Dr. Emeran Mayer on the Gut-Brain Connection: Psychology, Mental Well-being & Diet

This episode is brought to you by Nourish Me Organics, your gut health superstore. Nourish Me Organics is the premier online store for all things gut health, including probiotics, prebiotics, natural health supplements, and home fermentation kits. So head to www.nourishmeorganics.com and use the code Happy Gut for 10% off in this episode. Crib Govenda, a seasoned food scientist and registered nutritionist, interviews gastroenterologist and neuroscientist Dr. Emren Meyer on the impact of gut health on our psychological and mental well being.

Hey, guys, cribbing governor from the Gut Health Gurus podcast. I've got a background in food science and today we have an absolutely amazing guest lined up for you. I'm super excited to have this conversation with Dr. Imran Meyer, one of the foremost experts when it comes to the gut brain connection and how the gut affects our psychology, our mental health. And this is like a topic that's so interesting to me. It's so important to me. So to get this opportunity to talk to Dr. Imran Meyer is an absolute honor. Dr. Imran Meyer, welcome to the show.

Thanks so much, Kriben, for the invitation and the exuberant introduction. I feel kind of embarrassed to live up to what you built me up here, but I'll do my best. And as you just told me, you know, we met, we first met six years ago at an early microbiome meeting and which I had forgotten. So it's actually nice to talk to you again.

It's my absolute pleasure to have you everyone. I'm so nervous to talk to you. I don't often get nervous with guests, but because you're such a hero to me, hopefully I can do justice as well and hold it together. And what I like to do at the start of the show is to get it straight from the horse's mouth. Who is Dr. Imran Meyer?

Well, I'm, you know, I'm a gastroenterologist. I've seen hundreds, maybe thousands of patients in my career. I've also have a career long interest in or pursuit of science of brain gut interactions in the last 10 years of brain gut microbiome interactions and about, I think it's now almost 10 years ago or close to that, that I came out with my first book, the Mind God Connection, and which actually influenced my trajectory. So I got this almost like this second hat now that I'm wearing, which is essentially communicating to the public to communicate all the scientific breakthroughs that are happening or have happened in, in microbiome science and in gut health, which I think the lay public has heard about, different sections. But then unfortunately the people that are communicating that information are not necessarily the scientists or the, the main player in the field. They're self appointed, you know, influencers. And so it's become a very prominent task for me to really fill that vacuum with, you know, evidence based, scientifically based information.

I completely hear you. Amazing introduction. Just to, to know your background in how prominent, prominent you are in this field. And I'm in complete agreement that we see this sort of social media landscape with all the different social media platforms and then you've got these influences coming up, well meaning as well, trying to get this message out there. But what I like to do is on this podcast to lean on the experts in the field, the people that are doing the research, and to get that information straight from you guys. And it takes a long time to go from a clinical study to the lay public. And what I'm trying to do is really close that gap. So 100% agree with what you're saying. And I think a good way to start this podcast is to be really relevant today. So it's, I'm kind of doing it opposite to how I normally do it, but let's talk about cutting edge discoveries and get that information straight to the public. So what is the most surprising new discovery about the gut brain connection that you've encountered in recent research?

Well, I would say for me the most surprising finding was really the, in the early days of this brain gut microbiome field were. So I've, I've worked on brain gut interaction scientifically all my career and you know, we were the first ones to use brain imaging to see what happens in the brain if you stimulate the gut and what happens in the gut when you stress the brain with emotional stimuli and stress stimuli. And we really thought we had figured it all out. We didn't think there was too many holes in that story. And then when the first papers came out from animal studies, from John Kryon and his lab and a few others in the world, I was very skeptical. I thought this was just not necessary, kind of naive in retrospect. I think these early findings, it took me a couple of years to really accept those and then do our own first human study where we demonstrate this effect of a probiotic mix on brain circuits in healthy women. So this discovery that there's something non human in our intestine that essentially uses the gut brain connection for its own purposes is that still and amazing. And you know, there's a lot of stories to that, why this is so exciting. And, and it doesn't, it doesn't really stop at the microbes in our gut because these microbes are, you know, are nurtured by the food that we eat. And the food, the plants particularly are greatly influenced by another microbiome in the soil. So we have this external mechanism were, you know, like the roots of the plants are kind of like the gut of our is, is our gut. So the roots interact with these soil microbes and then the soil microbes stimulate the plant to produce molecules that help the plants survive and defend the health of the plant. And then when we eat these plants, our microbes pick up these same molecules that their cousins in the soil stimulated. And then we, we pick those up and then they become health benefits for us, for our brain. I mean it's, it's, that to me is still one of the most amazing stories in this, in, in this field.

