The Microbiome Could Be the Key to Living 10 Years Longer

Brent: Welcome to Death Clock. I'm your host. Today, we speak with Doctor Brett Finlay about the microbiome. Brett is a Canadian microbiologist and a global leader in infectious disease and microbiome research. He's a professor at the University of British Columbia in the Michael Smith Laboratories, with appointments in microbiology and immunology. He's also the author of two bestselling books, Let Them Eat Dirt and The Whole Body Microbiome.

Brent: And he just released his latest book, written with his daughter, called The Microbiome Master Key, which is an update to The Whole Body Microbiome published about six years ago. We talk about the microbiome and how it relates to health and longevity. Your microbiome is the trillions of microbes—fungi and bacteria—that we have on and in us, and they play a huge role in how healthy we are.

Brent: The more diverse our microbiomes are, the healthier we are; the less diverse, the worse they are. They contribute to things like asthma, heart disease, diabetes, and Alzheimer's. They're really important. And the beauty of the microbiome is that it's different than our genetics—you can change your microbiome. Your environment matters, as do sleep, diet, and exercise. Doctor Finlay gives us a deep dive on what the microbiome is and how it impacts our health.

Brent: I hope you enjoy.

Brent: Doctor Brett Finlay, welcome to the show.

Brett: Thanks for having me.

Brent: So the topic today is the microbiome. This is perfect for our conversation because it's a word that I think we all know. If I stopped someone on the street and asked if they've heard of the microbiome, they'd say yes. But if we started probing them on what it was and why it mattered, we'd find a pretty shallow depth of knowledge, and I would put myself in that category.

Brent: So I'm excited to learn all about the microbiome from you. Before we do that, will you give us your background and how you got into this work?

Brett: Well, I've been in microbiology as a researcher all my life. I studied bacterial diseases like Salmonella and pathogenic E. coli—jokingly, diarrhea was our bread and butter. We studied how these bugs made us sick. Then, about 15 years ago, we started to think: we have all these pathogens in the gut, but what about all those other microbes we know are there?

Brett: What do they do? That field became known as the microbiome. For the listeners, the definition of the microbiome is basically all the microbes living in and on our body. We tend to talk mostly about bacteria, but there are also viruses and single-celled eukaryotic organisms.

Brett: So there's this vast collection of microbes living in and on us that collectively is called the microbiome.

Brent: Just to clarify, that refers to the microbes that are on us as well as inside of us. We talk a lot about the gut microbiome, but the term microbiome refers broadly to both.

Brett: Technically, there aren't many microbes living inside your actual tissues. There are viruses inside cells, but most microbes, especially bacteria, live on surfaces. Most people know about the gut microbiome, but the gut is technically outside the body. It's a tube that runs from the mouth to the anus running through us.

Brett: So technically it's still an outer surface. There are microbes in all sorts of places across your body: your armpits, skin, mouth, vagina, lungs, and upper respiratory tract. But by far the most are in the gut. To give you a sense of the numbers, there are at least as many microbes living in and on you as there are human cells, and they encode about 100 times more DNA than Homo sapiens do.

Brett: I jokingly say we're more microbes than people in that sense. The numbers are astounding as you move down the gut. In the lower bowel at the bottom of the gut, there are so many microbes that a single gram of feces—about the size of the tip of your little finger—contains more microbes than there are people on planet Earth.

Brett: There's a lot there. You just can't see them.

Brent: It's interesting to think of the tube from the mouth to the anus as being outside the body because it's not exposed to the internal tissues, but to air at either end as it goes all the way through.

Brent: So technically, you would think of it as a body surface.

Brett: Scientifically, yes. There aren't many microbes floating around your blood, inside cells, or up in your brain. They are technically on all body surfaces, which includes the gut.

Brent: You wrote Let Them Eat Dirt, which touches on letting kids eat dirt and the impact that has on the microbiome. Then you wrote The Whole Body Microbiome with your daughter.

Brent: What was that experience like? What's it like to write a book with your daughter?

Brett: My daughter Jessica is a gerontology professor in geography at CU Boulder, focusing on social and environmental aspects. Because we complement each other, we didn't butt heads too much. I wrote about the microbiome while she covered healthy aging, the built environment, and aging in place.

