Ep. 47: “Keys to the Kingdom”: How Microbes Shape Our Healthspan and Longevity — with Dr. Oscar Coetzee, Nutrition & Microbiome Researcher

What if a handful of “keystone” gut microbes quietly set the pace at which your gut, brain, and heart age? In this episode, Dr. Regina Druz sits down with nutrition and microbiome researcher Dr. Oscar Coetzee to explore the strains of gut bacteria that behave less like passengers and more like an organ system of their own. They unpack how modern life — antibiotics, acid blockers, low-fiber diets, alcohol, and glyphosate — strips these keystone microbes away, and what happens when the body loses them. Dr. Coetzee walks through specific strains like Akkermansia muciniphila, Faecalibacterium prausnitzii, and Roseburia that lower inflammation, support metabolic health, and even help the body make its own GLP-1 — plus newer human-donor-derived probiotics designed to engraft in the gut rather than pass through. They close on one of the most striking ideas in the conversation: that biological age and chronological age can be pulled apart, and that gut bacteria may be one of the most direct levers we have for real longevity and healthspan. This conversation is educational only and is not medical advice.

Watch on YouTube: A video version of this episode is available on the Own Your Heart Health YouTube channel. Subscribe to be notified of new episodes.

Episode Chapters

[00:00] The “MMs” of Functional & Integrative Medicine
[02:04] Dr. Oscar Coetzee’s Path Into Microbiome Research
[07:05] How Modern Life Damages the Gut Microbiome
[10:34] Fiber Deficiency & Glyphosate’s Effect on Gut Bacteria
[13:38] What Makes a Bacterium a “Keystone” Strain
[17:30] Akkermansia & Natural GLP-1 Production
[21:41] Roseburia & Its Role in Reducing Inflammation
[26:27] How Keystone Microbes Crowd Out Harmful Bacteria
[28:54] Why Traditional Probiotics Fall Short
[32:27] Stool Testing & the Keystone-Strain Protocol
[44:07] Supercentenarians & the Longevity–Microbiome Connection
[49:09] The Mouse Study That Reversed Biological Aging
[50:09] Microbial Ecosystem Therapeutics Explained
[54:25] Gut Bacteria’s Link to Skin Health & Mood

Transcript

[00:00] The “MMs” of Functional & Integrative Medicine

Dr. Regina Druz (00:02): Welcome to Own Your Heart Health. I’m Dr. Regina Druz, your holistic cardiologist. This week we’ll dive into common heart health concerns, uncovering root causes and unpacking scientific discoveries and controversies. The information provided does not constitute medical advice. Please contact your healthcare practitioner before making any changes that may impact your health.

Dr. Regina Druz (00:40): It’s another Friday fun day, and I’m here with a very special guest — but let me tell you my tiny little joke first. I play this on a lot of my conventional colleagues. When I go to more traditional cardiology conferences, people ask me, “Regina, what is this whole thing — integrative medicine, functional medicine? What exactly are you doing?” And remember, these are cardiologists, fairly hardcore individuals, married to their stents and devices. So what I tell them is that functional and integrative medicine is all about the “MMs.” They get confused and intrigued — “What are the MMs?” And the MMs of functional and integrative medicine are the microbiome and the mitochondria. Today I’m with Dr. Oscar Coetzee, who’s going to take us on a world tour of the microbiome ecosystem. Dr. Coetzee, welcome to the show.

Dr. Oscar Coetzee (01:39): Thanks for having me, Regina — it’s good to be here. That’s a great analogy, by the way, the MMs. I might steal it.

Dr. Regina Druz (01:46): I need to bring candy back next time and hand out M&Ms — “this is what functional and integrative medicine is all about.” But Dr. Oscar, tell us who you are and where you come from. I ask all my guests the same question: how did you grow up to be who you are today?

[02:04] Dr. Oscar Coetzee’s Path Into Microbiome Research

Dr. Oscar Coetzee (02:04): It’s a long story, but I’ll shorten it. I was born and raised in South Africa, where I finished high school, my military service, and my first degree — in psychology. Then I came to the United States, did a master’s in psychology, and ended up at Fair Oaks Hospital in Summit, New Jersey, working as a psychologist in codependency, intervention, and substance-abuse counseling. There was a psychiatrist there, Dr. Mark Gold, and back in the early nineties he was already saying, “You should really investigate the connection between mental health and nutrition — there are nutrients and factors we’re not looking at in the psychotherapy and psychiatric model.” At the time I was set on a PhD in psychology, so I brushed it off. Then my mother got very sick. I flew back to South Africa — she’d appeared healthy, lived a reasonably healthy life, didn’t smoke, didn’t drink excessively, and suddenly she was gravely ill. She passed away, and that changed my world.

