Microbes and Microbiota: Benefits and Risks

Fourth of Five Reasons to Follow SRA

Join SRA webinars (FREE even to non-members) to connect with others interested in assessing, communicating, or managing risks and benefits.

The 4th of 5 reasons to follow Society for Risk Analysis (SRA) is that by following, members and non-members get notice about upcoming FREE SRA webinars that might align with your passions and interests. SRA has sponsored over 30 webinars to date on diverse and fascinating issues on risks, benefits, and uncertainty (list appended). SRA webinars are FREE and open to the public, with advance registration required. The only limitation for non-members is that access to the recorded podcasts of SRA webinars is a members-only benefit.


SRA’s decision to provide FREE webinars has attracted more than 2,000 people who registered for webinars in the past two years. Many topics of SRA webinars focus on what people fear about exposures of humans and the environment to chemical, physical, and microbial hazards that could cause adverse effects, illness, and death. Two of the top three SRA webinars cover Core Subjects of Risk Analysis: Introduction and Overview: Fundamentals of Risk Analysis by SRA President Terje Aven from University of Stavanger, Norway; and Risk Communication and Risk Perception by John Besley from Michigan State University. Congratulations to Dr. Besely who was recently appointed Area Editor for the SRA journal Risk Analysis in the Risk Communication area, succeeding SRA President-Elect Katherine McComas, his professor during his PhD program at Cornell University.

The SRA webinar that attracted the highest number of registrations was on an interdisciplinary topic of widespread interest that fascinates diverse audiences: the ‘microbiome revolution’ that began with development of methods for detecting microbes without culturing (culture-independent, genetic methods) and then applied those methods in research, including the Human Microbiome Project. The top SRA webinar was entitled Protecting the Human Superorganism, based on a recent book of the same title, with a subtitle How the Microbiome is Revolutionizing the Pursuit of a Healthy Life.


The presenter was author, Rodney Dietert, a professor of immunotoxicology at Cornell University, who was invited to kick off the 2017 SRA webinar series on the microbiome and the microbiota of milks. His research is holistic and ecosystem-oriented, including strategies to reduce acute and chronic diseases by focusing on the microbiome and the immune system. Dr. Dietert recommends managing our microbes as an ecological system before disturbing protective microbes with pharmaceuticals that can exacerbate disease. His pioneering work on the role of the microbiome in human health earned him and 36 other researchers around the world a 2018 ‘Microbiome Hero’ award for educating us to ‘mind our microbes’. The award celebrated the first World Microbiome Day, and awardees were selected by a diverse international committee organized by APC Microbiome Ireland. Dr. Dietert’s recommendations for ‘human superorganisms’ in 2016 and 2017 are even more relevant in 2018. His 2018 paper in the pediatric journal NeoReviews (reference appended) aligns with new collaborative research funded by Science Foundation Ireland. The new Microbe Mom project launched in Ireland seeks to optimise ‘diet and the nature of food and supplements [including probiotics and prebiotics] for pregnant women and babies … crucial to ensuring their health and wellbeing throughout their lives’, a benefit/risk message consistent with Dr. Dietert’s research initiatives on microbes that promote healthy gut and immune systems in neonatology and more generally in public health.


Dr. Dietert included in his 2016 book (and his 2017 webinar and 2018 seminar for Upstate NY SRA) a key slide describing self-completion of the human-microbial superorganism. Self-completion or seeding of beneficial microbes occurs largely through natural childbirth and breastfeeding, as well as via environmental and family sourced microbiota. However, modern patterns of behavior are linked to microbiome depletion, the loss of ‘colonization resistance’ by healthy gut microbiota that normally protect against pathogens (see more below), and the global epidemic of inflammation-driven non-communicable diseases (NCDs; e.g., asthma, inflamatory bowel disease, leaky gut, obesity). Katherine McComas, who served as rapporteur of the 2018 Upstate NY SRA event, commented that microbiome destruction is a fearful message that may prompt emotional responses in many audiences that all is lost!