Brett: Just this month, we launched our newest book, The Microbiome Master Key, which is a complete rewrite of The Whole Body Microbiome. That's the book we wanted to write six years ago, but the science wasn't there yet. Now we have scientific evidence for specific actions you can take with your microbes to improve healthy aging.

Brett: Things we suspected five or six years ago are now backed by research. We're proud of it. It's a really useful guide if you want to enhance healthy aging through your microbes.

Brent: How important is the microbiome? In my understanding of longevity, I feel it's critical—it's not a fringe topic. It seems relatively new to longevity science, as you mentioned regarding the science advancing over the last six years.

Brent: How would you classify its importance?

Brett: I'm biased as a microbiologist, but I would say it's extremely important. Consider the top ten causes of death in North America, like heart attacks and strokes. Nine of those ten are now known to be associated with microbes. Only one—pneumonia—is a direct bacterial or microbial infection.

Brett: Microbes play a major role in cardiovascular disease, Alzheimer's, dementia, and stroke. Over the last 15 years, we've realized these microbes are central to the entire aging process.

Brett: There's a concept called inflammaging: as you get older, excess inflammation causes tissue damage, which leads to almost every aging condition we discuss. Microbes interact heavily with the immune system, which triggers inflammation in the first place.

Brett: This appears to be a major key. As you age, your microbes can shift toward promoting low-grade inflammation, causing tissue damage. In fact, measuring inflammatory cytokines is a better predictor of your biological age and remaining lifespan than your chronological age in years.

Brett: In animal studies, transferring stool from an old mouse to a young mouse causes inflammation and reduces the young mouse's lifespan. Conversely, transferring stool from a young mouse to an older mouse decreases inflammation and increases lifespan.

Brett: That specific experiment hasn't been done in humans, but it shows where the science is heading. In the last chapter of our book, called "The Fountain of Youth," we explore whether microbes could be the key. They are involved in almost every aging process, and unlike your genes, you can change your microbes quickly—dietary changes can alter them in two or three days. Studies suggest aging is only 20 to 25% genetic, while 75 to 80% is environmental.

Brett: I view microbes as part of that environment because everything you touch, eat, or interact with is filtered through a layer of microbes. They are central to aging, and in recent years, we've realized how significant their role really is.

Brett: Now, what do I see as environment? I see that as a microbe, because everything you do is done through a veneer of microbes. Everything you touch, everything you eat, everything you see, there's these films of microbes everywhere, sort of filtering the outside world to us. So they're, they're they're front and center to this whole aging process. And I think that in the last few years, we've really started to sort of ice cream in the forehead moment.

Brett: These bugs are really playing roles in the whole aging process.

Brent: If we zoomed in on any surface—a desk, or the food we eat—we'd find bacteria, fungi, viruses, and archaea. The microbes we expose ourselves to matter for our health. How do we measure this?

Brent: How do you know if someone has a healthy microbiome versus an unhealthy one?

Brett: You can't tell them apart under a standard microscope—they look similar. We evaluate them through genetics. The field exploded after researchers finished sequencing the human genome and turned their focus to sequencing the human microbiome.

Brett: Bacteria share a common gene sequence called the 16S ribosomal RNA sequence, which serves as a genetic handle to target and sequence differences between species.

Brett: With modern sequencing power, you can sequence everything in a sample and filter out the human DNA using metagenomics, allowing you to identify all the microbial genes present.

Brett: Commercial testing companies can analyze a stool sample or swab to tell you which microbes are present. Defining a "healthy" microbiome is complex. We know what a dysbiotic or unhealthy microbiome looks like: it's dominated by inflammatory microbes associated with disease. However, there is no single "ideal" microbe shared by all healthy people.

Brett: That variation comes from functional redundancy: different microbial species can perform the same biological functions. Two healthy individuals can have completely different microbial profiles. Your microbiome composition is generally more similar to the people or pets you live with than to a twin living elsewhere.

Brett: Environment plays a larger role than genetics in shaping your microbiome. In one study of cohabitating couples in the South Pacific, researchers could identify married partners purely by comparing their microbial profiles. Your microbiome serves as a readout of your environment.