Dr. Oscar Coetzee (04:00): When I came back to the US, I decided to combine nutrition with the psychological field, and built a practice around that and the metabolic factors that go with it. I went back to school, finished another master’s in nutrition, then a doctorate in nutrition — which is where I am today. As you know as a functional practitioner, the microbiome is literally the base of health, and that’s been known for many years. I started taking a real deep dive into the nutraceutical space — the different microbes and the “tentacles” they have into our chronic disease. One thing led to another, and I’ve had such good outcomes using specific strains of probiotics. But it’s a lot more than that. The most important thing people need to understand is that, as a population, we’ve let our guts down. We take care of our faces and our outward appearance, but we’ve discarded and really hurt our microbiome — and we need to wake up, because in my opinion it’s the base of anti-aging, of neurocognitive health, and of cardiovascular health, your specialty. And before we go further: when people call someone an “expert” in this area — if you truly understand the complexity of the microbiome and how much we haven’t discovered, I don’t think anyone can claim to be an expert. But I guess I’m about as close as you can get.

Dr. Regina Druz (05:26): As close as you can get. It’s so heartening to see so many people coming into integrative, functional, and longevity medicine — and not just from academic interest, but through personal experience. I share that; my own experience, and my family’s, made me re-evaluate healthspan through a different lens. I love that expression — we’ve “let our guts down.” We’ve let our hearts down too, despite all the progress. And it bothers me on many levels, because we’re seeing things nobody thought we’d see — like colon cancer in younger and younger people, which is even reflected in screening guidelines pushing the colonoscopy age younger. So what’s going on, Dr. Oscar? Where are the gaps? Are we thinking about the microbiome the right way or the wrong way? Take us through it, because you have a very unique perspective.

[07:05] How Modern Life Damages the Gut Microbiome

Dr. Oscar Coetzee (07:05): Let’s start with why I think we’ve hurt — or insulted — our guts. It’s not deliberate; it’s a process of biological and structural change in how we live, plus stress. If I take a step back and ask what people’s guts were like five hundred years ago, we don’t really know the exact composition. But what we do know is that there are very key strains in the human microbiome that need to be identified — the ones we only know of now, with likely more to come. There’s a group we call keystone bacteria. That’s not a textbook definition; it’s more this: if you remove the strain, what’s the downstream effect? If it has many, many effects, it’s clearly a keystone. Think of an arch — the stone at the very top is the keystone. Remove it and the whole arch can collapse. Now, modern lifestyle: long-term antibiotic use is definitely hurting the microbiome — not that there’s no place for antibiotics, I’m just naming what affects it. People using proton pump inhibitors (acid-reducing medication) for much longer than the drug is intended for —

Dr. Regina Druz (08:40): Which are linked to heart attacks, by the way — there’s a very large body of research using standardized medical records.

Dr. Oscar Coetzee (08:47): Yes, and that concerns me — the overuse of proton pump inhibitors is critically involved in microbiome destruction. So there are two medication categories. There are others, but those are the key ones most people are exposed to. Alcohol intake sterilizes the gut — which makes sense, because alcohol was historically used to sterilize wounds. Here’s an interesting one for your listeners: macronutrient-isolated diets — the ketogenic, carnivore, or even FODMAP journeys people take to eliminate bloating and distention.

Dr. Regina Druz (09:35): So rigid dietary patterns that don’t necessarily promote metabolic flexibility.

Dr. Oscar Coetzee (09:42): Correct. There are people who make claims for the carnivore diet and cardiovascular health, or ketogenic diets for other conditions — and you can use them as a medicinal intervention, not a permanent lifestyle. There’s decent research on the ketogenic diet and glioblastoma, for instance. But that doesn’t make the diet good for your microbiome — and here we’re only talking about the microbiome.

Dr. Regina Druz (10:12): And for heart failure too. I always tell patients these diets are in the interventional domain. The microbiome needs a foundation. If there’s no foundational diet appropriate for the microbiome, interventional diets take you even further down that road.

[10:34] Fiber Deficiency & Glyphosate’s Effect on Gut Bacteria

Dr. Oscar Coetzee (10:34): Correct. So what do we have so far? Some medications, alcohol, and a non-diverse diet — meaning you’re not eating all the colors and the fiber. Let’s talk about fiber. The average American takes in about 16 grams of fiber a day. Ancestrally, it’s postulated that people ate between 50 and 120 grams. That’s a major issue, because fiber feeds the keystone microbes that keep roughly 85% of our metabolic and immunological health in a good place. Chemotherapy clearly affects it too. And one of the most insidious factors is glyphosate — the herbicides and pesticides sprayed on our foods. These work like antibiotics; they’re chelators, which means they pull minerals out of things. Picture the bacteria in your gut as flora — flowers. If you take away the minerals that feed the flower, it wilts and dies. That’s what glyphosate does. And now we spray it on everything to harvest earlier and industrialize our food. Add stress, being on our phones twenty-four-seven, all the radiation — it’s all affecting the gut. There’s nobody listening in their car or at home who isn’t exposed to this.