That's amazing. I completely agree, Dr. Mayer, that the, the soil in the gut, there's this kind of, this comparison between the two. The roots of us, of the plants going into the soil is like the enteric nervous system going to the gut. So there's certainly this amazing concept that nature's put together for us. And then my initial follow up question is how do you think the impact on agriculture and the development of agriculture has influenced the gut and then our mental health?

Yeah, so this is an interesting story. You know, people always say in order to feed the billions of people in the world, we need to expand conventional agriculture first with, with chemical fertilizers, which is done wonders. You know, it's prevented mass starvation in the world. And we've, we're totally accepted as a normal, you know, a normal part of agriculture now. And I'll come back to this, why this is really a mistake. And the second one is like things like hydroponic, you know, hydroponics to grow tomatoes and other vegetables in water without soil, it's another thing that's being celebrated. This is important to further expand our food production because in my opinion we don't really have to expand our food production. If we change the way that we don't throw away half of it of the foods that are being produced, there will be enough food for, for 8 or 10 billion people in the world, you know, but you know, people like these, these modern fans, I would say, not thinking about the consequences and just what I said a minute ago, why it's white chemical Agriculture, for example. So the plants are growing beautifully, they're getting bigger. The fruits and you know, everything is, is bigger. Go to the market, see these beautiful things. If you go to an organic, you know, farmer's market on the weekend, the foods don't look that nice. You know, they're not comparable. So but what happens the, the nutrients, the phytonutrients in these plants that are grown in an organic or regenerative organic soil, the concentration is much, much higher. And when we eat these, these beautiful plant products that are grown with chemical agriculture, it's like you know, plants being on, on, on steroids and, but they contain lists and lists of these health promoting molecules that they, the consequences on the one side that the plants are more susceptible now to diseases and to insects and pests and fungi and UV light. So we need to add this on top of these plants that are already grown chemically with, you know, with all the, you know, with all these fungicides and insecticides. And so this has sort of multiple consequences. Now ultimately it's particularly important today. So I'm promoting a largely plant based diet. But when you think about that, most of our plants certainly in North America are grown with, you know, with gmo. It's, it's not, it's not the, the gene modification, it's actually what we spray on these GMO produced products. And, and, and also, I mean the way that they're, you know, grown without this, this natural system of microbe, of soil microbes stimulating their, their health benefits. So we think we're doing something good for our health. But in reality these are depleted products. You know, these are not, they still have the vitamins, they still have other, you know, phytochemicals in it. But some key components like the polyphenols are devoid in this in these plants and that, that has been shown. So if you want to eat a real healthy diet, it's not just, you know, what you eat, but also where this food comes from and how, how it is grown. And I do know, I'm not following that very closely what happens in Europe, but I do think that many things are grown less with, with, with, with the kind of chemical agricultural means in, in, in Europe, certainly certain parts of Europe than there are in the US and, and, and Canada. Yeah, so it's so we, we, we need to pay attention to, as I said, not just that we eat enough 75% plant based foods, but also how is this food produced? Does it still have the input from the microbes that stimulate their own Health benefits which then transfer to us.

That's incredible. In complete agreement with everything you said. There's, there's a consequence for modern agricultural techniques. And I had no idea, this is the first I've ever heard about the, the polyphenol content of the vegetable being impacted by the way it's grown. So thank you for sharing that amazing information. So just to follow on, so by using these GMO type crops and then spraying chemicals like glyphosate or the, like, how does this impact the, the, our, our bodies and our microbiome when we consume that?

