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Archive Highlight: Biotics in animal and human nutrition, with Prof. Kelly Swanson PhD

/in Podcast, Season Three /by Laura

 

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Completing our series on the role of biotics in animal health, we are highlighting Episode 22 from our archives. In this episode, Prof. Kelly Swanson PhD from University of Illinois at Urbana-Champaign discusses the role of biotics in animal and human nutrition. He reviews the criteria for prebiotics and synbiotics, then discusses how we gain knowledge about nutrition and the role of biotics in animals compared to humans.

Key topics from this episode:

  • A good argument can be made that biotics are essential for our diet; they are beneficial even if efficacy is sometimes difficult to prove.
  • Nutrients have an impact on the host’s health and simultaneously on the host-associated microbes.
  • Health benefits are essential to the FDA definition of fiber.
  • Antibiotics’ effect on the microbiota: short-term effects may be minor, but we still don’t know the long-term effects.
  • The synbiotics definition, criteria for products to meet this definition, and the health outcomes from using these biotic substances.
  • The difference between complementary and synergistic synbiotics.
  • When studying biotics in companion animals (cats and dogs), can results from one host be extrapolated to another host? Final studies should be in the target host.
  • Biotics are important in veterinary medicine and a popular topic of study.
  • Predictions about the future of nutrition science as informed by the microbiome.

Episode links:

Additional resources:

About Prof. Kelly Swanson:

Kelly Swanson is the Kraft Heinz Company Endowed Professor in Human Nutrition at the University of Illinois at Urbana-Champaign. His laboratory studies the effects of nutritional interventions, identifying how diet impacts host physiology and gut microbiota. His lab’s primary emphasis is on gastrointestinal health and obesity in dogs, cats, and humans. Much of his work has focused on dietary fibers and ‘biotics’. Kelly has trained over 40 graduate students and postdocs, published over 235 peer-reviewed manuscripts, and given over 150 invited lectures at scientific conferences. He is an active instructor, teaching 3-4 nutrition courses annually, and has been named to the university’s ‘List of Teachers Ranked as Excellent by Their Students’ 30 times. He serves on advisory boards for many companies in the human and pet food industries and non-profit organizations, including the Institute for the Advancement of Food and Nutrition Sciences and International Scientific Association for Probiotics and Prebiotics.

Discovering novel bioactive peptides in fermented foods

/in ISAPP Science Blog /by KC

By Dr. Rounak Chourasia PhD, National Agri-food Biotechnology Institute, Mohali, Punjab, India

Food not only serves as a primary source of essential nutrients but also contains a wealth of potential bioactive compounds. Among these, peptides have garnered significant attention for their ability to impact health beyond basic nutrition. These short protein fragments, ranging from 2 to 20 amino acids, play critical roles in physiological functions and exhibit diverse health benefits, making them increasingly interesting to researchers and consumers. Food-derived bioactive peptides are especially promising due to their environmentally friendly production, lack of accumulation in the body, low toxicity, and biodegradability, making them appealing for safe and sustainable therapeutic alternative to synthetic compounds.

Fermented foods have recently gained renewed interest for their potential health benefits. One proposed way that fermented foods may confer health benefits is through bioactive compounds released by the catalytic action of fermenting microbes on the food substrate. Protein-rich food substrates are especially valuable for the release of bioactive peptides through fermentation. Microbial strains associated with food fermentation have diverse proteolytic capacities, leading to a unique peptidome for each fermented food produced using different microbial starter cultures. For example, Ile-Pro-Pro and Val-Pro-Pro are well-known milk-derived bioactive peptides with diverse health benefits (1). These tripeptides are available in several health supplements and functional foods, marketed for their ability to improve cardiovascular function by inhibiting angiotensin-I converting enzyme (ACE). Additionally, these tripeptides exert antioxidant and immunomodulatory properties. Discovering novel multifunctional peptides from fermented foods is a desirable goal for research aimed at maintaining a healthy lifestyle and preventing metabolic diseases.

In our research, we have identified both previously reported and novel bioactive peptides with diverse functional attributes from alkaline and acidic fermented foods of the Indian Himalayan regions, such as Chhurpi cheese and Kinema (fermented soybeans) (2, 3). These traditionally fermented foods are rich sources of bioactive peptides with potential health benefits. Chhurpi cheese, a fermented dairy product, and Kinema, a fermented soybean product, both exhibit a unique array of bioactive peptides due to the specific microbial strains involved in their fermentation. The identification of these peptides may enhance the functional value of these traditional foods and provides opportunities to explore the resident fermentation microorganisms for the development of novel functional foods.

Conventional methods for identifying novel peptides in fermented foods and validating their biological activity involve expensive and labor-intensive processes. These include the purification of bioactive fractions followed by LC-MS/MS-based identification and the synthesis of each individual peptide for bioactivity validation. However, the advent of in silico tools and machine learning models has made it faster and more affordable to predict the bioactivity of peptides identified by untargeted LC-MS/MS analysis (4). Qualitative and quantitative in silico tools, such as molecular docking, dynamics simulation, and structure-activity relationship models, help select specific peptides identified in fermented foods for validation of their bioactivity after synthesis. Nevertheless, these machine learning models require refinement and further improvement to achieve accurate predictions. Additionally, in silico tools such as Peptigram help us understand the proteolytic specificity of food-fermenting microorganisms, enabling the development of specific microbial starters for the production of fermented foods enriched with peptides for the prevention of targeted diseases.

One significant concern in the application of bioactive peptides is their bioavailability. Once ingested, these peptides are subject to hydrolysis in the gastrointestinal tract, which can lead to the loss of their bioactivity. The stability of these peptides in the bloodstream is also crucial, as they must remain intact to exert their beneficial effects. Thus, it is necessary to find solutions to accurately predict the susceptibility of peptides to gut hydrolysis and their pharmacokinetics in the blood. Advanced techniques and models are required to better understand and enhance the bioavailability of these peptides, ensuring that their health benefits are preserved from ingestion to absorption and systemic circulation.

The discovery of novel bioactive peptides from fermented foods has the potential to contribute to the development of functional foods with enhanced health benefits. As research advances, the integration of traditional fermentation processes with modern biotechnological tools promises to unlock new potential for supporting health through nutrition.

Woman holding yogurt. In the US, yogurt now has an approved Qualified Health Claim.

A guide to the new FDA Qualified Health Claim for yogurt

/in ISAPP Science Blog /by KC

Fermented foods such as yogurt, kimchi, and fermented pickles have traditionally been associated with health benefits in countries around the world, but the science that backs these health benefits is relatively new.

Amidst a growing number of scientific studies examining the health benefits of specific fermented foods, a new Food and Drug Administration (FDA) announcement in the US marks an advance in how the potential benefits of fermented foods can be portrayed to the general public.