Dr. Oscar Coetzee (12:20): So here’s what we did. We teamed up with a functional laboratory — Diagnostic Solutions Laboratory — and asked them to run the data on roughly the last 17,000 stool tests they’d done. For your listeners, this isn’t a disease test; it’s more a measure of how healthy your gut is. And about 65% of the population was low in these keystone strains.

[13:38] What Makes a Bacterium a “Keystone” Strain

Dr. Regina Druz (13:02): Let me ask you here, because this is all coming very fast into my brain. These keystone strains — is it “set in stone,” where we know exactly which strains they are? Or might we discover or define a new keystone strain every few years? How is that determination made? Because depending on how it’s made, some people may or may not be regarded as deficient.

Dr. Oscar Coetzee (13:38): Really good question — I’ve had several discussions with microbiologists about it. There’s no textbook stating “atherosclerosis is associated with X strain.” Keystone is a moving goalpost, because we keep discovering new microbes that fall into the category. However, there are about five or six particular keystones, and we’ll probably talk about three or four today, that have been shown to be a requirement for optimal health. You mentioned colorectal cancer earlier — it’s well documented that people with low Faecalibacterium prausnitzii (I know it’s a mouthful, so we’ll call it “F. prau”) are at higher risk. In geriatric populations, and in neurocognitive decline, F. prau is low. In colorectal cancer there’s a very strong correlation with low F. prau. I’m not saying low F. prau causes colorectal cancer, but its presence clearly helps mitigate the manifestation of it. And F. prau produces a unique byproduct that feeds the microbiome and makes those “flowers” in your gut grow again — that’s why it’s a keystone. It’s not like a probiotic you take that’s just in your body doing a little benefit but not living there; a keystone can go into your gut and, in the right environment and combination, actually engraft, grow, and communicate with the other strains.

Dr. Oscar Coetzee (15:35): The bigger point I want to make: I don’t want people to think of keystone bacteria as just a bunch of bugs hanging out, helping a little with digestion. In my opinion — and it’s just my opinion — they function like an accessory organ system, more like a kidney or a lung. They stimulate byproducts that help you make new cells; they communicate with the cells of your gut lining to express immune and metabolic function. They help you rejuvenate and regenerate.

Dr. Regina Druz (17:03): Regenerative — so they lay the definitive structure of our microbiome, but they also put us on a path of regeneration, which is so important as we get older. Absolutely fascinating. So tell us about the other keystone strains and how we find them.

[17:30] Akkermansia & Natural GLP-1 Production

Dr. Oscar Coetzee (17:30): The other key one everybody’s heard about is Akkermansia muciniphila — or just Akkermansia. That strain is incredible; we could do a whole podcast on it. For the layperson, it helps with insulin sensitivity, fatty-acid breakdown, mitochondrial health (your “MM” theory), and progenitor-cell rejuvenation. But the key thing to remember is that it literally helps you produce endogenous GLP-1. Everybody’s talking about GLP-1 medications — well, you have areas in your gut that make it for you. If you look at lean, healthy people, they’re not low in Akkermansia; weight-loss-resistant people are often detectably low. It’s an association and a pattern, but it’s a striking one. And if Akkermansia is present — and it needs to be, because it’s like an organ — and you eat enough fiber (which most of us don’t), it produces short-chain fatty acids. Akkermansia produces two: acetate and propionate. These go to the cells of your gut lining and “knock on the door” of the receptors and say, “Hey, I’m acetate — I can help you make GLP-1, want to work together?” And the body says, “Yeah — where have you been? I haven’t seen you in months.”

Dr. Regina Druz (19:52): Exactly — in years, sometimes.

Dr. Oscar Coetzee (19:57): So now you start producing natural GLP-1, and suddenly you don’t crave as much garbage, you start losing weight again when you exercise, and you don’t have to count calories to the nth degree. Your body starts modulating and rejuvenating itself. I tell people to think of the microbiome as a youthful playground. Those microbes wake up every morning and ask, “What can I do to help Regina today?” They’re not saying, “I don’t want to go to work.” They say, “I’m going to help you — give me a little fiber, a few colors, reds, greens, yellows, and here’s what I’ll do: I’ll give you GLP-1, I’ll make your mitochondria work better, I’ll help every aspect of how you make energy.” But if they’re low and you’re not eating enough fiber, you can’t expect them to do their job. So — we’ve covered Akkermansia and Faecalibacterium prausnitzii; now let’s talk about Roseburia.

[21:41] Roseburia & Its Role in Reducing Inflammation

Dr. Regina Druz (21:41): I love that name — Roseburia. It sounds like a perfume.

Dr. Oscar Coetzee (21:46): It does. That strain is very unique. And by the way, Regina — for your information as a cardiovascular specialist — all of these strains lower LPS (lipopolysaccharide), which is a driver of inflammation in the gut microbiome. They lower interleukin-6, tumor necrosis factor-alpha, and interleukin-1 beta — the inflammatory agents that drive a lot of cardiovascular and neurocognitive disease.

