Do We Really Need to Boost Our Immunity?

Do We Really Need to Boost Our Immunity? By Emeran Mayer, MD As the COVID-19 pandemic has engulfed the world, there has never been a time in which topics like Gut Health, Immune Support, Gut Cleansing, and Improvement of Gut Health have been more popular. Suddenly experts from the fields of functional and integrative medicine, nutrition and wellness have all jumped on this new trend. Podcast, master classes, social media posts and advertisements, bestselling books have all driven the frenzy around these topics, while scientific evidence from well controlled human studies have lagged behind. As a clinician and scientist who has studied the gut, its endocrine, nervous and immune systems, and the brain for the better part of my career, it is remarkable to follow this explosion of information and interest. In this edition of the Gut Health Insights, I start with one of the main topics of discussion, the Immune System, and will continue in future editions with Gut Cleansing, Leaky Gut, SIBO and Gut Health in general. The great majority of advice that lay audiences get from books and the experts on social media, implies that we need interventions to boost our immune system, implying that there is a blunted, inadequate, or compromised response of the immune system contributing to many of our chronic health problems, ranging from autoimmune diseases and allergies to colon cancer and Parkinson’s disease, and including the COVID-19 epidemic. However, looking at the science, it becomes quickly apparent, that nothing could be more wrong. As I explain in great detail in The Gut Immune Connection, a maladaptive increase in the engagement of the immune system in response to diet-induced changes in the gut microbiome does play a crucial role in most of the disorders making up our chronic non-communicable disease (CNCD) epidemic. The exaggerated, inadequately restrained response of the gut associated immune system is not only responsible for the number of autoimmune disorders (including inflammatory bowel disorders and celiac disease), allergies (asthma, food allergies) but also for the CNCDs, all of which have been increasing during the past 75 years. Even though there are different immune mechanisms underlying these different groups of disorders, they all share one mechanism, which is the compromised ability of the immune system to turn on the breaks once activated. An important factor in these compromised breaking mechanisms is related to an inadequate production of short chain fatty acids by…

Can We Rejuvenate Our Brain Through a Fecal Microbial Transplant From a Young Individual?

Can We Rejuvenate Our Brain Through a Fecal Microbial Transplant From a Young Individual? By Emeran Mayer, MD While the gut microbiota has been implicated as an important regulator of host immunity, brain health and healthy aging, and age-related changes in the gut microbiome have been linked to cognitive decline and frailty in elderly populations (discussed in detail in The Gut Immune Connection), there is limited evidence for a causal role of the gut microbiota in brain health during the aging process, or for an understanding of the molecular mechanisms involved in it. “…transplantation of the fecal microbiome from young animals was successful in altering the microbial community structure of the microbiome from older animals.” In a recent study published in the prestigious journal Nature Aging by lead author Marcus Boehme from the University College Cork, Cork Ireland, the investigators did a comprehensive study in mice to determine if the gut microbiome plays a role in age-related biological, and behavioral changes, and tried to identify the underlying mechanisms. As such experiments are nearly impossible to perform in human subjects, the investigators transplanted fecal microbiota from either young (age 3–4 months) or old (age 19–20 months) donor mice into aged recipient mice (age 19–20 months). While they found clear differences between young and aged mice in the diversity of microbes before the fecal microbial transplant (FMT), they detected no differences between the number of microbial groups gained or lost between the groups following FMT. However, following FMT, the baseline differences in diversity were no longer significant, e.g. old and young gut microbiota looked the same. his “equalization” involved twenty genera which transitioned in the old mouse microbiome towards young mouse abundance following FMT, including the genus Enterococcus. These findings confirmed that the transplantation of the fecal microbiome from young animals was successful in altering the community structure of the microbiome from older animals. “…the successful transplantation of the microbiota from young donors not only changed several gut microbiota, but it reversed aging-associated differences in peripheral and brain immunity…” Remarkably, the successful transplantation of the microbiota from young donors not only changed several gut microbiota, but it reversed aging-associated differences in peripheral and brain immunity, as well as the expression of metabolites and signaling molecules in the hippocampus, a key brain region involved in memory, of aging recipient mice. Structural and functional changes in the hippocampus has previously been identified in human…

