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Pasteurized Akkermansia muciniphila as a postbiotic: EFSA approval and beyond

/in ISAPP Science Blog /by KC

By Prof. Seppo Salminen, University of Turku, Finland

Earlier this year, the European Food Safety Authority (EFSA) delivered an opinion that heat-treated Akkermansia muciniphila is safe for use as a novel food in the European Union. EFSA described A. muciniphila as a “well‐characterised non‐toxin producing, avirulent microorganism that has been reported as part of normal gut microbiota” and determined based on a literature review that its safety is adequate for use as a food supplement or in foods for special medical purposes, at a specified maximum dose.

ISAPP connected with three individuals from A-Mansia Biotech, the company that initiated the EFSA request: Prof. Willem M. de Vos and Prof. Patrice D. Cani, as well as the company CEO Michael Oredsson. They jointly answered some questions on their EFSA success and plans for the future.

Originally, what led you to test whether the pasteurized form of the live microbe might be able to confer a health benefit?

We first noticed that killing Akkermansia by using autoclaving (121°C 20°C) completely abolished the beneficial effects of Akkermansia. However, we wanted to test whether a milder procedure (i.e. pasteurization) could keep some structures of the outer membrane of Akkermansia intact and therefore still able to interact with the host. We knew that several other classical probiotics (types of lactobacilli) partly retained their effects after pasteurization. Our surprise was to see that pasteurization successfully maintained the effects of Akkermansia compared to the live form, but even increased its efficacy.

Pasteurised Akkermansia has now been extensively studied for safety and health effects. Does this make it the first real postbiotic, as defined by ISAPP?

If we are accepting the ISAPP definition proposed in 2021, we can answer yes to this question. Prof. Cani in his scientific capacity believes indeed that the product (pasteurized Akkermansia) is unique and can fall under this definition. Whether A-Mansia will be positioning the pasteurized Akkermansia as a postbiotic according to that definition is still to be discussed.

Pasteurised Akkermansia has been demonstrated to control gut barrier and reduce inflammation associated with fat storage and obesity – will we see a product that helps in weight loss/control?

Akkermansia is clearly playing a major role by tackling the gut barrier dysfunction which is the root cause of the different metabolic problems mentioned here (i.e., inflammation, fat storage, liver/fat tissue inflammation) and they are all connected to better energy expenditure/oxidation when a lower inflammation/insulin resistance is observed. Therefore, pasteurized Akkermansia should help to maintain a healthy weight and abdominal fat. A product focusing on a better weight management is currently under development at A-Mansia.

Is the next step to apply for an EU health claim?

All the current human investigations and studies at our company are aiming at fulfilling future EU health claims.

It took two years to get the acceptance for the safety of inanimate pasteurised Akkermansia – what do you think of this timeframe for safety assessment?

This is perfectly in line with what the EFSA was expecting, although it was a few months delayed with the COVID-19 crisis. The assessment was very clear, smooth and well managed by the EFSA.

In general, what do you think the future holds for postbiotics as food ingredients?

We are entering into a new era, first with next-generation beneficial bacteria, and Akkermansia as one of the most studied (if not the most studied). The pasteurized form is so active, stable, and easy to use that the postbiotic era, as led by this example, is a novel and innovative manner of targeting the microbiome for improving/maintaining health.

 

As the science on health benefits for similar postbiotic substances continues to advance, we may see more ingredients qualifying as true postbiotics. More products are likely to follow a similar path, considering the practical advantages of delivering non-living substances to consumers.

 

What do we mean by ‘conferring a health benefit on the host’?

/in Consumer Blog, ISAPP Science Blog /by KC

By Prof. Colin Hill, University College Cork, Ireland

Four of the Consensus definitions produced by ISAPP in recent years (see 1-4 below) finish with a similar wording, insisting that probiotics, prebiotics, synbiotics and postbiotics must “confer a health benefit on the host”. This proviso was included to explicitly reinforce the fact that the raison d’etre for these interventions is that they must demonstrably improve host health. It would perhaps be wise to just stop there and leave the interpretation of what this really means to each individual reader. But that would not make for a very long blog and I am not very wise. Furthermore, it is useful to be more precise for scientific and regulatory purposes. At least two aspects seem to be open to elaboration; what is meant by ‘host’ and what is a ‘health benefit’? I will base my thoughts on the probiotic definition, but the logic should apply equally to all four health-based definitions.