In response to a petition by Danone North America, the FDA announced that it will allow the first Qualified Health Claim related to a fermented food – yogurt. The new Qualified Health Claim is worded as follows:

Eating yogurt regularly, at least 2 cups (3 servings) per week, may reduce the risk of type 2 diabetes. FDA has concluded there is limited information supporting this claim.

Or Eating yogurt regularly, at least 2 cups (3 servings) per week, may reduce the risk of type 2 diabetes according to limited scientific evidence.

The claim was announced in a letter of enforcement discretion on March 1st, and can be applied to any yogurt product on the US market that meets the FDA’s standards of identity.

Qualified Health Claims and why they’re important

A Qualified Health Claim is a statement that makes a connection between a substance and a disease-related or health-related condition, is supported by scientific evidence, but does not meet the more rigorous “significant scientific agreement” standard required for an Authorized Health Claim.

Currently, approximately one dozen Authorized Health Claims and around 30 Qualified Health Claims exist in the US for different nutritional and food substances. For example, an Authorized Health Claim exists for soluble fiber from whole oats; Qualified Health Claims exist for walnuts, green tea, and a list of other foods.

To ensure that these claims are not misleading, they must be accompanied by a disclaimer or other qualifying language to accurately communicate to consumers the level of scientific evidence supporting the claim.

According to Bob Hutkins, Professor Emeritus at the University of Nebraska-Lincoln, such claims are important when considered within the context of what Americans currently eat.

He says, “We come nowhere close to eating the recommended amounts of fiber, whole grains, and fruits and vegetables. Indeed, according to the USDA Healthy Eating Index, the average consumer scores a 60 on a 100 point scale. When considering our overall eating habits in the US, I don’t know that this one claim will actually move the needle very much. But in my view, health claims, whether ‘Authorized’ or ‘Qualified’, may help nudge consumers to make informed decisions when deciding what to eat.”

The path to Qualified Health Claim

Dr. Miguel Freitas PhD, VP Health and Scientific Affairs at Danone North America, whose team led the petition, says the company’s efforts were motivated by the observation that, over time, evidence supporting the potential of yogurt to reduce the risk of type 2 diabetes grew more and more compelling.

In December 2018, Danone North America first submitted the Qualified Health Claim petition to the FDA. The petition was put on hold during the height of the COVID-19 pandemic and the evidence was reviewed again in 2023 by the FDA.

In total, more than 85 related studies were considered in support of the claim, with 30 being deemed high or moderate quality.

The FDA gave recognition of the claim in March 2024. Dr. Freitas says, “Now that the claim has been announced, our hope is that it will give consumers simple, actionable information they can use to reduce their risk of developing type 2 diabetes through an easily achievable, realistic dietary modification.”

Scientific support

Prof. Hutkins says the FDA has a high bar even for Qualified Health Claims, requiring a substantial level of scientific evidence to support them. He says that regarding this yogurt claim, “The FDA conducted an exhaustive review of studies that were included in the petition. Many of the studies were not considered rigorous enough and were excluded. In my view, they were very conservative in their analysis of the data.”

Both intervention studies and observational studies were considered in the FDA’s evaluation of the evidence linking yogurt and type 2 diabetes. Pro. Hutkins says that while randomized, controlled trials (RCTs) are considered the gold standard, well-conducted observational studies in large human cohorts can be very informative. The latter ended up being the sole basis of the FDA decision.

“The FDA identified 20 relevant intervention studies, but none were considered sufficiently rigorous to draw meaningful conclusions,” he says. “The FDA identified 28 relevant observational studies, which were then critically reviewed. Ultimately they concluded there was sufficient credible data to suggest associations of yogurt consumption on reduced incidence type 2 diabetes.”

The language for Qualified Health Claims includes any relevant qualifications indicated by the evidence. The FDA claim wording does not differentiate between sweetened and unsweetened yogurt products, with the evaluation noting that the beneficial association was observed irrespective of fat or sugar content. Nevertheless, Prof. Hutkins advises paying attention to the overall nutritional profile of different yogurt products, “In my view consumers could gain the benefits of yogurt without the extra calories and refined carbohydrates by choosing unsweetened yogurts.”

Implications for the food industry

Dr. Freitas says, “Our hope is that this new Qualified Health Claim will inspire the food industry as a whole to increase its focus on yogurt innovation and research, to continue unlocking the full extent of its potential benefits.”

Meanwhile, Prof. Hutkins hopes to see more RCTs on yogurt in the future. “It should be possible to design RCTs that would satisfy the FDA,” he says. “I hope funding agencies will agree.”

Prof. Seppo Salminen PhD, from University of Turku (Finland), says this approval may mark the beginning of a trend in developing claims for individual fermented foods. Such is the goal of a European project called Promoting Innovation of ferMENTed fOods (PIMENTO), which acknowledges the high consumer interest in fermented foods and the potential benefits of these foods for nutrition, sustainability, and more. Prof. Salminen points out that yogurt is leading the way, given the new US claim as well as the existing European Union claim regarding yogurt with live cultures and improved lactose digestion.

Fermented Food Microbiology Researcher in Mohali, India Receives 2024 Gregor Reid Award for Outstanding Scholars in Developing Nations

/in News /by KC

ISAPP’s board of directors is happy to announce the 2024 winner of the Gregor Reid Award for Outstanding Scholars in Developing Nations: Dr. Rounak Chourasia PhD, a research associate at the National Agri-food Biotechnology Institute in Mohali, Punjab (India).

Dr. Chourasia’s work focuses on discovering microorganisms with specific properties that contribute to the enhanced health benefits of a traditional cheese called chhurpi from Sikkim Himalaya (a state in Northeast India). He has developed a process for the production of milk cheese using selected strains of lactic acid bacteria, resulting in the release of novel bioactive peptides with potential nutraceutical applications. Furthermore, he has applied selected microbial strains to develop bioactive peptide-enriched novel soybean cheese suitable for those with lactose intolerance. The research has not only contributed to knowledge about the functional properties of chhurpi, but has also provided a foundation for helping local farmers expand their entrepreneurial opportunities.

Dr. Chourasia received both a Bachelor and Master of Science in microbiology from the University of North Bengal, India, followed by a PhD in biotechnology in 2023 from the Institute of Bioresources and Sustainable Development (DBT-IBSD), regional centre, Sikkim, and Kalinga Institute of Industrial Technology (KIIT) University under the guidance of Dr. Amit Kumar Rai and Prof. Dinabandhu Sahoo.

The 2024 committee selected Dr. Chourasia from among the many qualified candidates for the Gregor Reid Award for Outstanding Scholars in Developing Nations in this inaugural year. ISAPP established the award in honor of Dr. Gregor Reid PhD, for the purpose of recognizing and supporting early career researchers within low and middle income countries (LMICs). Dr. Reid is a founding board member of ISAPP, former President of ISAPP, and founder of the ISAPP Students and Fellows Association (SFA), whose work in LMICs throughout his career showed his commitment to scientific excellence, innovation, and community development.

Dr. Chourasia will receive an award plaque and will speak about his work at the ISAPP annual meeting in July, 2024.