Brett: So that tells you the environment plays more important role than the genetics in your microbial composition. And so there's actually a really exciting study. They're looking at marital status in some island in the South Pacific. And they could tell who is married to who just by looking at the microbes in these people. But I didn't ask them, could you tell who had an affair?

Brett: Not, for example, but you can see where this goes. Yeah. So it's basically it's a readout of your environment. And that's what establishes your microbiome.

Brent: We're not yet at a point where a simple test gives us clear clinical answers. For heart health, a blood panel measures cholesterol, triglycerides, and ApoB to assess risk.

Brent: It feels like microbiome testing is still developing in terms of actionable insights.

Brett: Testing provides data, but translating that list of microbes into specific actions is challenging. If a profile shows inflammatory bugs, the general advice is to adopt an anti-inflammatory diet, like the Mediterranean or MIND diet, to shift the ecosystem.

Brett: We are beginning to develop targeted ways to modify the microbiome. Currently, the most effective methods involve lifestyle modifications like diet, exercise, and overall healthy living.

Brett: And so it's interesting if you're a geek and you want to see what all the microbes are in you, but you know descriptively based on that I now have to do this. That's a little harder to do. Okay.

Brent: So we can test which microbes are present, but with billions of organisms, interpreting specific targets remains difficult. What is a fecal transplant? I've heard you and others mention it in animal studies.

Brent: What is a fecal transplant?

Brett: It's also called fecal microbiota transplant (FMT). It involves transferring stool from a healthy donor into a patient. Early research in obesity showed that transferring stool from an obese mouse to a lean mouse caused weight gain, and vice versa.

Brett: FMT gained mainstream medical recognition through treating Clostridioides difficile (C. diff) infections.

Brett: When patients receive broad-spectrum antibiotics, protective gut microbes are wiped out, allowing C. diff to proliferate and cause severe, life-threatening illness.

Brett: By processing donor stool into a slurry and delivering it via enema or tube, researchers achieved roughly a 95% cure rate for recurrent C. diff, compared to about 25% with standard antibiotics.

Brett: FMT is now an approved medical procedure for recurrent C. diff. Modern approaches are shifting toward refined delivery methods, such as oral capsules or defined microbial consortia.

Brett: Researchers are developing Live Biotherapeutic Products (LBPs)—formulated mixtures of 8 to 12 lab-grown microbes—to treat conditions by using microbes as targeted therapeutics.

Brett: But hopefully they will be this is.

Brent: That sounds somewhat like CRISPR, where you edit or alter specific genes in personal DNA. Here, the collective microbial DNA matters, and if an ecosystem is unhealthy, a transplant replaces those microbes and their DNA.

Brent: It feels similar conceptually to switching genes on or off. Is that a reasonable analogy?

Brett: It's a useful visualization, though the microbiome is more complex. Introducing 8 to 12 microbial strains requires establishing a new ecosystem. In active inflammatory conditions like IBD, high inflammation can prevent introduced microbes from colonizing successfully.

Brett: Patients may require pretreatment to reduce inflammation or clear niches so introduced gut microbes can successfully engraft and form a healthy, stable ecosystem.

Brett: And then it does this biochemical process that leads to health, basically.

Brent: Another metric for microbiome health is diversity. An undisturbed rainforest has high biodiversity, making it a resilient ecosystem.

Brent: A lava field has low diversity and limited ecological function. Is the same principle true for our microbiome?

Brett: Yes, ecological principles apply here. Diversity is a standard metric in sequencing reports, and higher microbial diversity generally correlates with better overall health, with a few specific site exceptions like the vaginal microbiome.

Brett: It's healthy anyway. But and most places higher diversity is better.

Brent: Is that because a balanced ecosystem prevents a single pathogenic organism from dominating through competitive interactions?

Brett: Yes, diversity enhances resilience. A broad range of microbial genes improves the ecosystem's capacity to break down toxins or pollutants. A diverse microbiome prevents a single species from dominating.

Brett: For example, Vibrio cholerae infection causes cholera by overgrowing into a monoculture, leading to severe, rapid fluid loss.

Brett: And yeah. So that's obviously very unhealthy. So yeah. You want diversity.

Brent: How do you view over-sanitization? Hand sanitizers became ubiquitous during and after COVID-19, and many people assume sterile environments prevent illness.