Dr. Regina Druz (22:20): Let’s stop and make sure everyone’s on the same page, because this is critically important. Time and again we now know the seat of chronic disease is inflammatory in origin. There are multiple root causes, but what executes on those root causes to give a person cardiovascular disease, neurodegenerative disease, or cancer predisposition is an inflammatory process. There’s even a term — one of the hallmarks of aging — “inflammaging,” inflammation plus aging. And the origin of why those inflammatory factors sometimes rise and affect our other organs is often gut-based, because the gut houses most of our immune cells, produces hormones, produces neurotransmitters, and is our first interface with the outside world. There’s an old saying: the path to the heart leads through the gut.

Dr. Oscar Coetzee (23:40): Or the other statement — I think it was Hippocrates — that all disease begins in the gut.

Dr. Regina Druz (23:46): Exactly — still true hundreds of years later. Okay, so — Roseburia.

Dr. Oscar Coetzee (23:56): Remember the rose, the perfume. First, let me say that all the bacteria I’ve mentioned are anaerobic — they don’t like oxygen. That sounds simple, but it’s been very hard to encapsulate them in a supplement, because any time you expose an anaerobe to oxygen, it dies. That’s been the drawback for years — until very recently we couldn’t deliver Akkermansia or Roseburia back to you, because we couldn’t make a product that protected them. Roseburia itself is fascinating. Picture it with a little tail at the back, wagging like a dog’s tail. At some point that tail touches your gut lining — the cells between your gut and your bloodstream — and starts to gently scrape them. The cells say, “Where have you been? Good to see you,” and that “scratch” stimulates something called hypoxia-inducible factor. The cells then express lower oxygen levels — and because Roseburia drives that low-oxygen state, it makes the whole environment more hospitable for all the other anaerobes.

Dr. Regina Druz (25:56): It facilitates its own growth.

[26:27] How Keystone Microbes Crowd Out Harmful Bacteria

Dr. Oscar Coetzee (26:27): Correct — its main job is all these anti-inflammatory effects, but also to make the environment co-hospitable for the other strains that want to be anaerobes. And here’s the caveat: most of the opportunistic “bad guys” don’t like an anaerobic environment; they love oxygen. That’s a lot of your pathogens and opportunists. So imagine you have a group of good guys working as part of your body, like an organ system. As they create this low-oxygen environment, the bad dudes start saying, “You’re smothering me” — and that’s the point: we want to crowd them out. This is what we’ve seen in clinical trials, which is so interesting. Initially all we wanted to know was whether giving people this strain of probiotic could raise Akkermansia, Roseburia, and Faecalibacterium prausnitzii — because those strains are cardiovascular-, metabolic-, neurocognitive-, and regeneration-related. And when we stimulated them with fiber and polyphenols, we saw we started to eradicate opportunistic and some pathogenic bacteria without antimicrobial drugs. That wasn’t even the objective of the trial. The objective was: pre-test low Akkermansia, post-test elevated Akkermansia — and we saw that. But the rest of the test also showed lower opportunistic overgrowth, better zonulin (meaning tighter gut junctions), and increases in other good bacteria we didn’t even provide — Bifidobacterium and Lactobacillus numbers went up.

Dr. Regina Druz (28:28): Those are key — and so hard to manipulate with conventional probiotics. I’m almost giving up on conventional probiotics at this point.

[28:54] Why Traditional Probiotics Fall Short

Dr. Oscar Coetzee (28:54): That’s a good point to discuss. There’s a lot of data supporting traditional probiotics in certain clinical situations — some strains help with diarrhea, some with IBS. But they’re transient: they don’t stay, they don’t engraft, they don’t grow. You have to keep taking them to get the same effect, and honestly they have a bit of a “pixie-dust” effect. Let me explain it. Remember the old bottles of ink in school? Imagine you take one small bottle of ink and dip it into the biggest pond in your area — why isn’t the lake turning blue? Because it’s just a drop in the lake.

Dr. Oscar Coetzee (30:09): But with these anaerobic strains, we give you a small amount, and when they get down there and the cells recognize “Roseburia is back, Akkermansia is back,” they start working together and repopulate the gut. That’s the key. You insert a small amount, and with the right “fertilizer” — fiber — it starts to engraft. Studies show engraftment without any support can last up to six months; obviously we’d rather give the support to help it along. And when you have these keystone strains in abundance, they help keep the others around longer, because they want to work together.

Dr. Regina Druz (31:06): So there’s synergy — an opportunity for synergy. This is fascinating, and I’m 100% going to run out and test myself to see whether I have any Roseburia; my test is long overdue. From a practical standpoint — you’ve alluded to a protocol — how should our listeners approach this? Is there testing involved? What do you advise? Certainly fiber; I support that 100%, and fiber is easy and inexpensive — you can go to Whole Foods, get organic psyllium husk in a bag, and increase your fiber. So what are the practical steps for someone to find out whether they have these keystone strains, and what to do if they’re low or imbalanced?