Episode 27: Investigating the benefits of live dietary microbes

/in Podcast, Season Two /by Laura

 

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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 Prebiotics (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

Investigating the benefits of live dietary microbes, with Prof. Colin Hill PhD and Prof. Dan Tancredi PhD

Episode summary:

In this episode, the ISAPP podcast hosts themselves are the experts: Prof. Colin Hill PhD from APC Microbiome Ireland / University College Cork and Prof. Dan Tancredi PhD from University of California – Davis talk about their recent work investigating the health benefits from consuming higher quantities of live dietary microbes – and not just microbes that meet the probiotic criteria.

Key topics from this episode:

  • Profs. Hill and Tancredi were involved with others in a recent series investigations & 3 published papers on whether there should be a recommended daily intake of live microbes.
  • Prof. Hill started by writing a blog, prompted by the finding that meta-analyses on probiotics tended to show some general benefits for health. Would this apply to any safe, live microbes – even those that do not meet the probiotic criteria?
  • Various hypotheses (hygiene hypothesis, old friends hypothesis, missing microbes hypothesis) posit that a lack of microbes is associated with poorer health.
  • Clean water and clean food have reduced the burden of infectious disease. But at the same time, across populations there has been an increase in chronic diseases. Could a lack of live dietary microbes be contributing to this increase in chronic disease, because the immune system lacks adequate inputs? Or in other words, could there be a general health benefit for healthy people in consuming high quantities of live microbes?
  • To address the hypothesis scientifically: they investigated the health status of people who eat large vs. small numbers of safe live microbes in their diets. Starting with NHANES data in the US, the researchers classified foods into categories of high / medium / low numbers of live microbes.
  • Note that not all fermented foods contain live microbes, but some contain high numbers of live microbes. A possible confounding factor in the analysis was that high microbe foods tend to be healthier foods.
  • The researchers published a series of 3 papers. The 3rd paper showed an association between intake of live microbes and various (positive) measurements of health. Consistent, modest improvements were seen across a range of health outcomes.
  • This is an association, but statistically the team did use regression analysis to statistically adjust for effects on health that could be due to other factors besides the live microbial intake.
  • The take-home is not to eat unsafe or rotten food, but rather to eat more high-microbe or fermented foods, and in general eat a healthy diet.

Episode links:

Additional Resources:

Live Dietary Microbes: A role in human health. ISAPP infographic.

About Prof. Colin Hill PhD:
Colin Hill has a Ph.D in molecular microbiology and is a Professor in the School of Microbiology at University College Cork, Ireland. He is also a founding Principal Investigator in APC Microbiome Ireland, a large research centre devoted to the study of the role of the gut microbiota in health and disease. His main interests lie in the role of the microbiome in human and animal health. He is particularly interested in the effects of probiotics, bacteriocins, and bacteriophage. In 2005 Prof. Hill was awarded a D.Sc by the National University of Ireland in recognition of his contributions to research. In 2009 he was elected to the Royal Irish Academy and in 2010 he received the Metchnikoff Prize in Microbiology and was elected to the American Academy of Microbiology. He has published more than 600 papers and holds 25 patents. More than 80 PhD students have been trained in his laboratory. He was president of ISAPP from 2012-2015.

About Prof. Dan Tancredi PhD:
Daniel J. Tancredi, PhD, is Professor in Residence of Pediatrics in the University of California, Davis School of Medicine. He has over 25 years of experience and over 300 peer-reviewed publications as a statistician collaborating on a variety of health-related research. A frequent collaborator on probiotic and prebiotic research, he has attended all but one ISAPP annual meeting since 2009 as an invited expert. In 2020, he joined the ISAPP Board of Directors. Colin Hill and Daniel co-host the ISAPP Podcast Series “Science, Microbes, and Health”. On research teams, he develops and helps implement effective study designs and statistical analysis plans, especially in settings with clusters of longitudinal or otherwise correlated measurements, including cluster-randomized trials, surveys that use complex probability sampling techniques, and epidemiological research. He teaches statistics and critical appraisal of evidence to resident physicians; graduate students in biostatistics, epidemiology, and nursing; and professional scientists. Dan grew up in the American Midwest, in Kansas City, Missouri, and holds a bachelor’s degree in behavioral science from the University of Chicago and masters and doctoral degrees in mathematics from the University of Illinois at Chicago. He lives in the small Northern California city of Davis, with his wife Laurel Beckett (UC Davis Distinguished Professor Emerita), their Samoyed dogs Simka and Milka, and near their two grandkids.

Biotics in animal and human nutrition

Episode 22: Biotics in animal and human nutrition

/in Podcast, Season Two /by Laura

Biotics in animal and human nutrition

 

Podcast: Play in new window | Download

Subscribe: Apple 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 Prebiotics (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

Biotics in animal and human nutrition, with Prof. Kelly Swanson

Episode summary:

In this episode, the ISAPP podcast hosts join guest Prof. Kelly Swanson PhD from University of Illinois at Urbana-Champaign, to discuss the role of biotics in animal and human nutrition. They review the criteria for prebiotics and synbiotics, then discuss how we gain knowledge about nutrition and the role of biotics in animals compared to humans.

Key topics from this episode:

  • A good argument can be made that biotics are essential for our diet; they are beneficial even if efficacy is sometimes difficult to prove.
  • Nutrients have an impact on the host’s health and simultaneously on the host-associated microbes.
  • Health benefits are essential to the FDA definition of fiber.
  • Antibiotics’ effect on the microbiota: short-term effects may be minor, but we still don’t know the long-term effects.
  • The synbiotics definition, criteria for products to meet this definition, and the health outcomes from using these biotic substances.
  • The difference between complementary and synergistic synbiotics.
  • When studying biotics in companion animals (cats and dogs), can results from one host be extrapolated to another host? Final studies should be in the target host.
  • Biotics are important in veterinary medicine and a popular topic of study.
  • Predictions about the future of nutrition science as informed by the microbiome.

Episode links:

Additional resources:

About Prof. Kelly Swanson:

Kelly Swanson is the Kraft Heinz Company Endowed Professor in Human Nutrition at the University of Illinois at Urbana-Champaign. His laboratory studies the effects of nutritional interventions, identifying how diet impacts host physiology and gut microbiota. His lab’s primary emphasis is on gastrointestinal health and obesity in dogs, cats, and humans. Much of his work has focused on dietary fibers and ‘biotics’. Kelly has trained over 40 graduate students and postdocs, published over 235 peer-reviewed manuscripts, and given over 150 invited lectures at scientific conferences. He is an active instructor, teaching 3-4 nutrition courses annually, and has been named to the university’s ‘List of Teachers Ranked as Excellent by Their Students’ 30 times. He serves on advisory boards for many companies in the human and pet food industries and non-profit organizations, including the Institute for the Advancement of Food and Nutrition Sciences and International Scientific Association for Probiotics and Prebiotics.

