StarTalk Radio - The Gut-Brain Connection with Emeran Mayer

Episode Date: March 21, 2025

Is your gut controlling your brain? Neil deGrasse Tyson, Gary O’Reilly, & Chuck Nice dive into the gut-brain connection, GLP-1, and how this connection plays a role in conditions like anxiety, IBS, and even neurodegenerative diseases with gastroenterologist Emeran Mayer.NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free here:https://startalkmedia.com/show/the-gut-brain-connection-with-emeran-mayer/Thanks to our Patrons Sebastian, micheal bulger, Brenna C, Greg Neeley, Kathy Han, Elizabeth Hoecker, Sandra A. Segovia, Roy Rudder, Badri, Kevin Cromarty, Javier Toscano, Steven Tankard, Paul Goggin, Manjinder, Clare Martin, Kiru, Christopher Deutsch, Pat the builder, Christian Martel, Adrew Hernandez, Chris Talbot, Austin Kirkland, Elihu Del Valle, matthew Scofield, Ed Labaro, Eric Kennedy, Max Arnold, muffy7, Jomo, Visva Visva, Stephen Nicoud, Joseph Jeries, Mohammed Saif, Xebec, Fekeetsa, Neeraj Chadee, Suzanna Alexander, Balkrishna Heroor, James Williams, Andrew Perez, Christopher Pence, Ryan A, and Matt Parsons for supporting us this week. Subscribe to SiriusXM Podcasts+ to listen to new episodes of StarTalk Radio ad-free and a whole week early.Start a free trial now on Apple Podcasts or by visiting siriusxm.com/podcastsplus.

Did we just take one to the gut? We did. Look at that. I see what you're... A gut punch of a show? A gut punch of a show. How many more puns can we come up with? They will leave you with food for thought.

Another pun! I love it. Okay, you guys just got to tune in to figure out what we're talking about. The mind, body, gut connection coming up on Star Talk. Welcome to Star Talk. Your place in the universe where science and pop culture collide. Star Talk begins right now.

This is Star Talk, special edition. Which means I got Gary O'Reilly, Gary. Hey Neil. How you doing man? I'm good. Chuck, good to have you man. Good to be here, of course. Alright, today I'm checking out this subject.

I love it. Okay. The gut brain connection. Ah, some people's brains are the gut. Such a... Oh, we went philosophical straight away. Yeah. So Gary, tell us why, what's going on in this episode.

Okay, so we've had everybody for our lives tell us they've had a gut feeling about something. Gut feeling. Yeah, and then we've seen people under stress die. They don't say I have a brain feeling. No, this is exactly it. And we've seen people who are under stress dive into the fridge.

We've seen people who are depressed, not want to eat at all. And then we kind of work out that our guts are not standalone systems within our body. That there is actually a direct gut-brain connection. So that gut feeling may actually be a fact, not a fictional imagination of somebody. Now imagine, just imagine this, that every emotion you have has a mirror image within your gut. Oh, that makes sense.

They call it hangry, don't they? Don't they just? I'm hangry. I'm hangry. And they hear, spoiler, pun coming, that is obviously our food for thought. Ooh, I see what you did there. And now it's our time for an expert.

And now I'm hungry. There you it's our time for an expo. And now I'm hungry. There you go. I see what you did there. Okay, we have with us here in New York City, visiting us at the Hayden Planetarium, right here in my office, a gentleman based at UCLA. We have Emron Meyer.

Yes. I think I said your name correctly. You're a medical doctor at UCLA. You're a gastroenterologist, which is a lot of syllables to say you're a gut man, I think. Am I correct? Is this Scrabble winner?

You're also a neuroscientist. You hardly ever see those two in the same phrase, because your brain and the gut. More increasingly you do now. Maybe so, all right. And you're also an author. And the books, I got them here, very simple. It's just Mind and Gut.

Mind-Gut Connection. Mind-Gut Connection. That was in 2016 with HarperCollins. And then Mind-Gut, and you added a word. Immune Connection. Immune Connection. Ooh. So the mind, gut is taking over the body here.

Yeah. All right, we'll see what that can take us. And so my notes here say you're also a documentary filmmaker. What's up with that? Yeah, I almost didn't go into medical school because I was fortunate. A retired businessman invited me several times to accompany him as a sound assistant

to places in New Guinea and on the Orinoco River to the Yanomami Indians and very formative experiences. And the nice thing is I can now reconnect back. I mean, I was just a first year medical student, had no idea about any of the things I know today. These people that we visited and lived with, the Yanomami, are very interesting group of people that have the healthiest microbiome on the planet.

So, found it out. And how do you- They poop three times a day. I was going to, well, that's where I was getting, I was like, how exactly did we determine that? That they have the healthiest- Are you digging into their poop in the forest? So there was a scientist, Gloria Dominguez,

married to a very famous gastroenterologist and researcher, and they had the interest in studying the microbes of peoples around the world with what they call the vanishing microbes, you know, losing microbes. So they went to the Yanomami and did the most elaborate analysis, didn't do it there, obviously took the samples. And it turned out that this microbial system that these people had is the most diverse

and richest of anybody on the planet. They must have thought you were crazy. Can I have some of your poop from my lab? I don't know, I know some places in New York where you get charged extra for that. So just to finish your your resume here, so you're a professor in the departments of medicine, physiology and psychiatry. So you're a professor in the departments of medicine, physiology, and psychiatry. So that's an evidence of your breadth and what you brought together for your studies.