Host. According to the Google dictionary a host is ‘an animal or plant on or in which a parasite or commensal organism lives’. This means there are millions of potential host species on our planet, something that could potentially create confusion. For example, if a well characterised microbe (or microbes) is shown to provide a measurable health benefit when administered in adequate amounts in a murine model (the host) then it clearly meets the stated definition of probiotic. But only for mice! It should not be referred to as a probiotic for other species, including humans, solely based on murine evidence. This creates a situation where the same microbe can clearly meet the criteria to be a probiotic for one host but not for another. This is not simply semantics; it is of vital importance that it should not be assumed that health benefits confirmed in one host will also be realised in another without supporting evidence. Since the majority of discussions of probiotics address human applications, it may serve all stakeholders well – even if not directly mandated by the definition – if the word ‘probiotic’ was only used without qualification for microbes with measurable benefits in humans while all others should be qualified with the target host; ‘equine probiotic’, ‘canine probiotic’, or even ‘plant probiotic’.

Health benefit. Health is of course a continuum from a desirable but almost certainly unattainable state where every organ is performing optimally (something I will term ‘ideal health’) to a point where death is imminent (that I will term ‘poor health’). Of course, health is multidimensional and far more complex than a straight line between ‘ideal’ and ‘poor’ but for simplicity I will treat it as such. If we place ideal health on the left end of our straight line and poor health at the right end, then obviously any shift towards the left can be considered a health benefit. It could even be reasonably argued that if someone is gradually progressing from left to right down our imaginary line (for example, as we age) then halting or slowing down that progression could also be considered a health benefit. From this perspective every individual (not just the unwell) could potentially derive a health benefit from a probiotic, prebiotic, synbiotic or postbiotic.

The issue of cosmetic benefits is more nuanced. If an intervention improves someone’s appearance (or reduces body odour for example) it might not be considered a health benefit per se, but of course it could well have a beneficial effect on an individuals’ mental health. I will leave it to the psychologists and psychiatrists to determine how this could be convincingly demonstrated.

There is also the issue of production characteristics where the host is a food animal or a crop. If a microbial-based intervention leads to faster growth rates and increased yields should this qualify as a health benefit? My own opinion is if the intervention leads to higher productivity by preventing infections it could be considered a health benefit, but not if it simply leads to faster growth rates by improving feed conversion for example.

Can changing the microbiome be considered a health benefit? A trickier question is whether a direct effect on the microbiome could be considered as a health benefit? Every host has a microbiome of a particular configuration, richness, and diversity. I don’t think we are yet at a point where measurable changes in these general indices of microbiome composition can be termed a health benefit in the absence of a link to a more established health outcome. The consequence of any change will be microbiome-specific in any event; a reduction in diversity in the vaginal microbiome might be desirable, whereas an increase in diversity in the gut microbiome might well be considered beneficial. But what if we can measure a reproducible reduction in a specific pathobiont like Clostridioides difficile, or an increase in a microbe that is associated with good health such as Bifidobacterium? In my opinion we are arriving at a point where we can begin to refer to these impacts as a health benefit. This will become more and more relevant as we establish direct causal links between individual commensal microbes and health outcomes. Equally, an intervention that preserves microbiome structure during a disruption (e.g. infection or antibiotic treatment) could also be considered as beneficial. I don’t know if regulators are yet at the point of accepting outcomes such as these as direct health benefits, but I believe a strong case can be made.

To finish, I believe that it is a very exciting time for all of us in the field of probiotics, prebiotics, synbiotics and postbiotics, but it is really important that all of this important science is not compromised by loose language or by literal interpretations that adhere to the letter of the definitions but not to the intent. If you want to fully understand the intent of the definitions, I encourage you to read the full text of the consensus papers.