Brent: While hygiene is beneficial, does excessive sanitization negatively affect the microbiome? How should we balance handwashing and surface cleaning?

Brett: Historically, after Louis Pasteur and Robert Koch proved microbes cause infectious disease, pasteurization, sterilization, and hygiene practices transformed public health.

Brett: Infectious disease mortality plummeted worldwide due to sanitation, clean water, and antibiotics. Alcohol hand sanitizer, developed in 1966, kills 99.99% of microbes on contact.

Brett: However, as infectious disease rates dropped, non-communicable chronic conditions—such as asthma, IBD, obesity, diabetes, and Alzheimer's—increased sharply. In eliminating pathogens, we also removed commensal microbes that support immune regulation.

Brett: That collateral damage inspired our book and documentary, Let Them Eat Dirt, exploring the consequences of overly sterile environments for child development.

Brett: During the COVID-19 pandemic, public health measures re-emphasized extreme hygiene and isolation, which temporarily reduced environmental microbial exposures.

Brett: Across generations, modern lifestyles are becoming cleaner, and ancestral microbial species are disappearing from urban populations. Microbial diversity is lower in younger generations than in previous ones.

Brett: Researchers are biobanking ancestral microbes from isolated indigenous populations to preserve strains that may be lost in industrialized societies. While targeted hygiene prevents infection, excessive sterility deprives us of microbes necessary for immune training.

Brett: And that's leading to many of our current health problems in our society.

Brent: My wife and I used to wipe down kitchen counters nightly with antibacterial sprays. We've stopped using harsh chemicals and now clean with water or plain soap. Was that the right choice?

Brett: No, no.

Brent: So you would advise against using antibacterial sprays routinely?

Brett: Avoid routine antibacterial products. Overuse selects for resistant bacterial strains on home surfaces.

Brent: So washing counters with standard soap and water is sufficient?

Brett: Use soap, a.

Brent: Standard soap and water.

Brett: Plain soap and water works well. Hyper-hygienic practices, such as sanitizing children's hands repeatedly at playgrounds, are unnecessary in non-clinical settings.

Brett: Young children naturally put objects in their mouths, an evolutionary behavior that exposes their developing immune systems to environmental microbes. Excessive sanitization disrupts this natural exposure.

Brett: Targeted hygiene is still necessary for actual hazards like visible mold or raw food contamination, but routine living environments do not need to be hyper-sanitized.

Brent: So over-sanitizing everyday home surfaces isn't just unnecessary; it can actively compromise normal microbial diversity?

Brett: It is. Yes, very much so.

Brent: What about basic hygiene practices like handwashing after using the restroom?

Brett: Handwashing remains essential, especially when preparing food or after using the restroom.

Brent: You want to if you want to waive the flag of not doing that. Yeah.

Brett: Basic food safety practices are critical. For example, using a basting brush on raw meat and returning it to a shared sauce bottle can transfer harmful bacteria like E. coli or Salmonella.

Brett: Similarly, cutting boards used for raw poultry should be washed thoroughly before preparing raw vegetables to prevent cross-contamination.

Brett: These are sensible hygiene standards. Overusing alcohol hand sanitizers outside clinical settings can strip healthy skin lipids and commensal skin flora, occasionally predisposing skin to irritation or opportunistic pathogens.

Brent: Does this apply to bathing habits? Daily showering with harsh soaps has become modern standard practice, but does it strip protective skin microbes?

Brett: Modern societies generally shower more frequently than in past centuries. While aggressive scrubbing with strong deodorizing soaps can alter skin pH and surface oil balances, definitive data showing adverse clinical outcomes from daily showering is limited.

Brett: I would argue that you can ease off on that a bit. I have not found any good data that, oh, we're sharing too much. Therefore we're, you know, drying out our skin and more bad microbes are coming in and things.

Brent: How important is early-life microbial colonisation? Birth modality varies according to medical necessity, but differences exist between vaginal birth and C-section delivery regarding initial microbial exposure.

Brent: But there's a difference between vaginal birth and C-sections as it relates to the health of the microbiome.

Brett: Microbial interactions begin before birth through the maternal microbiome, which influences fetal development. While the healthy human uterus is largely sterile, birth provides the initial primary microbial inoculation.