And it's guided me. So my career has led me down this path at starting in the gut and then always having an interest in the brain and the nervous system. And at some point I said it was necessary to connect to these other departments. And that's at the David Geffen School of Medicine at UCLA. Let's just get this started.

What is the brain-gut connection? And if I understand the timeline correctly, nobody was really talking about this until your books came out. Oh, really? So you wrote the book. You're a pioneer. On the brain connection.

It was a surprise to me because I've struggled in my professional career for literally decades to get this concept of brain-gut connections accepted as a major factor, not just as an epiphenomenon, but as a major disease factor in like inflammatory bowel disease and irritable bowel syndrome, many of these what we call functional gastrointestinal.

That's the IBS I guess. I hear it all the time now. Yeah, on TV commercials. And so it was like, it was kind of amazing that enthusiasm that gradually developed after the book, not the first year, it was not really popular the first year, but then gradually it picked up and now if you go online, online, every second word is gut health

and brain-guts connection. You hear about it all the time now in more of a cursory fashion. There's not a lot of in-depth talk about it, but what is your gut? Well, I mean, the gut, I would say, is after the brain, the most complex organ we have in the body. It's not just a digest, it's a tube from the mouse I mean, the gut, I would say, is, after the brain, the most complex organ we have in the body.

It's not just a digest, it's a tube from the mouse to the anus, and for a long time, digestion and absorption and storage of waste has been sort of the main focus of interest. In the meantime, we know that 70% of our immune system is embedded in the gut. Big portion of our hormonal system, endocrine system system is embedded in the gut. A big portion of our hormonal system, endocrine system, is embedded in the gut.

There's a separate nervous system in the gut which is called the little brain. Mike Gershon here from New York, Columbia, sort of being a pioneer in describing and popularizing that concept. Wait, wait, so some people literally have their brain in their ass? Is that what you're saying?

Yeah. But if you... Yes. I know, we probably don't know the same person, but we know they're like that. Yeah. But to sort of ramp up the answer, all these systems in the gut

are interconnected with each other. So the gut is like a brain. So who's talking to who? Is the brain talking to the gut, or is the gut talking to the brain? No, first, to the gut or is the gut talking to the brain? No, first within the gut we have the immune system and the, you know, the micro cells that live in the gut and the nervous system in the gut. They all communicate with each other all the time. So you don't know it, you know, right now if I could look inside of you

with the right lens, you know, I would see all these things interacting and talking to each other. Then you add the brain to it. And it's the same thing. There's a bi-directional communication going on 24 seven, even when you sleep always anything that happens at the brain level, the areas that earlier has a mirror image in the gut, which we don't see. You see it on your face. So if you're angry, I can see it on your face.

We can see that the gut contracting when you're angry, but also a lot of things that go on in the gut generate emotional feelings or most of it, 95% doesn't become conscious. So that's the thing about the- So we have receptors and transmitters. I can say it, but what are they? How are they activated?

How are they working? Obviously, not emailing each other, but... And just to clarify, when you said it's not conscious, it means, if I understand that, it means you will have a feeling and you won't know why, but you'll then act on that feeling. And if it's your mind gut connection controlling it, it means you have behavior that's being commanded to you by microbes that you need a microscope to see. Yeah, but what I want to say is for a lot of people, they're not aware of this.

They're very oblivious to their body. They just have urges. Yeah, yeah. But like a sensation that everybody knows is satiation, hunger and satiation. Absolutely. So these are the most basic gut feelings that people have. And it's so funny you say that,

when I was younger, my mother used to say, I would eat and then I'd say, I'm still hungry. And she would say, just wait 10 minutes and your stomach will talk to your brain and let it know that you're not hungry. We'll catch up with the, yeah, your brain will catch up with your stomach. And I don't think,

I don't know where she got that from, but damn if that's not the case. Yeah, a lot of people have lost that mechanism. You know, like a big part about obesity is that that signal that comes from the gut, this GLP-1, this molecule that everybody talks about, is produced in cells in the gut and goes to the hypothalamus in your brain

and tells your brain to stop eating because you're full. A lot of people have lost that mechanism, that feedback. Why that is, but it's not clear. So what do you now do with mega doses of this hormone? Right. 100 times higher than what the gut produces. These are the GLP-1 injections that everybody sees on TV now, right?

So that gives you that sensation, but you know, in a- GLP-1, excuse me, but a pharmacist sitting here among us. We can't help it, it's on every TV channel. That's true. And by the way, it's on every TV channel. What? That's right. And by the way, how do you think I lost 20 pounds? No, of course not. So you're saying, so this, I didn't know this, so this chemical that we see advertised 100 times a day,

is that molecule, but heightened, to create this sensation that really your body should have been producing all along. Yeah, it does a lot of other things. We don't know many of them because now all of a sudden, it seems to be effective in substance use disorders. So people who take it find that their urge to drink. So people who have an alcohol abuse problem,

they stop abusing alcohol. They're like, yeah, I just didn't want to drink. Yeah. And it's kind of ironic. When I first came to LA as a research student, I studied that hormone, you know, and also it's sibling called GIP that there's another medication that has that.