[32:27] Stool Testing & the Keystone-Strain Protocol

Dr. Oscar Coetzee (32:27): Great question. Remember what causes us to be low in them — so there’s a good chance you’ll have one, two, or all three low. In my opinion, every functional doctor should run one stool test on every patient once a year — the same way you do a CBC or a metabolic panel. They’re not expensive; you can do them for around $289 — that’s about six lattes at Starbucks — and it’s your health. The test is done at home, non-invasive: a kit comes to your house, you do the analysis, and you get the result. You’ll see those strains clearly indicated in the “keystone/commensal” category. When you’re low, you take the probiotic strain. And here’s what we found clinically: if Akkermansia is low but Roseburia and F. prau are normal, taking Akkermansia alone doesn’t move it. If you take three or four of them together, it moves. We also saw that when a strain is high, the body is often compensating — it makes one high because the others are low, trying to bring them back. When we put those people on the combined strains, the high ones normalized rather than going higher. So there’s a natural equilibration.

Dr. Oscar Coetzee (34:51): So once you’ve done the stool test — whether strains are high or low, if any are out of range you start the strain. You take it for about twelve weeks: one small capsule a day. Think of the probiotic as a seed — you put the seed in the gut, and it knows exactly where to go and what to do. It’ll activate on its own, but it’s much more effective if you eat more fiber, more colors, more Mediterranean, more diverse — not a macronutrient-isolated diet.

Dr. Regina Druz (35:24): A phytonutrient-rich diet — sometimes called whole-food, plant-based — but regardless of the name, the idea is the same.

Dr. Oscar Coetzee (35:32): Correct. And unlike other probiotics that are taken without food, I strongly recommend taking these with fiber, because it’s like saying “thank you, team player — let’s make this work.” We’re going to publish this research shortly.

Dr. Regina Druz (35:58): And you’ll send us the article so we can share it with our listeners. I have to hear more about that Roseburia situation.

Dr. Oscar Coetzee (36:02): I’ll come back. After the twelve-week period, how often you take it intermittently depends on the individual. If someone is now eating a Mediterranean diet — colors, seasonal foods, lots of fiber — then with all the outside influences we’re still exposed to, I’d say take it at least once a quarter, and keep testing to see where you’re at. For people living a very compromised lifestyle — they won’t get off keto or carnivore, they drink alcohol — they need to take it more consistently. So it’s really simple: take the probiotic strain, change your diet toward more fiber, and retest to see your status. You don’t have to change every single thing in your world — but if you eat less fiber, you’ll need the probiotic more consistently.

Dr. Regina Druz (37:17): It’s interesting, because a lot of this maps onto a fundamental functional-medicine protocol for the gut — the 5R. The first R is Remove, and it’s so hard for patients to remove those environmental influences — alcohol, sleep disruption, chronic stress, other toxins. The second R is Replace — because fiber can be difficult for some to digest, so from the stool test we might see a need to replace digestive enzymes, or butyrate if they’re low. Then Repair — specific supplementation and nutrition to repair the tight junctions and restore cellular integrity of the gut. Then Reinoculate — where the probiotics come in. And then Rebalance — we go back and ask how well you did with each step. What you’re describing is that if someone is less successful at Remove and Replace, reinoculation plays a more prominent role; if they’re more successful, they may not need to reinoculate as frequently. It’s a dynamic equilibrium — the kind we see in patients who excel at longevity, and it’s been described in the literature as a dynamic longevity equilibrium that starts in the gut. So — what is that probiotic you’re mentioning?

Dr. Oscar Coetzee (39:32): The name is simple: it’s called Complete Commensal. There are two Bifidobacterium strains in there in a supporting role, to ferment starches and feed the main players. And I want to mention one more strain, separate from Complete Commensal, called Anaerostipes caccae — another complicated name.

Dr. Regina Druz (40:15): Honestly, after everything we’ve discussed, you should’ve called Complete Commensal “command and control.”

Dr. Oscar Coetzee (40:26): Ha — maybe. So Anaerostipes caccae is also an anaerobe with a very unique purpose. You mentioned butyrate earlier — butyrate is an extremely important short-chain fatty acid that bacteria produce to heal the gut lining. It also has energy functions; it actively enters the Krebs cycle to help the mitochondria make energy. But its key role is healing the gut lining. Anaerostipes caccae is the highest butyrate-producing anaerobic strain known to our scientific knowledge, so it produces the most benefit, and it also loves lactate — meaning if you’re eating yogurts and lactate-producing strains, you can enforce its feeding. Here’s an interesting study: Anaerostipes caccae was discovered by comparing babies with cow’s-milk allergy to babies without. The one substantial difference in the microbiome was this strain — it was lacking in the kids with the allergy. They isolated it and, in mouse and rat models, even improved anaphylaxis — a remarkable finding, though we don’t promote that for humans. What we have seen in humans is that people with dairy or gluten sensitivity and food intolerances who take Anaerostipes caccae — a major butyrate producer that fixes the gut lining — can start eating the foods they reacted to without the bloating and side effects.