The Wellness Primer, Part II

The Wellness Primer, Part II By Emeran Mayer, MD Life is stressful, and for most people chronic stress has become a regular aspect of daily life. Stress has been part of human life for millions of years and there has been enough time in our evolutionary history to perfect our biological stress response systems in a way that has kept our species alive through natural disasters, wars, famines and pandemics. There are two such systems in our body: the older immune stress response system and the brain’s stress response system, and both are often engaged together. Our organism responds to any situation - in the presence or the future - that is perceived as a threat to our integrity and homeostasis by engaging one or both of these stress response systems. While they have evolved and are optimized to respond to infrequent, but life threatening stresses – the poisonous snake, the wild tiger, the severe injury or the infection, for most people in developed countries, these are no longer the kind of stresses we encounter on a regular basis. (Unfortunately, the worry about being shot remains a persistent stress for a significant segment of the population as highlighted by the series of recent high profile police shootings). Rather, today’s stress most often comes in form of chronic stressors associated with modern life: the dietary stress on our metabolism in form of the unhealthy Standard American Diet (SAD), and the chronic psychological stress on our minds generated by the relentless daily bombardment with negative news, worries about the future, increasing competition, and challenges associated with a lower socioeconomic status (in plain language, poverty). Unfortunately, these two type of stressors often occur together, and the relentless challenge of our stress systems comes at an increasing cost to the health of our bodies and minds. Evolution had not foreseen these kind of stresses which we have never experienced as a species. While the stress response systems keep responding in the same way that has been so adaptive for human life, chronic hyperproduction of the stress mediators cortisol and noradrenaline, and chronic systemic engagement of the immune system are responsible for many aspects of our current chronic non-infectious disease epidemic as I have described in detail in The Gut-Immune Connection. Not everybody responds to these challenges in the same way: the responsiveness of our neurological and immunological stress system is programmed during the first…

The Wellness Primer

The Wellness Primer By Emeran Mayer, MD Wellness and the related state of optimal health are lofty goals for millions of Americans. Unfortunately, it is estimated that only about 5% of the US population fall into this category, while about 45% live in a suboptimal health/pre-disease state (without even being aware of it), 50% already live in a chronic disease state, dependent on multiple medications and interventions of our disease care system (an expression that in my opinion best characterizes our modern healthcare system). An overwhelming amount of epidemiological and scientific evidence supports the idea that the transition from optimal health to predisease and ultimately disease is caused in large parts by the increasing stress our brains and bodies are experiencing during a lifetime, often starting in childhood. While acute, transient stress improves our performance by increasing arousal, excitement and focus on a particular challenge, severe chronic stress engages maladaptive responses of the nervous and immune systems which are damaging to our health. With stress, I’m not only referring to the chronic psychological stresses that we are increasingly exposed to in our modern world; the current pandemic is an excellent example of this challenge. But I also include the chronic metabolic stress that millions of Americans are exposed to without knowing it: the stresses on the gut microbial ecosystem and the closely linked gut health caused by the unhealthy Standard American Diet. The combined influence of these growing psychosocial and dietary perturbations of the normal state of health (also referred to as allostatic load) that has become the new normal in the US population is stretching the resilience of our organism to its limits and is making more and more people dependent on the modern disease care system. In this short video clip above, I provide a brief explanation of the relentless transition that has been occurring in the US and increasingly in developing countries from a state of optimal health and the associated subjective feeling of wellness to the current epidemic of chronic non-infectious diseases. I also provide an understanding of how both psychosocial and dietary stresses interact to result in a maladaptive engagement of the immune system ultimately leading to organ dysfunction and disease. I will follow up in two weeks with the second part of this story, focusing on the preventive and therapeutic strategies supported by scientific evidence that are available to counteract this unhealthy development. If…

Understanding and Treating Irritable Bowel Syndrome

Understanding and Treating Irritable Bowel Syndrome By Emeran Mayer, MD We all know that the mind plays a role in disease, but it cannot be studied scientifically.” From the beginning of my medical career, I was interested in understanding how the brain and the mind interact with the body, and how a dysregulation in these interactions can result in a range of medical problems, ranging from heart attacks to unexplained abdominal pain, and from asthma attacks to non-cardiac chest pain. When I tried to find a thesis advisor for my dissertation in medical school in the early 70s, I typically got the answer from the leading professors that “we all know that the mind plays a role in disease, but it cannot be studied scientifically”. Luckily, after 5 failed attempts, I found the right mentor at the Institute of Physiology at the University of Munich, and embarked on a 4-year period of studying the influence of the brain and specifically the sympathetic nervous system on blood flow to the different layers of the heart. Even though I switched my focus from the heart to the gut during my subsequent clinical training in gastroenterology, I never lost my keen interest in studying brain gut interactions. Around 10% of the US population suffer from chronically recurring symptoms of abdominal pain, discomfort and altered bowel habits, which are the hallmark symptoms of IBS. Even though IBS is the quintessential disorder of brain gut interactions, it has only been very recent that experts of the largest professional IBS organization, the ROME Foundation, came to agree on this definition. “IBS is a disorder of neurotic housewives.” What I experienced during these 50 years could fill a whole book with entertaining anecdotes, hard-to-believe statements by leading authorities, and often conflicting dietary and other treatment recommendations. For example, at an international meeting in the 80s, one prominent thought leader referred to IBS as “a disorder of neurotic housewives”, while another stated that it isn’t “a real disorder” in the first place. Then came the long-lasting period of attributing symptoms to disorders of gastrointestinal motility, e.g. altered contractile activity and intestinal transit, followed by a period obsessed with “excessive intestinal gas production”. While the new theories about IBS that appeared every few years captured the imaginations of clinicians and investigators in the field, my early conceptualization of IBS as a brain-gut disorder was rejected by the majority of…