And at the time we didn't know, we were just excited to find all these substances in the gut. But nobody had a clue what they do. It took really literally 35 years or 40 years. I'm Nicholas Costella and I'm a proud supporter of Star Talk on Patreon. This is Star Talk on Patreon. This is Star Talk with Neil deGrasse Tyson. How was this received when you emerged with this idea that your brain and your gut are

connected in ways no one understood previously? Because as I understand medical school, you study the brain, you study the brain. You study the gut, you study the gut. And there's a siloing of the body where we are just bits and pieces assembled into one thing. And the idea that there's a connection will require that somebody in that mix

has interest in more than one aspect of the human physiology. Yeah, and I would say, you know, I've had a long-standing interest in college on in psychology and, you know, read all the stuff, Jungian stuff. So I came into medical school already with this background in, you know, in brain science.

With a perspective. Yeah, with the perspective. And I would actually say that the main reason I ended up in medical school, I thought I was going to go into psychiatry because then spending a month in a psychiatry rotation convinced me this is not what I wanted to do. Yeah.

Those people are crazy. Okay, nevermind. Okay. I might do it today. I'm not going to do it. I might do it today because psychiatry has moved on a lot. It really has, yeah. But I had a very open-minded,

a very charismatic mentor who really supported me in this, from the beginning. So he was interested in isolating all these molecules, like the GLP-1, not necessarily on the brain. And I said, can we combine this with the brain? And he was very open-minded, unusual. But most of my colleagues either ignored it, didn't find that interesting,

or then there were, like in the IBS field, for example, there were like really entrenched interests of people that say IBS is a gut disorder. Forget about the brain, you know. And don't you. So it's counterintuitive from the fact that when we're all kids, we learned that the hip bone is connected to.

It's as simple as that. The thigh bone. All the bones are connected. Like you would think that it would be just, you know. The gut bone connected to the brain bone. It would make perfect sense, right? So first thing we learn, we learn anatomy, day one. But it goes further than that.

I think Western medicine, very successful obviously in many aspects, but it is based on a reductionistic view of the body, not an interconnected, not a systems biological. And it's gradually changing from the, there's a couple of developments, like there's an entity now called functional medicine, non-scientific entity, but also in science,

there's more and more scientists that think in systems biological. Interconnectivity between the systems. So it will take another 10 years, I think, and then it will change. I mean, they'll catch up with you. Yeah. How about that?

Yeah, all right. So we spoke about GOP-1, but you've got cortisol and serotonin, the stress. Yes. I suppose we love eating. We have an experience when we eat certain foods that maybe, you'll tell me yes or no,

with serotonin being released in the gut or dopamine and then the cortisol. Like I say, you're diving into the fridge because you're under stress and you're going for the sugars or the fats or whatever it is. How long did it take us to work all of that out? And we've got this image of the person who just broke up with their loved one. That's a gallon of ice cream.

How to get that. Watching a sad movie crying. What's up with that? What's up with sad movies too? The gut likes Haagen-Dazs ice cream. Or any other ice cream. So there's some very smart people who've worked in this area. So surprisingly it was never really identified

as the brain-gut connection. You know, they always talk about appetite and stress and substance use disorders. But it never really became sort of an essential part of it. But that's really how it started. You know, we knew these things for quite some time. Very good scientific studies support it. But it's not really become a specialty, you know. Because of this dominant paradigm, I

think. Right, yeah. So going back to Chuck's insight into anatomy. The knee bone is connected to several other things in the body. The gut bone is connected to the brain bone. So how is the gut connected, A, to the autonomic system? And then the vagus nerve, spelled with an A, not an E. And what does the vagus nerve do?

Because we've heard about it. I couldn't tell you actually where it is in the body. It's right here. Yeah. The vagus nerve, spelled with an A, not an E. And what does the vagus nerve do? Because we've heard about it, I couldn't tell you actually where it is in the body. But. It's right here. Yeah. The vagus nerve? Okay. Above your clavicle, where your neck is, and it runs down.

Why are you telling me this and not the good doctor? All right, Doc, tell us, where's the vagus nerve? Where you said. Exactly. Yeah, so the vagus nerve, first of all, it's a bidirectional pathway. It's like a bidirectional freeway. Most of the traffic goes from the gut to the brain, to the brainstem, and then to higher

emotional centers, and 10% goes the other way. So for example, to stimulate the acid production in your stomach, that's a vagal phenomenon. That's why people used to cut the vagus in your stomach. That's a vagal phenomenon. That's why people used to do, cut the vagus nerve for ulcer disease. This was a dominant, which is amazing when you think about this is only like 30 years ago that we have absolutely no understanding of. It's like cutting off your foot

because you have an ingrown toenail. Exactly. That's insane. That's comparable. So where on your body is the vagus nerve? It goes down from your brain stem, down your neck. Just like, that sounds like just what Chuck and I said. Did Chuck say that nine seconds ago?