Yeah, so glyphosate, that's a good example. You know that when this was originally approved by the fda, it was based on in vitro studies on cell systems. And so glyphosate did not have a negative effect on these, on these isolated cells. And that's because, you know, human cells or animal cells don't have the enzymes that, that metabolize glyphosate into dangerous chemicals. And, but now we know that the microbes, some microbes do have these enzymes. So most of the time the microbes are doing positive things for us. You know, they, they make us, they make a lot of large molecular structures absorbable. So in general, I would say most of the things that they do are positive, but some of these chemical transformations that they do with chemicals that they have not seen in their own evolution, they may turn them into actually more dangerous, you know, products that then can harm us. And it's sort of amazing. And I don't know, I'm certainly not somebody, you know, believes in conspiracy theories, but I once had somebody come to my office very secretively and he, he told me that whole story how, you know, the, the, the agricultural lobby has kind of suppressed all these research efforts on glyphosate, more detailed studies, because today we could actually show that, that it's, you know, it's, it's. And, and as you know, there are big lawsuits against Bayer. You know, so there's a lot of work behind the scene to actually not make it public what this microbial process, glyphosate, can do to us harmfully.

That's incredible. That's an absolute bombshell. I had no idea that the conversion of these chemicals like glyphosate happen in the gut by the microbes to potentially produce negative adverse effects. That, that's stunning to me. I've never heard of that. So thank you so much for sharing that information.

I could add a couple of things to this. So this is what we Call. So glyphosate would be a cenobiotic, so a foreign product that the microbes encounter. I mean, the microbes had billions of years of evolution in the oceans of the world. So they became the masters of intercellular communication and communication with the, with the organic environment and then with the first animals. And, and they have accumulated all this wisdom in, you know, millions of genes, 100 times more genes than we have. But obviously they have not been exposed to all these modern chemicals. You know, I don't know how many, if it's 100 chemicals or a thousand chemicals that modern humans are exposed to, you know, just to name a few of them. The microplastics, for example. I mean, microbes in the evolution never encountered plastics, you know, but they do know how to break them down. And that's true about all the medications we're taking. You know, the microbes are sort of like a second liver. They can metabolize a lot of the medications, and sometimes it's, as I said, it's beneficial. In other times, like with the main Parkinson medication, they actually introduce this variability that physicians encounters when they prescribe these medications. In some people, it doesn't work at all. In other people, it has major side effects. Probably a big part of this is the role of the micro, the variable role of the microbiome on, on. On these, you know, on these Parkinson medications.

Incredible. And I'm sure there's so many other conversion processes that are happening in the gut via the microbiota and their genes that could be leading to potentially negative outcomes, but also positive outcomes as well. So they want to throw the baby out with the bath water. So throw. There's also good and bad. But I love how you highlight the point that our modern inventions, these chemicals that these microbes might not be exposed to in the past, could be leading to detrimental effects holistically on the body.

Absolutely. I just want to come back to a positive effect and with potentially huge implications. And that's. It's the microplastics. Certain microbes can break down microplastics in CO2 and water. So companies. There's one particularly, actually, I'm an advisor to this company called Melius. They're working on microbial strains, on beneficial microbial strains that are specializing in breaking down the microplastic that you would ingest into water and CO2. So totally harmless substances. And I think, you know, when you look around, I mean, there's. There's no good chance in the next, I don't know, 20 years that we get rid of our plastics. You know, we're ready. People already can detect microplastics in the heart and the testicles and, and we have no idea what effects those have. You know, so since we're unlikely to change our behavior and using plastics for everything, including the vegetables we buy in the market, which think are healthy, something like this, a breakthrough, that of a bioengineered microbe that can actually convert, you know, this microplastic into totally harmless substances would be phenomenal. You know, and my prediction would be, I'm somewhat biased because I'm affiliated with this company, but my prediction would be that these are likely scenarios to happen, that you modify the genetic code of certain microbes to add functions that the microbes didn't learn in the 4 billion years when they were around, but that we have to add today because we're dealing with all kinds of new chemicals and perturbations of that system.