Brett: Vaginal delivery exposes the newborn to maternal vaginal and intestinal microbes. These early colonizers help establish gut flora capable of digesting complex oligosaccharides in breast milk.

Brett: Infants born via C-section miss this initial maternal exposure and are colonized predominantly by skin and environmental microbes. Epidemiological studies link C-section delivery with a 25 to 30% higher relative risk for developing pediatric asthma and obesity.

Brett: Research into vaginal seeding techniques after C-section is ongoing to evaluate whether artificial restoration of these microbes lowers disease risk. Our research indicates that gut microbial composition within the first 100 days of life can predict asthma susceptibility.

Brett: Early microbes direct immune system maturation, determining whether immune responses trend toward allergic pathways. Identifying missing pioneer microbes could enable early interventions to prevent pediatric asthma. Early antibiotic exposure also disrupts these foundational developmental pathways.

Brett: Early colonizers support immune, gut, and neural development. Animal models demonstrate that germ-free environments lead to aberrant brain and immune architecture, illustrating the necessity of co-evolved microbes.

Brett: David Vetter, famously known as "the Bubble Boy," lived in a sterile isolator due to severe combined immunodeficiency (SCID), illustrating the extreme challenges of existing without normal microbial interactions.

Brett: I view life as having two critical developmental windows for the microbiome: early infancy during immune establishment, and older age past 65, when microbial composition often destabilizes.

Brett: And then late in life, once you're 65, your microbes fall off a cliff and it's all about aging kind of thing. So that's when they play even bigger roles.

Brent: Is environmental exposure to dirt and microbes more critical during early toddlerhood than in adulthood?

Brett: Yes. Critical developmental windows for asthma immunity occur within the first year, whereas neurodevelopment continues through early childhood. Environmental exposures during toddlerhood actively train physiological systems.

Brett: When infants transition from milk to solid foods, the gut microbiome shifts dramatically toward species that degrade complex plant polymers and dietary fibers.

Brett: By ages two to three, the gut microbiome stabilizes into an adult-like configuration. Minor shifts occur during puberty, but adult microbial profiles remain relatively steady under consistent lifestyle conditions.

Brett: Major structural changes require significant environmental shifts, such as transitioning between omnivorous and vegan diets or relocating between distinct geographical cultures.

Brett: Around age 65, microbial diversity often declines, while pro-inflammatory organisms increase. Modulating the microbiome during older adulthood is key to healthy aging.

Brent: Why does that shift happen around age 65?

Brett: Multiple factors contribute: intestinal epithelial permeability increases with age, allowing microbial products to translocate into circulation. Concurrently, shifts toward inflammatory microbes elevate systemic inflammation.

Brett: Structural gut barrier decline may parallel skin collagen breakdown in aging tissues. Interestingly, studies of supercentenarians (those over 110) reveal highly unique microbial profiles that differ from average elderly populations.

Brent: Crazy good or crazy different.

Brett: In general populations, health status in late adulthood correlates closely with gut microbiome health and low inflammatory markers.

Brett: Five key lifestyle factors substantially support healthy aging and microbial health: diet, exercise, sleep, stress management, and social community. First among these is healthy eating.

Brett: Diets rich in plant diversity—like the Mediterranean or MIND diets—provide complex dietary fibers that feed beneficial microbes. In fermenting these fibers, microbes produce short-chain fatty acids (SCFAs) like butyrate, which nourish colonocytes and suppress systemic inflammation.

Brett: Adherence to the MIND diet—a combination of the Mediterranean and DASH diets—is associated with up to a 53% reduction in Alzheimer's disease risk in high-adherence groups.

Brett: Our research showed that strict MIND diet adherence was associated with delaying Parkinson's disease onset by up to 17 years in women and nearly a decade in men.

Brent: How do you evaluate supplemental dietary fiber?

Brett: Fiber supplements and fermented foods are beneficial additions. Highly processed foods containing refined sugars and simple starches absorb rapidly in the upper small intestine, depriving distal colonic microbes of fermentable substrates.

Brett: Low-fiber diets starve beneficial saccharolytic bacteria, encouraging inflammatory species to proliferate instead. Fiber intake ensures adequate substrate reaches the lower gut.

Brent: Ultra-processed diets effectively leave colonic microbes without nutrients.