 

  1. https://doi.org/10.1038/nrgastro.2014.66
  2. https://doi.org/10.1038/nrgastro.2017.75
  3. https://doi.org/10.1038/s41575-020-0344-2
  4. https://doi.org/10.1038/s41575-021-00440-6

A postbiotic is not simply a dead probiotic

/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

Postbiotics, recently addressed in an ISAPP consensus panel paper, are defined as a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host. Criteria to meet the postbiotic definition are summarized here. One noteworthy aspect of this definition is that the word ‘probiotic’ does not appear. Although in practice a probiotic strain may be used as a progenitor strain in the manufacture of a postbiotic, the simple process of inactivating a probiotic is not sufficient to be called a postbiotic. It cannot be assumed that any non-viable probiotic cells in a probiotic product are automatically considered a postbiotic component. If a probiotic strain is used as a progenitor of a postbiotic, an efficacy study must be redone using the inanimate preparation and a benefit must be demonstrated. A probiotic product displaying fewer than the labeled count of viable cells is merely a low-quality product; it is not a postbiotic.

Further, the ISAPP consensus definition on postbiotics recognizes that the process of making a postbiotic implies a deliberate step to inactivate the viable cells of the progenitor strain. This process can be achieved by different technological steps such as heat-treatment (perhaps the most feasible approach), high pressure, radiation or simply aerobic exposure for strict anaerobes. A corresponding efficacy study must be conducted on the preparation. Or at the very least, any postbiotic component of a probiotic product must be specifically shown to contribute to the health benefit conferred by the product.

In contrast to postbiotics, probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Four minimum criteria should be met for a strain to be considered as a probiotic: (i) sufficiently characterized; (ii) safe for the intended use; (iii) supported by at least one positive human clinical trial conducted according to generally accepted scientific standards or as per recommendations and provisions of local/national authorities when applicable; and (iv) alive in the product at an efficacious dose throughout shelf life (Binda et al. 2020). This last requirement reflects the key difference between probiotics and postbiotics. Probiotics must deliver an efficacious number of viable cells through the shelf life of the product. In practice, probiotic products may display significant numbers of non-viable cells (Raymond & Champagne, 2015), as some cells may lose viability during the technological process of biomass production, while undergoing manufacture or preservation steps and through product storage prior to purchase. In order to provide the target dose until end of shelf life, an overage of 0.5 to 1 log order CFU above the expected counts of viable cells is commonly included in the product to compensate for potential losses during product storage and handling (Fenster et al. 2019).

Thus, some quantity of non-viable cells may be usually expected in certain probiotic products, especially supplement products claiming a long, room temperature stable shelf-life. However, they will be considered as probiotic products of quality as long as they are able to deliver the expected amount of viable cells until the end of the product shelf-life. It is worth mentioning that the probiotics are expected to be viable at the moment of their administration. After that, if exposure to different regions of the gut causes cells to die, it is not of consequence as long as a health effect is achieved.

Probiotics and postbiotics have things in common (the need of efficacy studies that demonstrates their benefits) and things that distinguish them (the former are administered alive, whereas the latter are administrated in their inanimate form), but no probiotic becomes a postbiotic just by losing cell viability during storage.

live-dead-probiotics

Dead bacteria – despite potential for benefit – are not probiotics

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

Re-posted from an original blog article by Dr. Mary Ellen Sanders, ISAPP Executive Science Officer

At the 2018 International Scientific Association of Probiotics and Prebiotics (ISAPP) meeting in Singapore, two renowned speakers reported unpublished research documenting the health benefits of dead bacteria.

Prof. Hill showed that an inactivated Lactobacillus strain reduced anxious behavior, reduced cortisol levels, and impacted the microbiome in a mouse model. Prof. Patrice Cani showed that heat-killed Akkermansia muciniphila were sufficient to ameliorate obesity and diabetes in mice. Both professors made the point that these microbial preparations were not probiotics.