Genetically modified microorganisms for health

Episode 21: Genetically modified microorganisms for health

/in Podcast, Season Two /by Laura

Genetically modified microorganisms for health

 

Podcast: Play in new window | Download

Subscribe: Apple 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 Prebiotics (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

Genetically modified microorganisms for health, with Dr. Carlos Gómez-Gallego

Episode summary:

In this episode, ISAPP podcast host Dan Tancredi joins guest Carlos Gómez-Gallego PhD, from University of Eastern Finland, to discuss genetically modified microorganisms. They go over what genetically modified microorganisms are, their potential benefits over non-modified microorganisms, and how they might improve human health–in particular, diseases of the metabolic and immune systems.

 

Key topics from this episode:

  • Genetically modified microorganisms are those that have been modified using genetic engineering, giving them abilities they do not normally have. Functions can be either conferred or deleted. Different genetic engineering tools can be used – e.g. to make them produce therapeutic compounds, or make them increase degradation of toxins or harmful compounds.
  • One advantage over non-modified microorganisms is the potential to have continuous delivery of a therapeutic compound, and the potential to deliver it to a localized area in order to avoid unwanted interactions.
  • Genetically modified microorganisms have promise in metabolic and immune-linked disorders such as non-alcoholic fatty liver disease (NAFLD).
  • In NAFLD, genetically modified E. coli Nissle can secrete hormones that are under-regulated or under-expressed. His group modified bacteria by introducing a plasmid that allowed it to produce aldafermin, an analog of the human hormone fibroblast growth factor 19 (FGF19).
  • With genetically engineered microorganisms, we must consider the benefits but also the risks. However, if it’s a therapeutic for a disease with few or no alternatives, there’s a strong case for developing them.
  • To increase efficacy and safety of these microorganisms, it’s possible to introduce sensors that produce the therapeutic in response to different stimuli. Also, it’s important to modify the bacteria so their use is controlled and they cannot spread. They can also be modified to avoid transmission of genes.
  • Are there market-approved genetically modified microorganisms? No approved ones yet, but some are in Phase 1 and Phase 2 clinical trials.

Episode links:

About Dr. Carlos Gómez-Gallego:

I am a Senior Researcher at the Institute of Public Health and Clinical Nutrition (University of Eastern Finland). I have completed two university degrees, one in Biology and another in Food Science and Technology, and an MSc in Nutrition and Health. I subsequently completed a Ph.D. from the University of Murcia, where I investigated the effect of infant formula processing on the content of polyamines and bioactive peptides, and their impact on intestinal microbiota and immune system development during lactation.

My research and interests are primarily focused on advancing the understanding of the impact of diet, food, and bioactive compounds on human microbiota and their association with human health. As part of the BestTreat project (https://besttreat.eu/index.html), I have co-supervised two PhD students (Johnson Lok and Valeria Ianone) who evaluated the potential use of engineered E. coli Nissle 1917 producing human hormones for the treatment of non-alcoholic fatty liver disease (NAFLD) in a mouse model. The first publication has already been submitted, and the second is currently in process.

More info about my publications:
Research Gate https://www.researchgate.net/profile/Carlos-Gomez-Gallego
UEF connect https://uefconnect.uef.fi/en/person/carlos.gomez-gallego/#information

Episode 18: The definition of postbiotics

/in Podcast, Season Two /by Laura

 

Podcast: Play in new window | Download

Subscribe: Apple 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 Prebiotics (ISAPP), a nonprofit scientific organization dedicated to advancing the science of these fields.

The definition of postbiotics, with Dr. Gabriel Vinderola and Prof. Seppo Salminen

Episode summary:

In this episode, the ISAPP podcast hosts join guests Gabriel Vinderola, PhD, Principal Researcher at the
National Scientific and Technical Research Council (CONICET) and Associate Professor at University of Litoral in Argentina, and Seppo Salminen, PhD, Professor at University of Turku in Finland, to discuss the relatively recent definition of postbiotics and what kinds of substances are included in this category. They talk about the criteria for something to qualify as a postbiotic, common mechanisms of action for postbiotics, and how postbiotic science has brought new perspectives on the study of probiotics.

 

Key topics from this episode:

  • What are postbiotics? Dr. Vinderola and Prof. Salminen dive deep into the definition of postbiotics created in 2021 and what it entails.
  • Postbiotics, similar to probiotics, prebiotics, and synbiotics, must provide health benefits to the host.
  • The nature of the postbiotic preparation is important for its health benefits. When the inactivation process is changed, this can lead to altered health benefits, and clinical studies must be repeated to ensure the desired health benefits are maintained.
  • They explain why “inanimate” was chosen to describe the microorganisms / components in a postbiotic preparation. 
  • What is the mode of action, or how do postbiotics work? 
    • Postbiotics show similar mechanisms of action to probiotics, except for ones requiring viability, since postbiotics will not grow and produce metabolic byproducts in the host.
    • Postbiotics can benefit the host via physical interaction with the host epithelial and immune cells.
    • A primary mechanism of action is likely to be through activation of the immune system, through which postbiotics can affect inflammation and some disease conditions. 
    • Postbiotics may also affect the microbiome composition and ability to inhibit pathogens.
  • From a regulatory point of view, inanimate microorganisms may represent an easier category to prove safe for users. For industry, postbiotics may be more convenient with a longer shelf life.
  • Some controversy still exists around the ISAPP-led postbiotic definition, and this has led to valuable discussions that are crucial to scientific progress. So far the authors of the definition have defended their stance.

 

Episode abbreviations and links:

 

Additional Resources:

Postbiotics. ISAPP infographic (also available in Japanese and Spanish).

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

Definition of postbiotics: A panel debate in Amsterdam. ISAPP blog post.

 

About Dr. Gabriel Vinderola: 

Gabriel Vinderola graduated at the Faculty of Chemical Engineering from the National University of Litoral (Santa Fe, Argentina) in 1997. He obtained his Ph.D. in Chemistry in 2002 at the same University. He collaborated with several research teams in Canada, Spain, France, Italy, Germany, Brazil and Finland. He is presently Principal Researcher of the National Scientific and Technical Research Council (CONICET) and Associate Professor at the Food Engineering Department of his home Faculty. He participated in 1999 in the development of the first commercial cheese carrying probiotic bacteria in Latin America. In 2011, he was awarded the prize in Food Technology for young scientists, by the National Academy of Natural, Physic and Exact Sciences from Argentina. He published more than 120 original scientific publications in international refereed journals and book chapters. From 2020 to present, he serves as a member of the board of directors of the International Scientific Association for Probiotics and Prebiotcis (ISAPP). He is engaged in science communication to the general public through Instagram (@gvinde).

 

About Prof. Seppo Salminen: 

Seppo Salminen, MSc, MS, PhD, is a Senior Advisor, Functional Foods Forum (FFF) at the University of Turku. His areas of expertise are gut microbiota, probiotics and prebiotics, nutrition and food safety, and EU regulations. Seppo teaches the topics of lactic acid biotechnology, functional foods and EU legislation and conducts research into food and health, intestinal microbiota, probiotics, prebiotics, functional foods, food legislation, health claims, and novel foods.

