiotics in fermented formulas are generally derived from fermentation of a milk matrix by Bifidobacterium, Streptococcus, and/or Lactobacillus strains.

Potential clinical effects of postbiotics include prevention of common infectious diseases such as upper respiratory tract infections and acute gastroenteritis. Moreover, fermented formulas have the potential to improve some digestive symptoms or discomfort (e.g. colic in infants). In addition, there is some rationale for immunomodulating, anti-inflammatory effects which may potentially translate into other clinical benefits, such as improving allergy symptoms. Still, while these effects are likely, more well-designed, carefully conducted trials are needed.

What do we know about postbiotic safety?

Dr. Mary Ellen Sanders, ISAPP Executive Science Officer, USA:

Living microbes have the potential, especially in people with compromised health, to cause an infection. But because the microbes in postbiotics are not alive, they cannot cause infections. This risk factor, then, is removed from these preparations. Of course, the safety of postbiotics for their intended use must be demonstrated, but infectivity should not be a concern.

What are the take-home points about the postbiotics definition?

Prof. Seppo Salminen, University of Turku, Finland:

Postbiotics, which encompass inanimate microbes with or without metabolites, can be characterized, are likely to be more stable than live counterparts and are less likely to be a safety concern, since dead bacteria and yeast are not infective.

Read the postbiotic definition paper here.

See the press release about this paper here.

View an infographic on the postbiotic definition here.

See another ISAPP publication on postbiotics here.