Brett: In addition to nutrient depletion, additives in ultra-processed foods can adversely alter microbial composition. Minimizing these foods is key for gut health.

Brent: You ranked diet first among lifestyle factors influencing the microbiome. Where do exercise, sleep, and stress fit in?

Brett: Diet is primary, followed by physical activity. Regular moderate exercise promotes a healthier, more diverse microbial profile. Sleep quality also interacts with microbiome composition.

Brett: Emerging research shows bidirectional signaling between gut microbes and sleep architecture. Fourth is chronic stress management.

Brett: Elevated neuroendocrine stress hormones select for pro-inflammatory microbial profiles and increase gut permeability.

Brett: The fifth factor is social connection and community interaction. Regular contact with family, nature, pets, and diverse environments facilitates beneficial microbial exchange.

Brett: These factors mirror observations in "Blue Zones"—regions like Okinawa (Japan), Sardinia (Italy), Nicoya (Costa Rica), Ikaria (Greece), and Loma Linda (California) where people frequently live past 100.

Brett: Analyzing Blue Zone lifestyles through a microbiological lens reveals consistent patterns: high fiber intake from plant-rich diets in Sardinia, Ikaria, and Okinawa, paired with active daily movement.

Brett: In Loma Linda, vegetarian dietary habits avoid high red meat consumption, which can produce pro-inflammatory microbial metabolites like TMAO.

Brett: Strong intergenerational family structures, low chronic stress, and active social engagement promote diverse, resilient microbial ecosystems.

Brett: Lifestyle practices that promote longevity operate partly by supporting a balanced gut microbiome and curbing chronic inflammation.

Brett: And again, I would argue that most aging processes are going through these microbes. And so you can do something about them.

Brent: Viewing community interaction through a microbial lens is fascinating—beyond emotional support, physical proximity to others promotes microbial exchange and diversity.

Brett: Shared environments directly shape microbial profiles. Studies show that cohabiting individuals share significant bacterial overlap due to close contact and shared living spaces.

Brent: How do medical procedures affect the microbiome? For example, how does colonoscopy bowel preparation impact gut flora?

Brett: Colonoscopy screening is vital for colorectal cancer prevention. I sampled my own microbiome before and after bowel preparation, which temporarily flushes out most luminal microbes.

Brett: The gut ecosystem typically recovers rapidly, returning close to baseline composition. Repeated antibiotic courses cause more persistent alterations.

Brett: Multiple antibiotic courses can permanently alter microbial composition. Following bowel prep, consuming high dietary fiber and fermented foods helps restore normal flora quickly.

Brett: And I swore that can be a microbe. But ironically, it took my gut a while to get back to it. You know, constipated for a while, but I was determined. Eight tons of fiber and I eat every fermented food I can get my hands on it. And it did come back, so they're pretty resilient in that sense. I would say antibiotics is a huge one.

Brett: But do you.

Brent: Do three antibiotic courses cause long-term disruptions within a short timeframe?

Brett: Multiple treatments within a year or two can produce lasting shifts in gut community structure. Broad-spectrum antibiotics affect commensal species alongside target pathogens.

Brett: While targeted antimicrobial tools like CRISPR phages are in development, current options broadly disrupt gut ecology. Antibiotics are life-saving when clinically necessary, but judicious use protects gut flora.

Brett: For self-limiting viral conditions like otitis media or upper respiratory infections, avoiding unnecessary antibiotic use prevents off-target disruption to the microbiome.

Brett: And I think you can actually, you know, help you plan things as you go along a bit better.

Brent: What is your view on commercial probiotics and prebiotics?

Brett: Probiotics are defined as live microorganisms that confer a health benefit when administered in adequate amounts. Specific clinical indications require verified strain-specific evidence rather than generic supplements.

Brett: Selecting a probiotic requires matching specific strains to documented clinical endpoints, similar to choosing specialized footwear for different sports.

Brett: Certain probiotics, such as Saccharomyces boulardii or specific Lactobacillus strains, reduce antibiotic-associated diarrhea or recurrence of C. diff. However, dietary supplements do not require FDA phase III trials proving efficacy before marketing.

Brett: Many over-the-counter probiotics pass through the digestive tract without permanently colonizing. Prebiotics are non-digestible substrates that selectively nourish beneficial host microorganisms.