Dr. Oscar Coetzee (43:14): So in our clinical trials we combined Anaerostipes caccae with Complete Commensal in one arm, Complete Commensal alone in another, and Anaerostipes caccae alone in a third. Both combinations showed tremendous promise, and where Anaerostipes caccae stands out is for food intolerances and sensitivities — not allergies, which you and I know is a different mechanism. If you combine the two, it’s ideal for that typical IBS person with bloating and distention who can’t eat certain foods, is low in these anaerobes, has low energy, and has metabolic-syndrome-related issues. And one final point: we looked at the data on anaerobic strains in centenarians. They found eleven unique bacteria at high levels in centenarians — and all four strains we discussed were present. So there’s clearly something there from a longevity standpoint.

[44:07] Supercentenarians & the Longevity–Microbiome Connection

Dr. Regina Druz (44:07): A hundred percent. It’s fascinating because I’m in the final stages of revisions for my first-ever book — it’s called Longevity Switches — and in it I put forward the idea of a “health operating system,” of which the microbiome is a component. That led me to look at supercentenarians — people who’ve lived beyond 112, often over a hundred and ten. One recently passed away — her name was Maria, from a tiny Spanish village; in the research papers she was known as “M116” because she died at 116 years and 47 days. She allowed investigators to take multiple samples over years, studied by a university department in Spain, and they found she had a remarkable microbiome composition. She lived a Mediterranean lifestyle with high dairy consumption, didn’t drink or smoke, and her life was very regimented. Some findings were counterintuitive — her telomeres were very short, which we usually associate with lower longevity, but in her case may have been cancer-protective. Probably the primary reason for her extraordinary setup, though, was that microbiome — it led to low inflammation, good mitochondrial function, and not much frailty. This is fascinating, because we no longer need to think that chronological aging and organ aging march in sync. We can dissociate chronological aging from biological aging, if we do it right — and the microbiome is the “universe,” the organ, that we can manipulate to do so. It’s not that difficult: get a stool test, understand the 5R program, get the probiotic in addition to everything else. It’s not rocket science. It’s about taking ownership of that part of your house and being willing to make the changes.

Dr. Oscar Coetzee (47:12): You have so many good points. The one I’d expand on: as a world, we go about longevity — or anti-aging — completely incorrectly. If we could go back and see that 116-year-old at ninety, I can assure you she didn’t look like a model; she probably had wrinkles and gray hair.

Dr. Regina Druz (47:41): She looked her age.

Dr. Oscar Coetzee (47:42): Right. The point is, we keep working on anti-aging from the outside, trying to manipulate how many wrinkles we have. But the only way to truly promote anti-aging is from the inside out — you have to give the body the things that make it feel young again. That’s the opportunity.

[49:09] The Mouse Study That Reversed Biological Aging

Dr. Oscar Coetzee (48:00): Here’s another study — animal-model, and we’ll learn more as we go, with probably more anaerobes coming in the next five to seven years. They took an old mouse and a young mouse, and transplanted the microbiome from the young mouse into the old one. Within two to three weeks they saw better mitochondrial function, better energy, better recovery from exercise — this gray, old mouse was running around like a crazy young mouse. They also took the old mouse’s microbiome and put it into the young mouse — and, interestingly, the young mouse did not appear to age in response.

Dr. Regina Druz (49:02): So it aged? No —

Dr. Oscar Coetzee (49:09): It didn’t, which is the interesting thing. On a very anecdotal level, that suggests the body recognizes a young microbial environment — some phenotype association worth researching. (This was an animal study, so it does not prove the same would happen in humans.) And that’s why this particular probiotic is unique: it comes from a young human-donor pool that’s been screened and researched for optimal composition.

[50:09] Microbial Ecosystem Therapeutics Explained

Dr. Oscar Coetzee (50:09): Now people will ask, “Wait — are you giving me a fecal transplant?” No, absolutely not. This is something called microbial ecosystem therapeutics. In layman’s terms: we know fecal-matter transplants help people with C. diff and have shown good clinical effect, but the side effect is danger for immunocompromised people — in 2019 the FDA restricted fecal transplant in immunosuppressed patients because it can be dangerous. So imagine you take a healthy individual with no disease state and extract just the microbes — without the “yuckiness,” none of the nastiness — and encapsulate that community and put it in your body. Then you have that young-mouse/old-mouse scenario. So it’s a probiotic with live, active, cultured bacteria. And here’s the difference: all other probiotics come from dairy or fermentation sources. This is why I think we see this level of engraftment — the body recognizes it: “This is a bacteria I know; it’s a human donation, I can work with this.” You can’t take the kidney of a dog and put it into a human — you take a human kidney and put it into a human.

