The Science, Microbes & Health Podcast

This special year-end episode, which covers 2025’s highlights in biotic science, features three of the academic scientists who serve on the ISAPP board of directors: Prof. Maria Marco PhD from University of California, Davis (USA), Prof. Sarah Lebeer PhD from University of Antwerp (Belgium), and Dr. Gabriel Vinderola PhD from National University of Litoral (Argentina). After a brief review of ISAPP’s activities, the host, Prof. Colin Hill PhD from University College Cork (Ireland) asks the three guests about the talks that stood out from the ISAPP annual meeting. The guests cited talks by Prof. Howard Bauchner MD on publishing and the scientific communication ecosystem; Dr. Carolina Tropini PhD on factors affecting the gut microbial environment and engineering gut microbes as biosensors; and Dr. Peijun Tian PhD on a microbial metabolite that can signal to the brain to relieve depression through the gut-brain axis. The guests also described some stand-out papers published this year (linked below). Finally, they discussed how science is informing regulatory issues in different parts of the world, and shared some research from their own labs that they’re particularly excited about. Episode abbreviations and links: Paper from Dr. Peijun Tian PhD showing a microbial metabolite that signals through the gut-brain axis: Bifidobacteria with indole-3-lactic acid-producing capacity exhibit psychobiotic potential via reducing neuroinflammation NiMe diet paper: Cardiometabolic benefits of a non-industrialized-type diet are linked to gut microbiome modulation (also see this podcast episode) Paper on a host colonization factor in L. plantarum: A conserved bacterial genetic basis for commensal-host specificity Research presented at a congress this year on maternal feces given to infants: Eating a tiny bit of mom’s poop could give C-section babies an immune ‘primer’ Paper from Marco lab on microbial metabolites in sauerkraut: The fermented cabbage metabolome and its protection against cytokine-induced intestinal barrier disruption of Caco-2 monolayers

This episode features Prof. Yvan Vandenplas MD PhD from the University Hospital Brussels and Vrije Universiteit Brussel (Belgium), speaking about the science on probiotics and prebiotics in infant formula. Over the past 20 years in this field, awareness of the importance of the gastrointestinal microbiota has grown, and biotics have been employed to try to shape the gut microbiota of infants formula-fed to resemble that of breastfed infants. In particular, human milk oligosaccharides (HMOs) are prebiotics that are shown to change the microbiota composition, although the clinical benefits of these changes are not yet clear. What clinical benefits are achievable for infants who receive formula with added probiotics or prebiotics? Looking closely at the trials, it’s evident that probiotics and prebiotics are associated with a decrease in infections and antibiotic prescriptions, but researchers need to use these as primary endpoints in their trials to increase the strength of the evidence. In a recent European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) recommendations paper, the probiotic recommendations were challenging because for each specific probiotic intervention the group had difficulty finding two clinical trials with a similar design, limiting their ability to make conclusions. Prof. Vandenplas says more trials need to be done independently to strengthen the evidence. Long-term outcomes from probiotic or prebiotic supplementation in infant formula are possible as well, but much larger longitudinal trials are necessary to establish these outcomes. Episode abbreviations and links: ESPGHAN recommendations paper: Recommendations on the health outcomes of infant formula supplemented with biotics by the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition Special Interest Group on Gut Microbiota and Modifications Trial showing positive outcomes of an infant probiotic and prebiotic intervention in a region with high prevalence of infectious disease: A randomized synbiotic trial to prevent sepsis among infants in rural India About Prof. Yvan Vandenplas MD PhD: Yvan Vandenplas did his medical studies at the ”Vrije Universiteit Brussel” (Free University of Brussels) and trained in pediatrics (1981-1986) at the same University. He became Head of the Unit for Pediatric Gastroenterology and Nutrition in 1987 and created the Pediatric Hospital, the KidZ Health Castle, at the University Hospital Brussels (UZ Brussel) of the same university, where he had the Chair of Pediatrics since 1994 up to 2021. He is now Prof. Emeritus and consultant at the same hospital. He is associate editor of Nutrients.

This episode features Dr. Eirini Dimidi PhD RD from King’s College London (UK), speaking about the recently published British Dietetic Association’s guidelines for dietary management of chronic constipation. Constipation can be a major concern for patients, but evidence around some of the most common dietary recommendations for addressing it has remained unclear. After a thorough review of evidence from randomized, controlled trials, Dr. Dimidi and colleagues found evidence for specific foods / beverages improving certain symptoms of constipation. In addition, some supplements such as psyllium, certain probiotics, and magnesium oxide have evidence for efficacy. A high-fiber diet is a commonly recommended dietary strategy for chronic constipation, but the guideline shows that the evidence to date is insufficient to support this recommendation. (However, a high fiber diet has many other benefits.) Probably the effective foods’ key mechanism of action in relieving symptoms of constipation is the fiber they contain, but future studies need to confirm this. Regarding probiotics, so far the evidence is ambiguous around which strains and which durations of treatment are the most effective so the authors were unable to make a confident conclusion. However, for practical reasons they included the expert opinion that patients should be advised to take a probiotic of their choice for at least 4 weeks in addressing chronic constipation. Episode abbreviations and links: 2025 guidelines: British Dietetic Association Guidelines for the Dietary Management of Chronic Constipation in Adults 2019 review on fermented foods & gastrointestinal outcomes: Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease LinkedIn profile for Dr. Dimidi About Dr. Eirini Dimidi PhD RD: Dr Eirini Dimidi is an Associate Professor in Nutritional Sciences at King’s College London. She is a registered dietitian and nutritionist since 2011, after completing a BSc in Nutrition and Dietetics and a MSc in Clinical and Public Health Nutrition. This was followed by the completion of a PhD from King’s College London where she investigated the effectiveness of probiotics in people with chronic constipation. She is leading research on nutrition-based interventions, including fibre, prebiotics, probiotics, plant foods, and plant-based diets in gut function and dysfunction. She is also investigating the mechanisms through which nutritional interventions may affect immune and mental health via the gut microbiome. Dr Dimidi led the development of the first ever UK national dietary guidelines for the management of chronic constipation, which have been endorsed by the British Dietetic Association. Dr Dimidi was awarded the 2023 Cuthbertson Medal by the Nutrition Society, and the 2022 ISAPP Glenn Gibson Early Career Research Prize for her research on the effect of diet in gut health. She also received the 2021 Rising Star and 2020 Elizabeth Washington awards by the British Dietetic Association.