Picture of panelists on stage with conference participants in the audience

Definition of postbiotics: A panel debate in Amsterdam

/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 the Dairy Products Institute (CONICET-UNL), Santa Fe, Argentina.

A panel debate titled “Postbiotics, definition and scopes” was convened at the 9th Beneficial Microbes conference in Amsterdam on November 14, 2022. The aim of this panel was to advance the discussion about postbiotics in the aftermath of some published disagreement (see here and here) about the definition of postbiotics produced and published by ISAPP: “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”. The debaters included Prof. Seppo Salminen and myself (Dr. Gabriel Vinderola), both members of the board of directors of ISAPP and co-authors of the ISAPP postbiotics definition, supporting the ISAPP definition, and Prof. Lorenzo Morelli (in attendance virtually) and Dr. Guus Roeselers challenging the ISAPP definition. The debate was attended by around 150 persons, and consisted of 15-minute opening arguments on both sides, followed by a 30 min open discussion guided by the conference chair, Dr. Koen Venema.

I introduced ISAPP as a non-profit organization dedicated to advancing the science on probiotics, prebiotics and related substances. Among many other activities, ISAPP has produced 5 different consensus definitions: probiotics, prebiotics, synbiotics, postbiotics and fermented foods. Each consensus panel was composed of academic scientists with different backgrounds, expertise and perspectives, comprising at least 11 authors from 4 – 10 countries, who came together to incorporate broad perspectives and engage in thoughtful debate. To date, all 5 consensus papers have had almost half a millon accesses at Nature Reviews Gastroentetology and Hepatology, the journal where all of the definitions are published.

The discussion within ISAPP about the need for a postbiotic definition dates back to our 2019 annual meeting. Emerging research on the health benefits conferred by non-viable microbes, their fragments and metabolites was discussed at the meeting, and this planted the seed for a definition that would cover this area. Many different terms such as heat-killed probiotics, heat-treated probiotics, heat-inactivated probiotics, tyndallized probiotics, paraprobiotics, ghost probiotics, cell fragments, cell lysates and postbiotics had been used to encompass these substances.

The panel discussed these different terms and previously published definitions. Those opposed to the ISAPP definition preferred the Tsilingiri and Rescigno (2013)1 definition of postbiotics, which focuses on metabolites produced by probiotics. I reviewed the limitations of that definition, which were outlined in Salminen et al. (2021)2. One concern is that requiring a postbiotic to be derived from a probiotic creates an unnecessary burden of first meeting the criteria for a probiotic before developing a postbiotic.

Morelli emphasized the importance of definitions for regulatory bodies and stated that researchers should provide guidance on criteria to meet a definition. He quoted the first published definition of postbiotic by Tsilingiri and Rescigno in 20131: “any factor resulting from the metabolic activity of a probiotic or any released molecule capable of conferring beneficial effects to the host in a direct or indirect way”. Morelli stated that one value of this definition was that it was clear to regulators; metabolites are measurable and produced by microbes already accepted as food components with a long history of safe use. He considered this of paramount relevance as otherwise, the novel foods path would be required. He challenged the ISAPP approach as defining a substance that was unclear how to measure. Morelli showed pictures depicting the deterioration of the biomass of freeze-dried cultures during storage, to underscore the challenges of controlling the quality of products based on biomass of non-viable microbes. He added, “If we don´t know which are the components responsible for the health benefits, then it is challenging to determine what to measure.” He questioned the ability to establish the shelf life of such a product. The need to be precise in terms of how to quantify the active components of non-viable cells was essential to his criticism of ISAPP’s definition of postbiotics. Prof. Morelli concluded that researchers must address this issue of quantification methods, both to advance research and to provide regulatory bodies needed approaches to regulating non-viable microbes.

Conclusions from the debate were that the flaws of definitions previous to the ISAPP definition are apparent, and that the substance defined by ISAPP was useful to delineate, but that clear approaches to measurement of the active component(s) of non-viable microbes are needed to make the ISAPP definition workable in scientific and regulatory circles. The debate was very worthwhile, since science advances through respectful debates such as this.

It is clear that characterization of postbiotic products may be challenging, especially with increased complexity that arises by use of multiple inanimate strains, inclusion of  metabolic  endproducts, and the presence of whole and fragmented cells. But these challenges are not unique to postbiotics. Probiotic products can comprise complex mixtures of multiple strains as well as metabolic products (as the biomass during industrial production is harvested for freeze-drying, but not washed), along with significant amounts of non-viable microbes, which all may contribute to the overall health benefit. These facts are usually overlooked when relying just on viable cells for quantification.

Many commercial products carrying inanimate microbes and metabolic fermentation products, that potentially fit the ISAPP definition of postbiotics, are already available in the market. These are diverse products such as a mixture of two lactobacilli aimed at treating infant and adult diarrhea3 or a fermented infant formula to support pediatric growth4. Similar products also target animal nutrition5. A tightly controlled manufacturing process may be the path forward to warrant reproducibility of health benefits. Suitable characterization methodologies such as flow cytometry for non-viable microbes and mass spectrometry for metabolites seem to be relevant to sufficient postbiotic product characterization.

In brief, the ISAPP definition itself seemed well accepted by the meeting participants, but concerns were raised about how to quantify postbiotics according to the definition. We intend to address this point through consultations with experts, proposing scientific paths to help conceptualize factors that need to be considered for postbiotic quantification.

Picture of panelists on stage with conference participants in the audience

Panel debate about ISAPP’s definition of postbiotics held at Beneficial Microbes conference in Amsterdam on November 14th, 2022. On the stage, from left to right: Koen Venema (conference chair), Gabriel Vinderola, Seppo Salminen, Guus Roeselers and Lorenzo Morelli (on screen).

References

  1. Tsilingiri, K. & Rescigno, M. Postbiotics: What else? Benef. Microbes (2013) doi:10.3920/BM2012.0046.
  2. Salminen, S. et al. The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nat. Rev. Gastroenterol. Hepatol. (2021) doi:10.1038/s41575-021-00440-6.
  3. Malagón-Rojas, J. N., Mantziari, A., Salminen, S. & Szajewska, H. Postbiotics for Preventing and Treating Common Infectious Diseases in Children: A Systematic Review. Nutrients 12, (2020).
  4. Béghin, L. et al. Fermented infant formula (with Bifidobacterium breve C50 and Streptococcus thermophilus O65) with prebiotic oligosaccharides is safe and modulates the gut microbiota towards a microbiota closer to that of breastfed infants. Clin. Nutr. 40, 778–787 (2021).
  5. Kaufman, J. D. et al. A postbiotic from Aspergillus oryzae attenuates the impact of heat stress in ectothermic and endothermic organisms. Sci. Rep. 11, 6407 (2021).