Dr. Regina Druz (51:33): This is fascinating — it almost makes me think of how people bank umbilical-cord blood for stem cells. When babies come into the world, they rapidly become colonized, but they have healthier guts because they’re supported by mother’s milk and haven’t yet experienced all the bad influences. I almost feel this technology should eventually let us have material for our own microbiome therapeutic down the line — a bit “out there,” but maybe science gets us there.

Dr. Oscar Coetzee (52:26): They’re already going there, Regina. At some point — probably in the next hundred years — you’ll be able to say, “Take the extraction from this person in our family line that we know genetically.”

Dr. Regina Druz (52:46): Exactly — like my grandfather, who lived to ninety-six, or my husband’s grandmother, ninety-nine, who had very difficult lives. You’d want some of that “secret sauce” they possessed.

Dr. Oscar Coetzee (53:05): If you look at that 116-year-old centenarian, her microbiome was probably a young microbiome in an older body. So I don’t want to tell people chronological age is the only measure of a young microbiome. A young microbiome is about how revitalized it is, how quickly it rejuvenates, how well you feed it. These microbes don’t live sixty years — they have a short shelf life, but they keep renewing.

Dr. Regina Druz (53:34): They renew themselves. And that’s why I don’t like to call this “anti-aging” — it’s more longevity medicine, because we finally have this dissociation where chronological and biological age can be uncoupled depending on what you do. They can be super-coupled — aging biologically faster than the chronology — or uncoupled, so biological age is actually younger. That’s the brilliant opportunity: to manipulate what we’ve carried in us for millennia, those keystone bacteria.

[54:25] Gut Bacteria’s Link to Skin Health & Mood

Dr. Oscar Coetzee (54:25): One more: Faecalibacterium prausnitzii is known to produce salicylic acid, which is really involved with skin health. In my research I spoke with an integrative dermatologist — rare, because not many practice functional dermatology — who told me about 85–87% of her patients were low in F. prau. When she started giving them F. prau, especially with the introduction of this, she was able to clear things like eczema and cystic acne as F. prau increased. These strains have so many “tentacles.” F. prau is also highly associated with major depressive disorder, because gut bacteria produce hormones and amino acids like tryptophan that make serotonin — put those back and you have it. And where this is going: there will definitely be ethnic investigation into the microbial-donor question — an Asian donor versus a sub-Saharan African donor, for instance. And who knows — maybe they’ll extract from top-level athletes. Which I always guard against, because some of the worst guts I’ve ever seen are in top-level athletes.

Dr. Regina Druz (56:25): Of course — they overtrain and there’s a lot of stress. This is where, with contemporary science and AI — which I use every single day, and I’m sure you do too — I honestly think we’ll reach the point, quicker than people realize, where “digital twins” become replicas of us, so we can apply various permutations to project the future. We’re already doing this at Holistic Heart Centers, taking information from patients who responded positively to lifestyle change and supplementation — measuring, for example, regression of plaque in the carotid arteries, and given enough time even the coronary arteries. So we can go beyond biomarkers and see direct tissue impact — and figure out, before you invest time and money into a path, the likely outcome and how to position yourself. That’s going to be — I won’t call it Medicine 3.0 — maybe Medicine 4.0, or “medicine.ai.” Dr. Oscar, this has been one of my favorite episodes. Tons of great information. We’ll drop all the links, and I promise, to the best of our ability, we’ll spell out these names correctly — you’ll help us. We’ll provide links to these probiotics; I’m going to call them “command and control,” but they’re actually called Complete Commensal. And if you’re interested in working with us in this type of medicine, it’s easy to start — just send us a text or give us a call. Thank you so much for being a guest today.

Dr. Oscar Coetzee (58:53): It was really fun. I hope to come back when we have some of the research.

Dr. Regina Druz (58:57): A hundred percent — I’d love that. And when you come back, I’ll tell you about my own composition of Faecalibacterium prausnitzii, Akkermansia, and Roseburia, because now I’m motivated to get my results. So, listeners — you’ll hear my results on air. Get ready. Thank you for tuning in to Own Your Heart Health with Dr. Regina Druz. This podcast is powered by Holistic Heart Centers. If you enjoyed the show, please rate and review us on your favorite podcast platform. To learn more about our services, visit holisticheartcenters.com and subscribe to our YouTube channel — the link is in the show notes. See you next week.

Frequently Asked Questions

What are “keystone” gut bacteria, and why do they matter?

Dr. Coetzee describes keystone bacteria with the image of an arch: the keystone is the stone at the top, and if you remove it the whole arch can collapse. In the gut, a keystone strain is one whose absence produces many downstream effects — and whose presence supports metabolic, immune, and anti-inflammatory function across the body. Unlike ordinary probiotics that simply pass through, keystone strains can (in the right environment) engraft, grow, and communicate with the gut lining and other microbes. This is a general explanation of an active area of research, not a diagnosis or treatment recommendation.

Which keystone strains did Dr. Coetzee highlight?