This episode features Prof. Kevin Foster PhD from University of Oxford (UK), speaking about his lab’s ecological approach to the gut microbiome and efforts to understand and predict dynamics of different species in the microbiome. They also focus on how these ecological dynamics map onto health outcomes, and how they inform interventions. In a 2023 paper, they explored the concept of colonization resistance in the gut, and why certain bacteria or combinations of bacteria are particularly good at preventing pathogens from thriving. Both diversity and composition are important for determining the extent to which a community resists a pathogen. But a microbiome may equally resist a probiotic that’s introduced because the probiotic microorganism doesn’t have access to a unique nutrient. How bacteria interact with each other can help determine resiliency or stability of the microbiome overall. While it’s true that hundreds of species of bacteria exist in the gut, the scale at which the microbes interact locally is much more limited (on the scale of tens of species). Episode abbreviations and links: 2023 paper examining colonization resistance against 2 pathogens: Microbiome diversity protects against pathogens by nutrient blocking.  About Prof. Kevin Foster PhD: Professor Kevin Foster FRS is the Chair of Microbiology at the Dunn School of Pathology, University of Oxford. Prior to this, he was Professor of Evolutionary Biology in the departments of Biology and Biochemistry at Oxford. Before Oxford, he had a lab at Harvard as a Bauer Fellow in the FAS Center for Systems Biology. He did his undergrad at Cambridge in Natural Sciences and his Ph.D. at the University of Sheffield in evolutionary biology. Professor Foster’s research integrates the traditional fields of ecology and evolution with the latest methods in computation, microbiology, molecular genetics, and the study of the mammalian microbiome. The lab focuses on how bacteria compete and succeed in their communities and seeks to use this to manipulate gut communities for better health.

This episode features Dr. Joao Xavier PhD, a systems biologist from Memorial Sloan Kettering Cancer Center, speaking about the application of ecological principles and tools to individuals being treated for cancer. His lab combines multi-omics profiling with ecological models to generate insights on how microbes interact with each other, for application to clinical risk prediction and microbiota-focused interventions. He has studied individuals receiving bone marrow transplantation, who take antibiotics to prepare for treatment; the antibiotics cause significant gut microbiota shifts and the risk of bloodstream infections increases, so his lab is looking at whether the gut microbiota could mitigate this risk. Currently microbiome monitoring is not being used clinically in patients receiving cancer treatments, but a path exists for gaining the evidence needed to make this feasible and useful. Potentially, microbiome monitoring could allow physicians to move from reactive treatment with antibiotics to proactive intervention that prevents serious infections. Or the clinician could simulate potential treatment scenarios and figure out which one is the most beneficial. Probiotics could be administered to shape the microbiome – but rather than adding microorganisms that may simply be missing, these probiotics would be developed by thinking about the microbiome outcome and how to pressure the ecosystem in a certain direction. Episode abbreviations and links: Review in Nature Reviews Clinical Oncology, arguing for the relevance of microbiota management guided by ecological principles in cancer care: making the case for Ecological management of the microbiota in patients with cancer Mouse study investigating what may drive an increase in oral bacteria within the fecal microbiota and how it may link to patient outcomes: Oral bacteria relative abundance in faeces increases due to gut microbiota depletion and is linked with patient outcomes About Dr. Joao Xavier PhD: Joao B. Xavier, PhD, is a faculty member in the Program for Computational and Systems Biology at Memorial Sloan Kettering Cancer Center in New York. His lab combines experiments, computational modeling, and clinical data to study how the human microbiota influences cancer treatment outcomes. Dr. Xavier’s work has uncovered links between gut bacteria, immune recovery, and infection risk in patients undergoing intensive therapies such as allogeneic hematopoietic stem cell transplantation. He recently authored a Nature Reviews Clinical Oncology article (2025) proposing “ecological management” of the microbiota in oncology. This approach applies principles of ecosystem management to preserve beneficial microbes, minimize treatment-related damage, and guide precision interventions. He was awarded the 2026 ASM Microbiome Data Prize by the American Society for Microbiology in recognition of these contributions. His group collaborates broadly across clinical and basic sciences to develop microbiota-informed strategies that could improve responses to chemotherapy, immunotherapy, and infection control.