Yeah. Just tells you no. Okay. But what's important is to realize, so the vagus nerve has branches to all your organs. It monitors every organ function 24-7. The ones to the gut have received a lot of attention because we were always wondering why is 90%

of the traffic going from the gut to the brain there's not that much happening that the brain needs to know. So now we know there's all these receptors on the vagus nerve for serotonin, for these, for GLP-1, for GIP. So disproportionate, what we call afferent or sensory signal to the brain is related

to this complexity that goes on in the gut and the signals it gets from the micro. It's a processing hub. Yeah. So I'm still confused. How does any of that relate to your immune system? So the immune system, as I told you, more than 70% is located in the gut, sandwiched between the layers.

Seven zero. Seven zero. Wow. Sandwiched between the layers of the gut and vehicles communication to the microbes in the gut. Microns away, you know, so how nature could engineer something like that as a potentially deadly influence of microbes.

So a micron is a millionth of an inch. Yeah. I mean a millionth of a meter, I guess. Yeah, of microns. A micron is a millionth of an inch. I mean a millionth of a meter, I guess. Yeah, of a meter. Right, so that would be a thousandth of a millimeter would be a micron, yeah. Yeah, so the immune system is very close to the vagus. Some of the sensor nerves go into this immune system

in the gut, and they pick up signals that the immune system produces, like cytokines, for example, are best studied, and that has all kinds of effects on your behavior, you know, like cytokines, fatigue, chronic pain, some of them. So. Oh yeah.

All right, so I got to come at, so pause. Then, what is the urge that people have to, what do you do when they clean out the colon? A cleanse. A cleanse. This is urge to get it all out. Oh, I can answer that for the doctor.

And or people prepping for a colonoscopy, they're cleaning everything out. So all these microbes that set up shop to communicate with the brain, they just flow out your body just for the benefit of one of your colleagues to look up your butt. Okay? And so, are we destroying this hard-earned microbiome

every time we get ready? Oh, Chuck had an answer. What's your answer, Dr. Chuck? Okay, so here's my answer. For the cleanse, that's bullshit. So that's the first answer. For the cleanse, that's bullshit. So that's the first answer. That's human shit, but yeah.

No, no, I'm saying the actual cleanse itself. I mean, I know it's supposed to get rid of your stuff. That was a joke. Oh, I'm sorry. Wasn't that a good joke? Oh, I thought you were saying it like, okay, nevermind. You said it's bullshit, no, it's human shit. You said no, it's human shit.

Yeah. See, we missed the no, because I would have laughed at that, because that's funny. Okay, excuse me. I'm sorry, I missed the no. But the colonoscopy, that's so that they can look at your intestinal lining, and the good stuff

that you need is in the walls of your intestinal lining. So cleaning that out so they can look at it, you're not getting rid of. Yes, there are two answers from my side. The first one, I would contradict what you said. Oh, you think it's real. So, well, you know, Ayurvedic medicine for thousands of years has propagated these colonic lenses.

All right, so what is the benefit? Because everything that I read says that the benefits are negligible at the best, okay? Unless, wait, that would be health benefits, but suppose you just feel better. Doesn't that count? We're talking about how you feel. I feel better when I punch a puppy.

Does that make it, nevermind. I'm sorry, did I say that out loud? Okay, anyway, tell me why it's good. Before I get arrested. So for a long time, this has been dominated or driven or motivated by this concept of cleansing. So humans are obsessed with cleansing. They spend a lot of money on cleansing,

so not just cleansing the colon, but a cleansing diet. In not 19th century Europe, but in modern times, yes. Cleansing. But it's become very popular again. You talk about your ancestors. I know, I need to dig. You take a bath once a year and only if necessary. Yeah, but it's our birthday, you've got to celebrate.

So with microbiome science, there's a certain potential explanation why people have been doing this over thousands of years. Why? Well, because it reestablishes a balance within, you know, within your colonic microbiome. Okay. It has not been studied scientifically, but it certainly... You're saying it's feasible though. So even though it's not, even though we don't have empirical scientific peer reviewed studies,

it's a feasible concept that this could be the case. It is, it is conceivable and it's, so the blueprint for your microbiome doesn't disappear with that. So you cleanse out the population, the blueprint is there and it can read the body can reconstruct the... Okay, so it's a jumpstart. Yeah, jumpstart. Alright, fine. You have changed my mind on this. Stripping off a layer of pain and then just it re-evolves itself to bring in a new layer of pain that's nice and shiny. So if our microbes are not important in our gut, over evolution,

we'd have got rid of them. It's like sleep. We are never more vulnerable than when we're asleep, right? Yet we've not evolved to do without sleep. Why haven't we evolved to do without microbes in our gut? What? How? How come this? Because they're the OGs. They're the original life forms on this planet. They've been here for four billion years.

You know, three and a half billion. Can't get more OG than that. That's for sure. Three and a half billion before. Original gut. You know, beautiful. Oh. Nicely done.

Nice, thank you. But it's been the most successful evolutionary development because every organism today from the cockroach to the butterfly to humans has a microbiome, a gut microbiome. Whoa. There's not a complex. So there's a number I calculated

and it just freaks people out that if you go to your large intestine and take one centimeter slice through it. Just one centimeter. One centimeter, that's four tenths of an inch for those who, for Merck. For Americans. For Americans.

