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Five things scientists should know about the future of probiotics and prebiotics

By Marla Cunningham​, Metagenics Global R&D Innovation Manager and 2021 ISAPP Industry Advisory Committee representative

As anyone connected with probiotics and prebiotics knows – there’s a lot happening in this space.

After a well-attended discussion group at the 2019 ISAPP Annual Meeting in Antwerp, a collaboration of 16 industry and academic scientists came together to produce a broad overview of current and emerging trends that were covered in this discussion. Just released online by Trends in Microbiology, the open access paper identifies some top trends across multiple spheres of influence on the future of probiotics and prebiotics.

  1. Discovery: Prebiotics and probiotics are emerging from unexpected sources – naturally occurring as well as synthesised or engineered. Food, human and animal microbiome-derived probiotics feature heavily in probiotic development through top-down microbiome data-driven approaches as well as physiological target-driven screening approaches. Prebiotic sources have expanded beyond traditional plant sources to include food waste streams, animal gut-derived glycans and mammalian milk as well as increasingly sophisticated synthesis techniques, involving sonication, high pressure, acid, enzyme and oxidation treatments. A growing understanding of the implications of carbohydrate structure on microbial metabolism is driving the emergence of designer prebiotics, as specific substrates for microbes of interest or the production of target metabolites, such as polyphenol-derived bioactives.
  2. Evaluation: Calls for integrated systems biology -omic approaches to the evaluation of probiotic and prebiotics effects continue to increase, utilising whole genome and metabolite approaches, with a focus on better understanding of mode of action as well as differential host and microbial responses that serve to improve host health.
  3. Product development: Quality assurance techniques continue to undergo evolution as the challenges of divergent product formats and increasingly complex formulations necessitate innovation in the field. There is a focus on techniques beyond cell culture enumeration for probiotic product verification as well as on the identification of functional markers of probiotic and prebiotic activity, which can be applied in complex food matrices.
  4. Regulation: Recent regulatory challenges with claim approval are understood to have driven corresponding evolution in clinical science and an increased focus on mechanistic elucidation. However, the converse is also occurring, with the development of novel probiotic species, therapeutics for disease treatment and increasingly microbiome-driven modes of action having implications for regulatory frameworks. This ‘give and take’ between science and regulatory requirements will likely accelerate into the future as the field continues to evolve.
  5. Implementation: Interest continues to grow in precision and personalised approaches to nutrition and healthcare, especially in the field of microbiome-related interventions where there is significant appreciation of host-to-host variability. The identification of putative microbial signatures of health and disease continues to fuel the development of health-associated microbes as candidate probiotics and as targets for novel prebiotic substrates. Further, a focus beyond microbial composition and into microbial function is driving interest in interventions which can correct metabolomic profiles, such as probiotics with specific enzyme activity to boost synthesis or catabolism of key microbial metabolites in vivo, including purine and monoamine compounds.

These and other trends create a rich and evolving landscape for scientists within the field and provide the promise of a bright future for prebiotics and probiotics.

Read the full paper here

Reference:

Cunningham, M., Azcarate-Peril, M. A., Barnard, A., Benoit, V., Grimaldi, R., Guyonnet, D., Holscher, H. D., Hunter, K., Manurung, S., Obis, D., Petrova, M. I., Steinert, R. E., Swanson, K. S., van Sinderen, D., Vulevic, J., & Gibson, G. R. (2021). Shaping the Future of Probiotics and Prebiotics. Trends in microbiology, S0966-842X(21)00005-6. Advance online publication. https://doi.org/10.1016/j.tim.2021.01.003

 

 

 

Current status of research on probiotic and prebiotic mechanisms of action

By Mary Ellen Sanders, PhD, ISAPP Executive Science Officer

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

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

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

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

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

Prebiotic benefits and mechanisms of action

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

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

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

Probiotic health effects and mechanisms of action

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

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

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

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

See here to watch the webinar in full.