Prof. Colin Hill is the lead author on the oft-cited and -downloaded (over 40,000 times) ISAPP consensus paper reaffirming the definition of probiotics, which emphasizes that probiotics must be alive when administered. This, of course, does not preclude health effects of dead bacteria. One just must remember that dead bacteria are NOT probiotics. Many different types of microbe-derived substances such as metabolites, cell wall fragments, enzymes, and neurochemicals, can have beneficial physiological effects. A 2016 review by de Almada et al. lists a couple dozen published studies of physiologically active dead bacteria.

Preserving the long-accepted definition of probiotics as ‘live microbes’ is important to the many stakeholders involved in the field. Consumers should be able to purchase a product labeled as ‘probiotic’ and know that it contains an effective level of live microbes. Regulators should know that a product without an adequate level of live microbes is fraudulent if called a probiotic. Scientists should be able to use the term and have reviewers and readers understand that they are referring to functions of live microbes. An agreed-upon definition enables us to be precise when discussing an issue. Saying that because dead bacteria have a health effect and they should be called ‘probiotics’ is like saying that because vitamin D has a health benefit, the term ‘vitamin A’ should include vitamin D.

What are implications of the fact that dead microbes may have health effects?

Stewards of the probiotic field can expect increased frustration with popular press writers. I’ll use a recent example to make this point. The June 2018 Cooking Light Magazine /Special Gut Health Issue included an article that lists sourdough bread as a top probiotic-containing fermented food. When the error about misusing the term ‘probiotic’ to describe a food that contained no live probiotic bacteria was pointed out to the editor by Jo Ann Hattner, MPH RD author of Gut Insight, Cooking Light chose to ignore advice from an expert and justify their mistake by using an irrelevant observation that both live and dead cells in probiotic products may generate beneficial biological responses. Apparently, the expertise she derived from a paper that described the “probiotic paradox” trumped the considered opinions of global expert scientists/researchers and the FAO/WHO, who agree that probiotics must be alive when administered. It’s quite a simple concept. It is true that some dead microbes may have some health benefit (although evidence of such an effect is much lower than that available from controlled human trials on actual probiotics), but they are NOT probiotics.

Confusion. Some audiences will be confused by the idea that probiotics that are killed can have health benefits. Inaccurate writers, such as the Cooking Light author above, will perpetuate this error. This is unfortunate, since the probiotic concept is a long-standing one, backed by much mechanistic and clinical evidence. Conflating probiotics with dead bacteria will lead to confusion over important aspects of an effective probiotic product.

Overages.  It is not uncommon for commercial products to be formulated with live microbes at time of manufacture that far exceed the number claimed on the label. This is to assure that the product meets label claim at the end of shelf life, as probiotics often die to some extent during storage. Sometimes this ‘overage’ can reach 10-fold more than the level guaranteed on the product, although more typically it’s 2- to 5-fold. If over the course of shelf life the viable count drops to label claim, then dead microbes may comprise as much as 90% of the microbes present. We don’t know if these dead bacteria – although no longer probiotics – have physiological benefits, as no studies have been conducted on this form of inactivated cells, but it’s an interesting possibility. When we study a probiotic product, perhaps that product needs to be characterized by both the level of live and dead microbes that are present. Means of inactivation, such as heat, pressure, irradiation, or sonication, may impact the physiological activity of the resulting dead cells.

Opportunity.  Keeping probiotics alive in commercial products is a challenge. Research such as Prof. Cani’s targets an expanded range of microbes – many isolated from the human GI tract – that cannot be easily grown and stabilized in commercial products. Further, these microbes lack the history of safe use that food-associated microbes have, and so administration of high numbers of these next-generation probiotics will require proof of safety. If these microbes can be killed and still deliver health benefits, the commercialization process could be simplified.

ISAPP may need to consider convening another consensus panel to address these newly emerging terms, such as postbiotic and paraprobiotic. Then we can all be on the same page when using these terms, which have important scientific, nutritional and clinical impact. Of course, even if ISAPP does this, authors may still choose to ignore it.