Additional reading:

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

Postbiotics: The concept and their use in healthy populations

 

Watch / listen to the debate here: https://youtu.be/pATNfhQY4P4

 

 

Human milk oligosaccharides as prebiotics to be discussed in upcoming ISAPP webinar

/in Consumer Blog, ISAPP Science Blog /by KC

Human milk oligosaccharides (HMOs), non-digestible carbohydrates found in breast milk, have beneficial effects on infant health by acting as substrates for immune-modulating bacteria in the intestinal tract. The past several years have brought an increase in our understanding of how HMOs confer health benefits, prompting the inclusion of synthetic HMOs in some infant formula products.

These topics will be covered in an upcoming webinar, “Human milk oligosaccharides: Prebiotics in a class of their own?”, with a presentation by Ardythe Morrow PhD, Professor of Pediatrics, Cincinnati Children’s Hospital Medical Center, University of Cincinnati College of Medicine. The webinar will provide an overview of what HMOs are, how they are breaking new ground with the types of health benefits they can provide to infants and the recent technological innovations that will facilitate their translation into new infant formulas.

Dr. Karen Scott, Rowett Institute, University of Aberdeen, and Dr. Margriet Schoterman, FrieslandCampina, will host the webinar. All are welcome to join this webinar, scheduled for Wednesday, Oct 19th, 2022, from 10-11 AM Eastern Daylight Time.

Registration is now closed. Please watch the recording of this webinar below.

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.

 

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

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

/in ISAPP Science Blog, Consumer Blog /by KC

The past two decades have brought a massive increase in knowledge about the human gut microbiota and its links to human health through diet. And although many people perceive that regular consumption of safe, live microbes will benefit their health, the scientific evidence to date has not been sufficiently developed to justify adding a daily recommended intake of live microbes to food guides for different populations.

Recently, a group of seven scientists, including six ISAPP board members, published their perspective about the value of establishing the link between live dietary microbes and health. They conclude that although the scientific community has a long way to go to build the evidence base, efforts to do this are worthwhile.

The collaboration on this review was rooted in an ISAPP expert discussion group held at the 2019 annual meeting in Antwerp, Belgium. During the discussion, various experts presented evidence from their fields—addressing the potential health benefits of live microbes in general, rather than the narrow group of microbial strains that qualify as probiotics.

Below, the authors of this new review answer questions about their efforts to quantify the relationship between greater consumption of live microbes and human health.

Why is it interesting to look at the potential importance of live microbes in nutrition?

Prof. Joanne Slavin, PhD, RD, University of Minnesota

Current recommendations for fiber intake are based on protection against cardiovascular disease—so can we do something similar for live microbes? We know that intake of live microbes is thought to be health promoting, but actual recommended intakes for live microbes are missing.  Bringing together a talented group of microbiologists, epidemiologists, nutritionists, and food policy experts moves this agenda forward.

Humans need proper nutrition to survive, and a lack of certain nutrients creates a ‘deficiency state’. Is this the case for live microbes?

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

I don’t think we’ll find that live microbes are essential in the same way that vitamins and minerals lead to deficiency diseases. After all, gnotobiotic animal colonies are viable. But I believe there is enough evidence to suggest that consumption of live microbes will promote health. Exactly how and to what extent remains to be established.

Why think about intake of ‘live microbes’ in general, rather than intake of probiotic & fermented foods specifically?

Prof. Maria Marco, PhD, University of California Davis

We are constantly exposed to microorganisms in our foods and beverages, in the air, and on the things we touch. While much of our attention has been on the microbes that can cause harm, most of our microbial exposures may not affect us at all or, quite the opposite, be beneficial for maintaining and improving health. Research on probiotic intake as a whole supports this possibility. However, probiotic-containing foods and dietary supplements are only a part of our dietary connection with live microbes. Non-pasteurized fermented foods (such as kimchi and yogurts) can contain large numbers of non-harmful bacteria (>10^7 cells/g). Fruits and vegetables are also sources of living microbes when eaten raw.  Although those raw foods they may contain lower numbers of microbes, they may be more frequently eaten and consumed in larger quantities. Therefore, our proposal is that we take a holistic view of our diets when weighing the potential significance of live microbe intake on health and well-being.

What are dietary sources of live microbes? And do we get microbes in foods besides fermented & probiotic foods?

Prof. Bob Hutkins, PhD, University of Nebraska Lincoln

For tens of thousands of years, humans consumed large amounts of microbes nearly every time they ate food or drank liquids. Milk, for example, would have been unheated and held at ambient temperature with minimal sanitation and exposed to all sorts of microbial environments.  Thus, a cup of this milk could easily have contained millions of bacteria. Other foods like fruits and vegetables that were also exposed to natural conditions could have also contained similar levels of microbes. Even water would have contributed high numbers of live microbes.

Thanks to advances in food processing, hygiene, and sanitation, the contemporary western diet generally contains low levels of microbes. Consider how many foods we eat that are canned, pasteurized, or cooked – those foods will contain few, in any live microbes. Fresh produce can serve as a source of live microbes, but washing, and certainly cooking, will reduce those levels.

For sure, the most reliable sources of dietary microbes are fermented foods and beverages. Even if a fresh lettuce salad were to contribute a million bacteria, a single teaspoon of yogurt could contain 100 times more live bacteria. Other popular fermented foods like kefir, kimchi, kombucha, and miso, can contain a large and relatively diverse assortment of live microbes. Other fermented foods, such as cheese and sausage, are also potential sources, but the levels will depend on manufacturing and aging conditions. Many fermented, as well as non-fermented foods are also supplemented with probiotics, often at very high levels.

What’s the evidence that a greater intake of live microbes may lead to health benefits?

Prof. Dan Merenstein, MD, Georgetown University

Studies have shown that fermented foods are linked to a reduced risk of cardiovascular disease, reduced risk of weight gain, reduced risk of type 2 diabetes, healthier metabolic profiles (blood lipids, blood glucose, blood pressure and insulin resistance), and altered immune responses. This link is generally from associative studies on certain fermented foods. Many randomized controlled trials on specific live microbes (probiotics and probiotic fermented foods) showing health benefits have been conducted, but randomized controlled trials on traditional fermented foods (such as kimchi, sauerkraut, kombucha) are rare. Further, no studies have aimed to assess the specific contribution of safe, live microbes in diets as a whole on health outcomes.

Why is it difficult to interpret past data on people’s intake of live microbes and their health?

Prof. Colin Hill, PhD, University College Cork

It would be wonderful if there were a simple equation linking the past intake of microbes in the diet and the health status of an individual (# MICROBES x FOOD TYPE = HEALTH). In reality, this is a very complex challenge. Microbes are the most diverse biological entities on earth, our consumption of microbes has not been deliberately recorded and can only be estimated, and even the concept of health has defied precise definitions for centuries. To further confuse the situation microbes meet the host in the gastrointestinal tract, the site of our enormously complex mucosal immune system and equally complex microbiome.  But the complexity of the problem should not prevent us from looking for prima facie evidence as to whether or not such a relationship is likely to exist.