That's incredible. I mean, it's huge news over the last couple of years on the accumulation of bioplastics into the body through the environment. And you're absolutely right, microplastics are not going away anytime soon. So it's so exciting to hear these sort of developments in synthetic biology to actually mitigate some of these risks of microplastics. So just one follow up question, if you could share, and I understand it could be confidential, but broadly speaking, are we talking about lactobacilli type bacteria, bifidobacteria, breaking down these plastics?

Yeah. So these will be microbes from, that normally grow in our intestine, but changing something in their genetic code that they now are able to, when they encounter a microplastic, that they actually metabolize it. So that whole technology of synthetic biology.

Or.

Genetic engineering of microbes, it has a negative bite taste for a lot of people. They think, oh my God, we don't need, you know, genetically modified foods and, and, and, and, and microbes. But I, I think there's an opportunity to use an amazing system that we have living inside of us for certain once we know it's safe. You know, I mean, obviously you always need to make, make, make sure that whatever you change in this genetic code does not have unintended consequences like releasing rabbits in Australia, you know, so it's something like that.

Absolutely. Or foxes or feral cats and goats and all sorts of donkeys, all sorts of weed and wonderful things. I also have mixed thoughts on synthetic biology, but it's use cases like this particular example that excites me because we know we have this problem that's very difficult to solve. And we're seeing more and more research coming out on the accumulation of these plastics in the body. So I'm very open to exploring solutions to these particular issues. And one thing I'd like to come back on is when you mentioned the difference between hydroponic foods and organically grown vegetables in the soil, could you speak a little bit about the actual amount of bacteria that's actually coming via the consumption of foods that are grown in the soil?

You mean the bacteria that we ingest from, from the food?

Yes, the load.

You know, that's not the main thing that, that I've been thinking about really. You know, just this may be, this may be more important. I mean the way that, you know, there's a lot of root products that in, for example, in traditional medicinal practices, you know, ginger and turmeric, I mean, there's a lot of roots. I don't know how much of these bacteria that live in the, what's called a rhizosome, basically these rootlets that come out. How many bacteria are left after drying and processing and turning these roots into powder? There's certainly, you know, and there have been studies like on oranges that are organically grown, how many bacteria are coating the peel of the oranges? And that's very true about most foods. I do not know. I couldn't give you an informed answer really what importance that has. I think it's more important the role of the microbes in the development of these plant based products. As we told earlier, you know, interacting with the roots or with the leaves. If you take that away, then you know, one whole class of molecule of beneficial molecules like the polyphenols and I should say polyphenols, that's a very interesting group of molecules. It means many phenols. So phenol is a ring, is a chemical ring. So polyphenols and many of those link together to making up a very big molecule that cannot be absorbed in our first half of the small intestine because we don't have the enzymes to break it down. And it's too big to be absorbed passively. So we need the microbes to break those down into smaller molecules in the end of the small intestine and in the first part, the colon. And so those, those are the molecules that are like the, you know, that, that reflect the history of the plant, how, how did it evolve, how, you know, how was it grown and what encounters did it have while it wasn't in the soil and if that's taken away. And you know, I mean, we never did that study, but we had planned a study where we compare the polyphenol content of plants grown in the laboratory, you know, with regenerative organic soil. And so regenerative organic is another for people who don't know this. It's a movement right now, luckily a rapidly growing movement. We don't just avoid chemicals, but you actually give back to the soil. You don't just take out, you know, all the nutrients and deplete the soil, but you give back by the various crop rotation and various, you know, techniques that have been shown to be practical and also are cost effective. It's not that regenerative organic agriculture is this, this, this hippie way of making things that would never make money. It's. There are people, there's a person, Joel Saladin, a farmer in Virginia, who has clearly shown that this can be, you know, mass can, that food can be mass produced with that technology and with making sufficient profits. So that that rationale that you can't make a business out of this is totally wrong. You know, it's a myth promoted by the, by the agricultural lobby, but industrial agricultural lobby.