Merck, that's right. I'm bringing in that metric crap over here. Talk about Merck, boy. Talk to me in inches. Talk about millimeters, centimeters. That four tenths of an inch lives and works more microbes than the total number of humans who have ever been born. So that we think that we're in charge,

but we're just a darkened anaerobic vessel of fecal matter for microbes. We're an Uber ride. That's what we are. We're an Uber ride for microscopic organisms. For microbes. We're an Uber ride. That's what we are. We're an Uber ride for microscopic organisms. So microbes. Yeah, I read something recently in a book by one of my favorite scientific authors,

Antonio D'Amazio, on this comparison, the early life forms, which had a lot of intelligence. I mean, these microbes on the planet must have a phenomenal amount of intelligence collected over three and a half billion years. But they couldn't do long division, so. Yeah, but I mean, they don't have a mind, and obviously they can live in homeostasis

with each other and with the world. Their main benefit is that they now can connect to our brains and can influence a conscious entity. So they do have a mind. So if we've got the original gut microbes, the OGs as we now like to refer to them, three and a half billion years, they've invented their own language. They've had to have their own alphabet of sorts. So how are they communicating with us from their little hidey hole in the gut?

You know, they have millions of genes compared to our, you know, meek number of 10,000s. In these genes is stored all this information, how to build these molecules, how to use them. So their language is basically stored in their genome. So their own history of three and... Yeah, yeah. Heavens. Brilliant, three and... Yeah, I know, I was about to swear before I got to the B.

Billions and billions, okay. So then when they settled, the first microbes settled in these floating tubes of the first marine animals, they interacted with this floating tubes of the first, you know, marine animals. They interacted with these floating tubes and there's something called lateral gene transfer, that they transfer some of these genes that they had about their language into these animals. And, you know, fast forward, there was the first version of the so-called little brain of the gut or the enteric nervous system. And then with animals developing heads,

becoming polar organisms, some of the same information about language was transferred to the brain. What is a polar organism? Having a head and the opposite end, whatever that is. Okay, okay. Yeah, so our language, our ability to think comes, uses the same building blocks as the microbes developed

over billions of years. That to me is one of the more fascinating ideas. Incredibly fascinating. So seeing as how we have the gut-brain connection, we've seen microbes have their way of communicating with us. Is this the superhighway that is used for psychedelics? Because we're ingesting, and yet everything's going off up here in the brain,

but not so much down in the gut. So is this a sort of exploration here? There's a lot of things going on in the gut that we don't know yet. Like serotonin plays a big role, as you know, with the psychedelic experiences, activating a particular serotonin receptor, the 5-H2A receptor, which is in the brain.

So these psychedelic experiences seem to, many of them seem to be related to that receptor in the brain. Now the same receptor is also in the gut and on microbes. And we don't know what effect this actually has, but one is also- And it can't be an accident, right? It's not an accident.

It's a co-evolutionary thing, right, okay. So is the mind desperate to try and expand? And that's why it's so active to find something like these psychedelics, and then just whiz them up to the brain? Yeah, I mean, humans have probably used psychedelics for a long time. Long, long time.

Long, long time, And based on the experiences, probably initially by accident, that they ingested a mushroom and all of a sudden saw the world. Is that the sort of, when you talk about an evolution, just by accident eating a mushroom, is that sort of the beginning of a stoned ape theory of evolution?

That's a phrase, stoned ape? Yeah. What is the stoned ape? I mean, I've been to the zoo, but I've never seen him, you know an ape I would just love to sit there and watch a chimpanzee tripping its balls off I would love that but I haven't had the pleasure of in out in the world I'm guessing they'll stumble across a mushroom be curious and eat it and go whoa

So isn't the basis of where Gary's coming from, why do we have receptors for psychedelics at all? Unless it was the purview of the microbiome that delighted in it. Yeah, that's a really interesting question. I can't really answer it. I can only say partially based on personal experience. I guess I can say this here, even though it's not recommending for people to do it.

I am, I'm recommending for you to do it. The good doctor here can't. I'm letting you know, everybody should do psychedelics. I mean, I can't do it for legal, medical, legal reasons. Assume me, please, but do it. But the experience that you have, and everybody says it's a universal human experience. It's not that one person gets

this realization of the interconnectedness of yourself with the environment, the planet, like you get a totally different paradigm. Oh yes, without a doubt. So you, Chuck, you. Oh God, yes. You missed a few shows a few while back. I did.

Because you. I traveled to Costa Rica to do Ayahuasca for an entire week. Wow. And I will tell you that it changed my entire life. It changed my perspective on everything. Did you get funnier? Not at all. And that, and you know what?

While I was in my, one of my, while I was in one of my transmeditative states, Mother Aya came to me and said, I can't help you with the funny son, I'm so sorry. Okay, so just to be clear, when you did this, it was a fully supervised activity. You know, they are licensed, they're fully supervised, and they have medical staff on hand. It wasn't somebody who sold you something on the street.