Databases of dietary information have data on people’s intake of live microbes, but what are the limitations of our available datasets?

Prof. Dan Tancredi, PhD, University of California Davis

Surveys often rely on food frequency questionnaires or diaries to determine consumption of specific foods. These are notoriously prone to recall error and/or other types of measurement error. So, even just measuring consumption of foods is difficult. For researchers seeking to quantify survey respondents’ consumption of live microbes, these challenges become further aggravated because the respondents would not typically know the microbial content in the foods they consumed. Instead, we would have to have them tell us the types and amounts of the foods they ate, and then we would need to translate that into approximate microbial counts—but even within a particular food, the microbial content can vary, depending on how it was processed, stored, and/or prepared prior to consumption.

See ISAPP’s press release on this paper here.

Current status of research on probiotic and prebiotic mechanisms of action

/in ISAPP Science Blog /by KC

By Mary Ellen Sanders, PhD, ISAPP Executive Science Officer

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

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

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

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

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

Prebiotic benefits and mechanisms of action

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

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

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

Probiotic health effects and mechanisms of action

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

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

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

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

See here to watch the webinar in full.

 

 

ISAPP partners with British Nutrition Foundation for fermented foods webinar

/in Consumer Blog, News /by KC

Did you miss the live webinar? Access the archived version here. Read the speaker Q&A here.

From sourdough starter tips to kombucha flavor combinations – if you’ve checked a social media feed lately, you’ll know how many people are sharing an interest in fermented foods as they self-isolate during the pandemic. And with this rise in popularity comes a host of questions about the practice and the science of fermented foods.

To meet the need for science-based information about fermented foods, ISAPP has partnered with the British Nutrition Foundation (BNF) on a free webinar titled ‘Fermented Food – Separating Hype from Facts.’ The BNF is a UK-based registered charity that brings evidence-based information on food and nutrition to all sectors, from academia to medicine.

The webinar, designed for practicing dietitians and nutrition-savvy members of the public, featured three leading scientific experts who explained the microbiology of fermented foods, the evidence for their health effects, and who might benefit from making these foods a regular part of the diet. Viewers will come away with a clear understanding of what fermented foods are and what evidence exists for their health benefits.

The webinar was held live on Wednesday, July 1, 2020 from 1pm-2pm (BST).

Webinar speakers & topics

 Understanding fermented foods: Dr. Robert Hutkins, University of Nebraska, USA

Exploring the evidence for effects of fermented foods on gastrointestinal health – how strong is it? Dr. Eirini Dimidi, Kings College London

What role can fermented foods have in our diet? A public health perspective, Anne de la Hunty, British Nutrition Foundation

For a quick primer on fermented foods, see the short ISAPP video here or the ISAPP infographic here.

Is probiotic colonization essential?

/in Consumer Blog, ISAPP Science Blog /by KC

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

It is increasingly appreciated by consumers, physicians, and researchers alike that the human digestive tract is colonized by trillions of bacteria and many of those bacterial colonists have important roles in promoting human health. Because of this association between the gut microbiota and health, it seems appropriate to suggest that probiotics consumed in foods, beverages, or dietary supplements should also colonize the human digestive tract. But do probiotics really colonize? What is meant by the term “colonization” in the first place? If probiotics don’t colonize, does that mean that they are ineffective? In that case, should we be searching for new probiotic strains that have colonization potential?

My answer to the first question is no – probiotics generally do not colonize the digestive tract or other sites on the human body. Before leaping to conclusions on what this means for probiotic efficacy, “colonization” as defined here means the permanent, or at least long-term (weeks, months, or years) establishment at a specific body site. Colonization can also result in engraftment with consequential changes to the gut microbiota composition and function. For colonization to occur, the probiotic should multiply and form a stably replicating population. This outcome is distinct from a more transient, short-term (a few days to a week or so) persistence of a probiotic. For transient probiotics, it has been shown in numerous ways that they are metabolically active in the intestine and might even grow and divide. However, they are not expected to replicate to high numbers or displace members of the native gut microbiota.

Although some studies have shown that digestive tracts of infants can be colonized by probiotics (weeks to months), the intestinal persistence times of probiotic strains in children and adults is generally much shorter, lasting only few days. This difference is likely due to the resident gut microbiota that develops during infancy and tends to remain relatively stable throughout adulthood. Even with perturbations caused by antibiotics or foodborne illness, the gut microbiome tends to be resilient to the long-term establishment of exogenous bacterial strains. In instances where probiotic colonization or long-term persistence was found, colonization potential has been attributed more permissive gut microbiomes specific to certain individuals. In either case, for colonization to occur, any introduced probiotic has to overcome the significant ecological constraints inherent to existing, stable ecosystems.

Photo by http://benvandenbroecke.be/ Copyright, ISAPP 2019.

This leads to the next question: Can probiotics confer health benefits even if they do not colonize? My answer is definitely yes! Human studies on probiotics with positive outcomes have not relied on intestinal colonization by those microbes to cause an effect. Instead of colonizing, probiotics can alter the digestive tract in other ways such as by producing metabolites that modulate the activity of the gut microbiota or stimulate the intestinal epithelium directly. These effects could happen even on short-time scales, ranging from minutes to hours.

Should we be searching for new probiotic strains that have greater colonization potential? By extension of what we know about the resident human gut microbiota, it is increasingly attractive to identify bacteria that colonize the human digestive tract in the same way. In some situations, colonization might be preferred or even essential to impacting health, such as by engrafting a microbe that performs critical metabolic functions in the gut (e.g. break down complex carbohydrates). However, colonization also comes with risks of unintended consequences and the loss of ability to control the dose, frequency, and duration of exposure to that particular microbe.

Just as most pharmaceutical drugs have a transient impact on the human body, why should we expect more from probiotics? Many medications need to be taken life-long in order manage chronic conditions. Single or even repeated doses of any medication are similarly not expected to cure disease. Therefore, we should not assume a priori that any observed variations in probiotic efficacy are due to a lack of colonization. To the contrary, the consumption of probiotics could be sufficient for a ripple effect in the intestine, subtly altering the responses of the gut microbiome and intestinal epithelium in ways that are amplified throughout the body. Instead of aiming for engraftment directly or hand-wringing due to a lack of colonization, understanding the precise molecular interactions and cause/effect consequences of probiotic introduction will lead to a path that ultimately determines whether colonization is needed or just a distraction.

blog post resilience figure 1

Resilience as a measure of health: implications for health claims for foods

/in featured, ISAPP Science Blog /by Mary Ellen Sanders

January 16, 2018. By Mary Ellen Sanders PhD, Sylvie Binda PhD, Seppo Salminen PhD, Karen Scott PhD

Demonstrating health benefits for healthy people is a challenge faced by those attempting to communicate claims on a health promoting food. Foods, in many global regulatory frameworks, are intended for the general population. Therefore, any benefits ascribed to them, the logic goes, must be demonstrated in the generally healthy population.