Brett: Synbiotics combine prebiotics and probiotics to improve strain survival. Standard aerobic strains like generic Lactobacillus may struggle to colonize the anaerobic environment of the lower gut.

Brett: That's what we call a symbiotic. And there's some data to say that actually helps those those things occur. But when you think about probiotics, I mean, many are say for example, lactobacillus, which is found the vagina. The vagina is acidic and there's lots of oxygen in there. You put it, you know, ten, 20 million, billion of these things into the gut.

Brett: The future of therapy lies in defined bacterial consortia—formulated biological drugs containing 10 to 20 native intestinal strains that engraft to perform targeted metabolic functions.

Brett: Next-generation Live Biotherapeutic Products (LBPs) undergo rigorous clinical trials to achieve regulatory approval for specific medical indications, including ulcerative colitis and C. diff.

Brett: Isolating functional microbial metabolites—postbiotics—will also allow therapeutic delivery of pure bioactive molecules without requiring live organisms.

Brett: And so we can go that route too. So that's where the future is. But we're just starting to get there.

Brent: So while dietary supplements vary in quality today, future microbial therapeutics will offer standardized, clinically proven options.

Brett: FDA-approved microbial therapeutics will undergo clinical safety and efficacy testing, expanding options for managing gastrointestinal and inflammatory disorders.

Brett: These regulated live biotherapeutics will provide reliable medical treatments distinct from unvalidated commercial supplements.

Brent: How do popular wellness practices like saunas, fasting, hydration, or cold exposure impact the microbiome?

Brett: Evaluating practices through an evolutionary framework is helpful. Data on cold plunges directly altering microbial composition remains sparse.

Brett: Stress response influences physiological signaling, but direct microbial shifts from extreme thermal exposure require further study.

Brent: I regularly use the sauna for mental health benefits, as cardiovascular data supporting sauna use is relatively strong compared to cold exposure.

Brett: If a wellness practice promotes relaxation and stress reduction without risk, it offers value through systemic physiological benefits.

Brent: What research directions excite you most over the coming decade?

Brett: Developing pediatric microbial interventions to prevent asthma is a major advance. The gut-brain axis is currently one of the most promising frontiers in microbiome research.

Brett: Gut microbes significantly influence neurodevelopment and mood. In rodent models, transferring microbiota from stressed or anxious donors induces corresponding behavioral traits in germ-free recipients.

Brett: Research is advancing from observational studies to mechanistic understanding. Identifying specific pathways enables targeted, evidence-based interventions.

Brett: While we cannot guarantee complete prevention of complex neurodegenerative diseases, dietary interventions like the MIND diet provide meaningful reductions in risk population-wide.

Brent: Regarding the gut-brain axis: the gut contains an extensive enteric nervous system. How does that network connect to the gut microbiome?

Brent: How do you how do you think about that? Or is that all bogus? You know, it's a wives tale.

Brett: Gut microbes produce neurotransmitters and precursors, including serotonin, GABA, and tryptophan metabolites. These compounds act locally on the enteric nervous system and signal directly to the central nervous system.

Brett: Primary communication channels include direct neural signaling via the vagus nerve, circulating microbial metabolites, and immune cytokine pathways.

Brett: Clinical trials investigating targeted microbiota therapies for neurodevelopmental conditions show potential for symptom management.

Brent: Your new book, co-authored with your daughter, is The Microbiome Master Key: Harness Your Microbiome to Unlock Whole-Body Health and Lifelong Longevity. You also wrote Let Them Eat Dirt and The Whole Body Microbiome.

Brent: Where can listeners find more of your work?

Brett: The books are available online and through major booksellers. I encourage listeners to evaluate daily health habits through both human and microbial perspectives.

Brett: Adopting microbiome-supportive habits can add a decade of healthy living. Unlike genetics, your microbiome is adaptable and responds quickly to positive changes.

Brent: Thank you for your valuable work and for sharing your insights with us today.

Brett: Thanks for having me. It's been a pleasure.

Brent: Death Clock is recorded in Boulder, Colorado, and San Francisco, California. Music by Patrick Lee, produced by Patrick Gudino, and hosted by Brent Franson.

Brent: Brent is the founder and CEO.