Not so fast! Dr. McComas was relieved that all is not lost! Dr. Dietert points out that people do have choices about diet, supplements, and therapeutics that could restore their microbiota and their health! Research is beginning to support new options to study and nurture our microbial gatekeepers, our key connections to the external world! SRA risk practitioners will be interested in recent studies from Dr. Dietert and collaborators point that to the need for new environmental health assessment frameworks that include the microbiota so that pharmaceuticals and other potential hazards to microbiome destruction can be properly tested and effectively managed. Testing for mediation of effectiveness of drugs by the microbiome, including the commonly prescribed heart medication digoxin, is especially important, since narrow margins exist between effective, ineffective, and lethal doses for this drug, conditional upon certain microbes.


The 2017 webinar described the importance of colonization resistance as a well-documented ecological concept, particularly well studied in recent years because of the epidemic of hospital-acquired infections such as Clostridium difficile enteritis. Who would have thought before ‘Microbiome Heroes’ like Rodney Dietert fueled the ‘microbiome revolution’ that metabolites of pathogenic microbes could be detected by a dog! For more about the story of Cliff, the ‘C. diff‘ sniffing dog, click here.

Of course, I connected with Dr. Dietert’s emphasis on colonization resistance as part of holistic health since my roots as well as his were immersed in study of the ‘Nurmi concept’ that Salmonella could be excluded from chicks by seeding them with protective bacteria in feces of healthy adults. The slide below illustrates continued use of products that promote health and colonization resistance in poultry.


Although an earlier version of the slide below was included in the 2017 webinar, I included a more current version updated by Dr. Dietert this year. This version of the slide below dramatically illustrates the importance of his findings, as well as the critical roles that the breastmilk microbiota play in development and maturation of healthy gut and immune systems in neonates.

  • Failure to ‘self-complete’ in the newborn may be the single greatest health risk across a life time.

  • Early life is the best time to prevent disease.

  • Management of the “second genome” (i.e., the microbiota; seed, feed, protect) is needed.’

Your questions and comments are welcome. References for key papers by Dr. Dietert follow.


Recent References by Rodney Dietert

1. Dietert RR. 2018. A Focus on Microbiome Completeness and Optimized Colonization Resistance in Neonatology. NeoReviews 19(2):e78-88.

2. Dietert RR. 2017a. Safety and risk assessment for the human superorganism. Human and Ecological Risk Assessment 23(8):1819-1829.

3. Dietert RR. 2017b. The microbiome-immune-host defense barrier complex (microimmunosome) and developmental programming of noncommunicable diseases. Reproductive Toxicology 68:49-58.

4. Dietert RR. 2016. The Human Superorganism: How the Microbiome is Revolutionizing the Pursuit of a Health Life. Dutton, NY, NY. 341 p.

5. Dietert RR, Silbergeld EK. 2015. Biomarkers for the 21st century: Listening to the microbiome. Toxicological Sciences 144(2):208-16.

6. Dietert RR. 2014. The Microbiome in Early Life: Self‐Completion and Microbiota Protection as Health Priorities. Birth Defects Research Part B: Developmental and Reproductive Toxicology 101(4):333-40.

7. Dietert RR. 2013. Natural childbirth and breastfeeding as preventive measures of immune-microbiome dysbiosis and misregulated inflammation. Journal of Ancient Diseases & Preventive Remedies. 1(2):1-8.