No, nobody on the street. And you did it in a back alley. And by the way, now that I do not recommend, I say please find a professional and have somebody there to supervise, make sure that there's medical staff on hand. Do not go to somebody's house, okay? And do not go to some dude with a ponytail who's just like,

dude, I've been a shaman for like so long now, and I would love to turn you on to the universe. But if he doesn't have a ponytail, it's okay. And it's not a party drug. No, it's not. If you're looking to get high, don't do it, because it's not that kind of high. Yeah, so like one of my speculations is,

I mean, again, partially based on self experience. So there's different phases to the psychedelic experience. There's the initial rush that you get and with a lot of visual and auditory experiences. But then it has this long lasting effect. I mean, at least 24 hours that you notice it, if you pay attention to it, with your ability to communicate and to talk

that you've never talked like this before about yourself and your emotions. And then even past that one experience, a lot of people say that one experience, just like you said, can have a life-changing effect because from now on, you're going to look at the world differently. So that's easy to understand knowing that it interferes

with brain neurosynapses. How does that connect back to the gut? Ooh. Well, the slow effect, you know, I mean, the thing that, what happens in your brain initially is a fast response. It's being absorbed in the small intestine.

Oh, because you ingest it. Yeah, you ingest it. And it's gotta get through your, so, it only gets to your brain as the microbiome allows it. Right, true. But it's the part that is not absorbed in your small intestine, which happens immediately after ingestion.

It's the part that goes down to your colon, and then these longer lasting effects, I would not be surprised if they're mediated by microbial, you know, they add things to it. When they stimulate it with the 5-HTA 2A receptor, they produce other molecules that then create this long-term experience.

All right, given that there's this connection, there's so many other psychological features of human behavior, some good, some bad, some failures of our psychological profile, neurological diseases, this sort of thing. How much of that can we blame on our microbiome? Our current knowledge is pretty much based on what we call association studies or correlations. You take a big population of people that have a particular diagnosis and then you look at their gut microbiome and it's different.

You have to even know to do that as part of the study, right? But it doesn't prove causality. That's the thing. So I personally think of, I'll give you a few examples. I think anxiety, in my opinion, I've studied this pretty intensely for the first part of my career. We know so many mechanisms in the brain that, you know, and the effect of early life adversity

that predispose you to have great anxiety. So we know so much about the brain that, you know, and the effect of early life adversity, that predisposes you to have greater anxiety. So we know so much about the brain mechanisms that some people try to propose, you know, it's your microbes that cause the anxiety. Has any of your research gone into diet relation to Alzheimer's development? Yes, we're part of a big US-European consortium on Alzheimer's disease funded by the NIH. There's definitely pretty strong evidence that- It's the NIH National Institutes of Health. The National Institutes of Health.

Say goodbye to that. Thank God we have it. Thank God we have it now. What time is it? What time is it? Let me tell you something. Now you sound like Flavor Flav. Yeah. Yeah.

Yeah. Yeah. And I would say there's pretty solid evidence that again, what we call dysbiosis or altered composition of the gut microbiome plays a role. And there may be heterogeneity, you know, it's not Alzheimer's is not one disease, maybe different pathways.

Yeah. Yeah. Diet and what we now have, you know, it's become sort of the magic word, systemic immune activation or systemic inflammation is clearly one of the main risk factors for not just Alzheimer's, but also all the other ones, like Parkinson's. But Alzheimer's is also, it's interesting.

So anything preventive for any of these chronic diseases, you want to go to what's referred to as an anti-inflammatory diet, which basically. That's an emergent awareness of our health. Yeah. Is that butyrate, anti-inflammatory, the phenome? Yeah, and butyrate is from the- The polyphenols and those sort of things, yeah.

A largely plant-based diet. Once you have Alzheimer's, severe symptoms, there's evidence that a ketogenic diet, which is not a good diet for the average person because it starves your microbes, but in that case, it's beneficial and there's one disease entity, refractory seizures in young children, who are ketogenic diet is also.

Oh my God! Ketogenic is basically protein all the time. Fat and protein. Keeping your body in ketosis, a state of ketosis. Right, right, which means you don't have access to sugars or any carbohydrates. Correct, so your body basically uses the fat. And of course, presumably before we were agrarian, our ancestors, they ate dead animals, right?

Or berries, of course, if they could find them. But they were, the caveman diet is this, correct? Well, but going back to my personal experience on the. As a caveman? Right, you have to cite that. Oh no, it was? That's a caveman. You had to say that. No, it was just hanging there. It was just hanging there. I didn't do it.

Living with the Yanomami on the upper Orinoco River. So they're surrounded by animals, by birds, by fish, by big mammals. They only eat a very small amount of animal products. They mainly eat tubers and berries and plant-based stuff. That's why they have the healthy microbiome. That's why they have the healthy microbiome. And that has been studied all the way,

as a colleague of mine at UCLA, Elaine Chauch, all the way into the production of GABA, this inhibitory neurotransmitter in the brain on a ketogenic diet. That's sort of like Valium. It sort of tones down the nervous system. How much of this is us really knowing a lot of it, or how much of this is us just beginning to understand?

I know you've been doing this research for decades, but just how much more of this do we not know yet? What can we look forward to? I think we're just scratching on the surface. No, really? Yeah, I think, well, I was just thinking about these millions of genes that the microbes have. We only know as-

Why don't they have more genes than we do? That ain't right. Yeah. We've been around a little bit longer. Or is it the collection of genes represented in the diversity of microbes that you're referring to as millions of genes? Yeah.