Four came up: Akkermansia muciniphila (linked to insulin sensitivity, mitochondrial health, and the body’s own GLP-1 production); Faecalibacterium prausnitzii (“F. prau,” associated with lower colorectal-cancer risk, skin health, and mood via serotonin precursors); Roseburia (which helps create the low-oxygen environment other beneficial anaerobes need, while lowering inflammation); and Anaerostipes caccae (the highest butyrate producer he cites, relevant to gut-lining repair and food sensitivities). All are anaerobes, which historically made them hard to deliver in a supplement. These strain-specific claims are as discussed on the episode and warrant independent verification.

How can gut bacteria help the body make its own GLP-1?

Per Dr. Coetzee, when Akkermansia is present and you eat enough fiber, it produces short-chain fatty acids — acetate and propionate — that signal cells in the gut lining to help produce endogenous (your body’s own) GLP-1, the same hormone targeted by popular GLP-1 medications. He frames adequate fiber as essential “fuel” for this process. This is an explanation of a proposed mechanism, not a claim that supplements replace medication; talk with your own clinician about GLP-1 therapies.

Why do traditional probiotics often fall short?

He uses the image of a drop of ink in a lake: most conventional probiotics are transient — they don’t stay, engraft, or grow, so you have to keep taking them for the same effect. By contrast, the keystone anaerobic strains he discusses are designed to engraft with the right “fertilizer” (fiber) and then repopulate the gut and work synergistically. He still notes traditional probiotics have solid evidence for specific uses (e.g., certain strains for diarrhea or IBS). This reflects his clinical view and is shared for education, not as product guidance.

How would someone test and support their keystone strains?

Dr. Coetzee suggests an annual at-home stool test (he cites roughly $289) that reports your keystone/commensal strains, much like an annual blood panel. If strains are out of range, the protocol he describes is one small capsule of the combined keystone probiotic daily for about twelve weeks, taken with fiber, alongside a diverse, phytonutrient-rich (Mediterranean-style) diet — then retest. Dr. Druz maps this onto functional medicine’s 5R protocol (Remove, Replace, Repair, Reinoculate, Rebalance). These are general wellness ideas, not personalized medical advice — work with your own clinician before starting any testing or supplement program.

Can the gut microbiome really affect biological aging?

Both physicians make the case that chronological age and biological age can be “uncoupled.” They point to a supercentenarian case (a woman known as “M116” who lived to 116) whose remarkable microbiome tracked with low inflammation and good mitochondrial function, and to an animal study in which transplanting a young mouse’s microbiome into an old mouse improved energy and mitochondrial function within weeks. Dr. Coetzee is explicit that the mouse work is an animal study and does not prove the same occurs in humans. These are emerging, hypothesis-generating findings shared for general interest, not proof or medical advice.

Show Notes & Resources

Guest: Dr. Oscar Coetzee, Nutrition & Microbiome Researcher

Dr. Oscar Coetzee is a nutrition and microbiome researcher whose path into the field began far from nutrition — born and raised in South Africa, he trained first in psychology and worked in substance-abuse and intervention counseling before a mentor and a personal loss redirected him toward the connection between nutrition and health. He went on to earn a master’s and a doctorate in nutrition, and today focuses on the gut microbiome and the “keystone” bacterial strains, working in the nutraceutical space and in clinical trials on human-donor-derived, engrafting probiotics (including the Complete Commensal formulation discussed on the episode). He describes keystone microbes as functioning almost like an accessory organ system — supporting metabolic, immune, cardiovascular, and neurocognitive health. (The views shared are his own, offered for educational purposes; some referenced research was described as not yet published.)

Topics & References Mentioned in This Episode

Stool / microbiome testing — Dr. Coetzee references Diagnostic Solutions Laboratory and an analysis of ~17,000 stool tests finding ~65% of the population low in keystone strains (as stated on the episode; verify before citing)
The keystone strains — Akkermansia muciniphila, Faecalibacterium prausnitzii, Roseburia, and Anaerostipes caccae
Complete Commensal — the human-donor-derived, engrafting keystone probiotic discussed (DISCLOSURE: the guest is involved in developing/researching this product; this is descriptive, not an endorsement or product recommendation, and some cited research was described as not yet published)
The 5R functional-medicine gut protocol — Remove, Replace, Repair, Reinoculate, Rebalance
Fiber & diet — psyllium husk; a diverse, phytonutrient-rich, Mediterranean-style diet as “fuel” for keystone microbes
Supercentenarian “M116” (Maria) — the ~116-year-old whose microbiome was studied (as discussed; verify before citing)
The young-mouse / old-mouse microbiome transplant study — an animal model, not proven in humans
Microbial ecosystem therapeutics — extracting screened microbes from a healthy young human-donor pool (distinct from fecal transplant)
“Longevity Switches” — Dr. Druz’s forthcoming book
Heartwell AI (heartwell.ai) — Holistic Heart Centers’ personalized cardiovascular-risk tool

Holistic Heart Centers

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HeartWell.ai — AI-powered cardiovascular risk assessment
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