List of SRA Webinars

  1. October 24, 2018, The Mechanics of a System of Guidelines for Analysis Supporting Risk Management Decisions. Trying Out a New Perspective: Analysis Quality Challenge Process, by John Lathrop

  2. September 26, 2018, Toward Safer Consumer Products: Exploring the Use of Multi-Criteria (MCDA) and Structured Decision Making (SDM) Approaches for Chemical Alternatives Assessment, by Christian Beaudrie and Charles Corbett

  3. September 5, 2018, Core Subjects of Risk Analysis: Applied Risk Management: A Company Perspective, by Willy Roed.

  4. August 2, 2018, Core Subjects of Risk Analysis: Risk Communication & Risk Perception, by John Besley

  5. June 6, 2018, Counteracting the Politicization of Science, by Toby Bolsen.

  6. May 2, 2018, Core Subjects of Risk Analysis: Risk Management & Policy, by Terje Aven and Frederic Bouder

  7. April 9, 2018, Risk Assessment: From Expert Judgement to Big Data, by Seth Guikema

  8. February 7, 2018, Core Subjects of Risks Analysis - Introduction and Overview: Fundamentals of Risk Analysis, by Terje Aven

  9. November 9, 2017, Webinar on SRA: Who We Are & Opportunities to Engage, by Margaret MacDonell and Terje Aven

  10. October 17, 2017, Webinar on Development and Resilience: Introducing the Fifth SRA World Congress on Risk, Cape Town, South Africa, 6-8 May 2019, by Igor Linkov and Dalila Antunes

  11. September 13, 2017, How do we write and promulgate domain-specific guidelines for analyses supporting risk management? Issues & arguments.

  12. August 29, 2017, Advancing the Science Webinar Series 4th Installment: Preparing to Deliberate Evidence on Benefits and Risks Posed by the Microbiota of Milks, by Peg Coleman and Warner North

  13. July 25, 2017, Elimination of Measles and Rubella: Managing Risks to Prevent Adverse Health Effects and Save Money, by Stephen Cochi, James Goodson, Susan Reef and Kimberly Thompson

  14. June 23, 2017, Risk Frameworks for the Simultaneous Intersection of Infrastructure Interdependencies, Infrastructure Usage, and Extreme Events, by Rae Zimmerman

  15. May 23, 2017, Advancing the Science Webinar Series 3rd Installment: Bovine Milk Microbiota, by Mark McGuire

  16. March 21, 2017, Human Milk: Mother Nature's Prototypical Probiotic Food, by Michelle McGuire

  17. February 28, 2017, Prioritizing and Managing Risks of Health Threats with Decision Analysis, by Gilberto Montibeller

  18. February 14, 2017, Methods for National Security Risk Quantification and Optimal Resource Allocation,by Robert Brigantic

  19. January 24, 2017, Protecting the Human Superorganism, by Rodney Dietert.

  20. January 10, 2017, The Frank R Lautenberg Chemical Safety for the 21st Century Act (LCSA), by Jeff Morris, Karyn Schmidt and Richard Williams.

  21. October 14, 2016, Disaster Resilience of Systems: Quantification and Economic Valuation for Decision and Policy Making, by Bilal Ayyub

  22. September 19, 2016, Multiple Numeric Competencies in Risky Judgments and Choices, by Ellen Peters

  23. August 31, 2016, Webinar on Principles, Guidelines and Core Knowledge for Analytic Support of Risk Management by John Lathrop

  24. July 26, 2016, Welcome and Introduction to the Society for Risk Analysis by James H. Lambert and Margaret M. MacDonell

  25. June 29, 2016, A Causal Analytics Toolkit (CAT) for Assessing Exposure-Response Relations in Epidemiological Data by Tony Cox

  26. February 29, 2016, Predictive Modeling and Risk Analysis by Seth Guikema

  27. January 26, 2016, Adversarial Risk Analysis by David Banks

  28. November 10, 2015, Risk Analysis and Unconventional Gas Drilling by Bernard Goldstein

  29. October 13, 2015, SRA/Nano Safety Cluster (NSC) Round Table by Igor Linkov

  30. September 23, 2015, Introduction to Foundations in Risk Analysis by Terje Aven

  31. August 27, 2015, Simple Displays of Complex Risk Analysis Information by L. Anthony Cox, Jr.

  32. July 27, 2015, What is SRA? by Pamela R.D. Williams and James H. Lambert