Okay. So if someone prepping for a colonoscopy, they just got rid of the entire population of microbes. So why, other than the value of the exam to prevent colon cancer, how do you get back your microbiome if it's all in the toilet? It comes back fairly quickly. You know, I would say... Where's the recipe?

Who's... Oh, so the blueprints to reassemble it is in your... It's inside your dining. Why don't... I'm asking the medical doctor here. Well, I'm telling you. Did I ask the two of you? No, but you got it anyway. Yeah, so you need to know, so.

Okay, so you're saying we are chemically equipped to reproduce the microbiome that is suitable for us. So there's a form of colitis, or a very serious form after antibiotics, where you basically just destroy your microbiome. Oh, because the antibiotics, while it's getting rid of whatever was your condition, it's biotics and you're just killing everything.

So it's called C. difficile colitis, that's the name. So one therapy that is very effective is a fecal microbial transplant. It's the only disease where that works. A poop transplant. It's a poop transplant. So whose poop are you taking? Oh, you had to ask?

I'll tell you this, not dog poop. So there's now, people have identified donors that are free of any disease, any family history of disease. So, and that have a diverse healthy microbiome. So these are the donors. So one of the most effective therapies is to get one of these transplants, these poop transplants. And so for a while then, the person who got this transplant

has the microbial composition of the donor. Because he or she himself didn't have it. But if you look at this a few weeks later, a few months later, the person's own microbiome is being reassembled. And the reason it's possible is because the microbes are not just floating inside the lumen, the inside of the gut, but they also inhabit

the mucosal lining, and that's probably where that information is stored of the blueprints. And that's where it comes back. I did say that earlier, but that's okay. No, that's just... I don't need to be right, I just need to be funny. But if you're right and funny, that's even better. I guess right, yeah.

So what about advertisements for gut ailments? And every time I see one, I say, do I have that? Or could that happen to me? And one of them shows up a lot is IBS or Irritable Bowel Syndrome. Do we know the cause of that and can gut health fix that? Yeah, so this is something that myself

and my group have studied for, you know, like I would say four decades. You're failing badly because people still have it. Yeah. Get back to work, what are you doing here? Well, fortunately, finally, after 30 years of writing articles and review articles on it, it's basically called a disorder

of altered gut brain interactions. Ooh, they did bring the brain in. How about that? Finally. And it's the most effective therapies are brain targeted therapies, meaning simple relaxation techniques, mindfulness based stress reduction,

gut directed hypnosis, cognitive behavioral therapy. They're better, more effective than any of these medications. Now you're getting all new agey on this. No, no. So how was this received by, quote, Western medicine to have these? A lot of resistance. and also the pharmaceutical industry.

Of course you need a pill, they need a pill. They need a pill, yeah. You can't meditate a pill. So you've got, I mean we're getting inundated with supplements, we're getting inundated with probiotics. I mean is this. Yeah, probiotics too. There's all these, you know, eat this yogurt because it's got the bacillus, the active microbes, do we really need that?

So the official organization of gastroenterology has published, you know, they always publish these statements, these expert statements, and they said there's not good enough scientific evidence to actually recommend probiotics in general as a treatment for IBS. However, there are patients who benefit, and there's also, there's different types of probiotics.

If now go on the internet, yeah. Yeah, it's a whole industry. Yeah, it's a whole industry. And like when I wrote my book, somebody came to me who was a retired Hewlett Packard engineer who said, do you want to be my partner? I want to start a probiotic company. So we just go to these big warehouses and get our organisms

and then we package them and then market them. So that's a lot of people have. You said no and he's a billionaire now, is that what you're saying? I have not seen him since then. Okay, no, no. All right, so there's a lot on the table right now, and we're inundated by ads that are telling us one thing or another

about medicines that are being put forth. What would you say is a best practice going forward? Not that you're prescribing for an audience that is surely diverse, but what kind of things should we be aware of as we put food in our pie hole? I love that word. Just a glimpse on your diet. Yeah, that's...

Stop that. Don't judge me because I like pie. So first of all, I would say it's not just the food. You know, it's the lifestyle. The food is a big part of lifestyle. Same with the Mediterranean diet. I no longer call it the Mediterranean diet, but the Mediterranean lifestyle.

If you go to Italy in summer, you will experience that the social interactions and the, which is a big part of it. You know, like all the studies. Does it not go back further than just lifestyle? Being around people. Does it not go back further than that to the soil? Where our plants come from and the animals eat that,

then it comes down the food chain to us. Yeah, so like the awareness of why your gut health and that the animals eat that, then it comes down the food chain to us. Oh wow. Yeah, so like the awareness of why your gut health may not be optimal is key to start out with, because then you realize it's not just what you eat, but where it's grown and how it's grown and how do you eat it in which context. That's easy to say, but suppose I don't care about any of that

and I do poop regularly, what should I be worried about? And I don't have mood swings, I don't have IBS. So does that make me rare on this spectrum of gut biome issues? It seems right now, you know, all of a sudden, since this has become acceptable as a topic for dinner parties, which was not the case even 10 years ago,

it seems like everybody now has, like 40, 60% of the population has some kind of a poor gut health. I'm not sure if that's true or not. Wait, but the people you studied, you said they have the best gut health in the world. What is it about them that manifests this fact? Do they live longer?