An old concept has new-found notoriety in the context of offering an approach for establishing health benefits for healthy people. It is the concept of resilience. In an ecological sense, resilience refers to the ability of an ecosystem to withstand perturbation and continue normal function, i.e. maintain homeostasis. In the context of human physiology, resilience enables a host to remain healthy even when exposed to a stress, or to recover from a stress faster. A variety of external challenges such as drugs, pathogens, emotional stress, poor diet among others, may perturb normal physiological function or disrupt the gut ecosystem. Individuals more able to maintain stability of physiological functions when exposed to such challenges would be healthier than those who cannot maintain stability.  Thus, a food would be considered to have a beneficial effect if it could increase the resilience of the consumer to a challenge.

This concept was described in an EFSA guidance document on biological relevance of data in scientific assessments:

“When subject to a disturbance, a biological system enters in a transient state: a process variable has been changed and the system has not yet reached steady state. Some systems, including humans, have the capacity to regulate their internal environment and to maintain a stable, relatively constant condition of properties; it is called ‘homeostatic capacity’. Resilience represents the amount of disturbance that can be absorbed by a system before the system changes or loses its normal function, or the time taken to return to a stable state, within the normal operation range following the disturbance…” [Reducing] “homeostatic capacity … might be detrimental, whereas increasing the capacity could be beneficial.”

This concept aligns with the definition of ‘health’, which includes the ability to adapt to the environment.

Resilience of gut microbiota

This concept of resilience can be applied to the human microbiota as an ecosystem. Once established in early childhood, our colonizing microbiota reaches a relatively stable state. Although brief fluctuations occur, especially in relation to daily diet and medicines used, the microbial ecosystem of a healthy adult provides relatively stable functionality.  Disruption of the microbiota by repeated stressors can be associated with poorer health. There seems to be a solid rationale that the ability of the colonizing microbiota to resist, or recover quickly from, perturbations reflects a person’s ability to remain healthy. The microbiota stability may be indicated in either populations of bacteria or their metabolic output.

Homeostasis and health: a statistical approach

“A statistical approach to measuring improved health was proposed by Dr. Dan Tancredi at the 2010 ISAPP meeting. It is reprinted here from: Sanders, et al. 2011. Health claims substantiation for probiotic and prebiotic products. Gut Microbes 2:3, 1-7.

An approach to measuring improved health may be to measure homeostasis, as suggested by D. Tancredi. From a statistical point of view, if an intervention were able to minimize the variation around the mean for a specific measure (even in the absence of changing the mean; Fig. 1), it could be a reflection of improved health, assuming a biological rationale exists that tighter control of the parameter is physiologically advantageous. In other words, lessening the fluctuation around an individual’s biomarker could be interpreted as contributing to improving health. This novel idea emphasizes the importance of homeostasis as a focus of studies on health, and provides a rationale based in solid statistical theory as a way to measure this.

One challenge to demonstrating the value of this approach is to identify appropriate biomarkers that could be studied. The following properties would be important to a relevant biomarker for homeostasis:

blog resilience figure one

  • maintaining moderate levels of the biomarker is associated with good health;
  • high or low values are associated with ill health;
  • biomarker levels in the same person can fluctuate over time; and
  • reducing the magnitude or duration of such fluctuations in healthy people is considered desirable (Fig. 2).

Such a biomarker could be an individual endpoint or be formed as a ratio of two other biomarkers, when maintaining the same relative amounts of the two component biomarkers would be desirable.

Assuming a biomarker with the above properties is available, it could be used as the outcome measure in a randomized controlled trial to provide evidence that the experimental food is able to improve the maintenance of health in humans. Statistically, the trial would be set up to address the hypothesis that the experimental substance is associated with lower variation in biomarker levels, compared to the control arm, in subjects who were healthy at baseline. Such a trial would be able to use information on within-person variations in biomarker levels, even those who did not become ill. Partly as a result of the more efficient use of study data, such a trial would require far fewer subjects than an intervention that instead addressed the hypothesis that treatment is associated with fewer healthy persons becoming ill.

A mounting understanding of the value of stability of the colonizing microbial communities makes this endpoint an attractive one to consider. Perturbation of gut microbiota is associated with intestinal dysfunction, as illustrated during antibiotic treatment. Specific probiotics have been shown to promote a quicker rebound from antibiotic-induced microbiota disruption, including a study on Lactobacillus rhamnosus GG (LGG) (Cox et al. 2000). This paper concludes ‘…that a key mechanism for the protective effect of LGG supplementation on the subsequent development of allergic disease is through the promotion of a stable, even and functionally redundant infant gastrointestinal community.’

However, it would be useful to define additional biomarkers that would be appropriate targets for this type of investigation.

In pediatric nutrition, the measurement of metabolic homeostasis has become a standard approach when developing infant formulas (Heird, 2005).  The concept of homeostasis as a model to distinguish between foods (including food supplements) and medicinal products was explored by the Council of Europe (2011), and is an interesting correlate to the above hypothesis.”

Conclusions

The recent recognition by EFSA that maintenance of homeostasis is a valid measure of health provides an opportunity to apply this concept to validate health benefits of specific foods and food ingredients. Stability of microbial populations, microbial metabolism or host physiological readouts could be measured to reflect the concept of resilience. Since there is no definitive composition of a ‘healthy human microbiota’, a more reasonable target for measuring positive impacts of a probiotic on the microbiota would be reflected not in absolute levels of specific microbes but in the ability of a specific probiotic or prebiotic to bolster the resilience of the microbiota.

 

References:

Council of Europe. Homeostasis, a model to distinguish between foods (including nutritional supplements) and medicinal products 2008; (Accessed February 24, 2011, at http://www.coe.int/t/e/social_cohesion/soc-sp/homeostasis%20%282%29.pdf ).

Cox MJ, Huang YJ, Fujimura KE, Liu JT, McKean M, Boushey HA, et al. Lactobacillus casei abundance is associated with profound shifts in theGunderson LH, 2000. Ecological resilience: in theory and application. Annual Review of Ecology and Systematics, 31, 425–439.

EFSA guidance document:  Guidance on the assessment of the biological relevance of data in scientific assessments; July 12, 2017; EFSA Journal 2017;15(8):4970

Heird WC. Biochemical homeostasis and body growth are reliable end points in clinical nutrition trials. Proceedings of the Nutrition Society 2005; 64:297-303.

Huber M, Knottnerus JA, Green L, van der Horst H, Jadad AR, Kromhout D, Leonard B, Lorig K, Loureiro MI, van der Meer JW, Schnabel P, Smith R, van Weel C, Smid H (2011). “How should we define health?” BMJ. 343:d4163.

Sanders, et al. 2011. Health claims substantiation for probiotic and prebiotic products. Gut Microbes 2:3, 1-7; May/June 2011