Do they never have diarrhea or constipation? What is the metric for you to arrive at that conclusion? You know, for these people. Because we should just do what they do, if that's what you're saying. Well, if you lived with them, you would realize, we can't go back, you know, there's no way back. There's no way, there's no way back. There's no cable, there's no streaming.

I'm not eating leaves and grubs and- Grubs? Yeah. Tasty grubs, I'm not tasty. But what we know about them is, so they have an interesting thing. They have a lot of little wars and the wars are invading another village

to get women from other villages and they do this to prevent inbreeding. So this is part of their culture, that they always- They could just have a dance, you know? Just, hey everybody. A social. Yeah, just come on over here, we're going to have a little dance,

y'all meet one another, you know. Anyway, so- Sorry. So a lot of them die early because they're bitten by a snake or eaten by a crocodile or- A lot of good, the healthy gut biome did for them. But if they don't have. But that crocodile has the healthiest gut

of all the crocodiles. Yes, and that's why crocodiles smile. But here comes the interesting part. If they don't die early from one of these accidents, they live into their 80s without any medication. No medication. Wow. And no medical system.

And no medical system. That is impressive. And no medical assurance or anything. Well, yes. Well, we don't have that here either. So, let's be honest. This is America. We do not have healthcare.

All right, it's an illusion, people. Don't get mad at me. Vote differently. Okay, all right. So, you've spoken of a mixture of traditional Western medicine and lifestyle, a diet, even sort of Eastern philosophies and ways of living.

Is there a way to sift the fact from the fiction for someone who's just exposed to all these ads and other YouTube videos? Someone who's just exposed to all these ads and other YouTube videos. Someone who's seeking guidance and not being inundated with all of this misinformation. Thank you. Very difficult for the average person, very difficult. Especially in today's media climate.

And it's going to get worse for political reasons. I think we're going to have to. Listen, don't blame me. I'm very healthy. I have a doctor who said that I have the best health that anybody could ever be. You know it, and I know it. So healthy, it's what I am.

Yeah, one of my missions at this stage of my career is really to provide that answer for people and the trust and the transparency. I think there always has to be, there's always has to be evidence supported. And the evidence could come from scientific studies, high quality, not, you know, five mice, and then claim that this is,

but it also can come from traditional success. I have this development criteria, somebody is stuck around for five or 6,000 years, there's gotta be something to it. You cannot just dismiss it. Turmeric is a good example. Yeah, so true. Anti-inflammatory, there's now scientific studies,

ginseng is another. So there's several things that I think you can, but then there's obviously in the middle of all of this is an enormous number of stuff that's placebo, and placebo is not a bad thing. If people feel better and they want to spend the money. People poo poo, I shouldn't use that phrase. People denigrate placebos, but if it works,

we should study placebos. Yeah, and so there's a lot of high quality research on the brain's mechanism to treat the placebo response. Is that another brain connection, the placebo, if your brain perceives that it's working? Yeah, so the placebo is a evidence-based therapy that the body does itself. It's the enemy of the pharmaceutical industry, obviously.

That's why it's badmau5. It's a wonderful thing. If you're a really good doctor and healer, you utilize the placebo response extensively. Interesting, isn't it? That's pretty wild, man. So, Doctor, what brings you to New York City? It wasn't just to do this show with us.

So, I have an invitation to this integrative health symposium that's going on tomorrow into Saturday. And I have a couple of one panel on IBS and one talk about increased stress responsiveness of people. Okay, especially stress is a buzzword. A killer. Of late. Yeah.

We're all stressed. Well, quarter's all in stress, very, and that's really linked, so. Well, welcome to the town. Yeah. And thanks for making some time in your schedule. And speaking of gut biome, don't eat any dirty dogs, okay? Hot dogs?

Yeah, man. Oh no, you need that. Yeah, you know, you gotta live here. See, the people who eat it every day. Oh, they every day. You can't be not from here and do it. It'll kill you. It'll kill you. Yeah, we built up a resistance. It'll kill you within the hour.

Right. But you go to the one with the dirtiest fingernails. That's what you do. That's it. That's the best one. That's the guy. Don't look at me like that. Thanks, Neil and team, it was a pleasure to be here.

Pleasure was ours, sir. Thank you. You guys are an amazing team. I've never done a lot of podcasts, but not like that. Thanks, Neil and team, it was a pleasure to be here. Pleasure was ours, sir. You guys are an amazing team. I've never done a lot of podcasts, but not like this. There's not too many out like this. Dr. Amoran Mayer with the 2016 book

Mind and Gut Connection, followed six years later by Mind and Gut. Immune. Immune Connect Immune connection. Nice. All right. It's all there and more. Gary, thanks for being here.

Pleasure. All right, Chuck. My stomach hurts. Stop. Well, go talk to your gut. Let's see what happens. My gut is feeling just fine. Good to know.

Thank you. So this has been Star Talk, special edition. Neil deGrasse Tyson here, as always, bidding you to keep looking up.