I hear you. So if I could summarize going back to the plant, the plant story. So it's not so much about the microbes that we're ingesting, it's more about the, the conversion of these chemicals via the soil organisms that are then having a flow on effect onto how these chemicals interact or these microbes particularly interact in the body. So there's this whole pathway that's been taken out by excluding the soil microbes, potentially by damaging, using chemicals and things like that, or using hydroponics where you're just taking the soil completely out. And then you moved on to talking about regenerative agriculture, which I'm a huge proponent and fan of. Hugely important in terms of the quality of meat that's produced and also the environmental benefits, for sure. So do you have any comments? Because I'm getting a lot of questions these days about a particular chemical that's used, that's been introduced into the agricultural world, especially when it comes to, to cattle raising. It's called bova. Have you ever come across that?

No, I've not. I'm not hear from you about it.

So it's, it's basically consumers that are asking us about the addition of bova into the animal's life cycle, I assume via some sort of supplement that suppresses methane production. So there's a huge public backlash against Bova at the moment. So you might not be aware of that, but that's certainly happening. But to your point, my personal take in, I, I don't know what the flow and effect is by introducing this chemical into the meat. It's, it's an unknown to me what the downstream effects are on the microbiome because a lot of the methane is I'm assuming going to be produced by the microbes in the cow's gut.

Yeah, the fermentation, I mean the whole digestive process in cows, the fermentation is something that's totally dependent on microbial populations and that has been influenced really by the way that in meat production. So they use to use corn instead of grass, which is harmful for the cow's digestive system and causes inflammation. That's sort of a good example. Completely ignoring really the net, the role that has evolved over thousands of years in the ancestors of cows and you know, bisons and other wild animals that yeah, we've sort of, you know, much in this field of nutrition and food production has ignored for a long time the key role that microbes have in it, you know, in many different ways. And when new things come up, I mean another example, you know, like where microbes also might potentially have an important role. So most of our farm animals that are raised in, you know, really horrible conditions in many parts of the world, when you think about the mass production. So a large percentage of these animals have inflammation of their intestine, of their large intestine. So even though they're considered healthy, if you take biopsies or if you look at inflammatory mediators, they have this widespread inflammation due to several factors to the chronic stress, but also the way they're being fed. And the microbes certainly play an important role in that as well because they normally would have, could have an anti inflammatory effect through production of butyrate on these processes. And I should come back to this, you know, I mean I, I definitely don't want to be a salesperson for genetically engineered microbes. But another way that this is being addressed right now is by again modifying microbes that, or probiotics that are normally don't like to be in an environment of inflammation to alter these microbes that they actually thrive in an inflammatory environment and produce their anti inflammatory substances, butyrate and you know, that which is sort of like the endogenous aspirin of the, you know, of the body or the microbiome. So those, those probiotics, this genetically engineered probiotics also have shown early beneficial Effects in animal models, you know, pretty dramatic. So it could well be that we're going to harness, harness in the next, you know, version 2.0 or 3.0 of the probiotics. A lot of possible real health benefits. I mean today, probiotics, I'm, I think, you know, for a lot of people, they like them, they feel better, you know, but, but they don't have the traumatic effects that we might get with the second generation or the third generation that I mentioned, you know, where we can treat not just diseases of, of humans, but I mean, when you think of what, what a, what a crazy situation that we did that we eat meat from animals that are, that are sick basically, you know, because the way they raised them, what they fit and the antibiotics that they get, it's just certainly another reason for people that don't eat meat, red meat, not to eat it. You know, because. Yeah, having learned about this, this ubiquitous role of gut inflammation in ag in modern agriculture. So we talked about the chemical agriculture which is so damaging to the plants. Now we're talking about, you know, raising animals where it's equally detrimental. You know, and the sad thing is all of this is being supported by subsidies from the government. I mean the US Government spends hundreds of millions, maybe billions in, in subsidies on, on, on many of these unhealthy farm practices. So I think raising awareness of this for, by the consumer, it has to start with the consumer. The consumer has to ask the question, you know, where does this meat come from? And are these healthy animals, are they grass fed and free roaming? Or are they, you know, so this, I, I think the, the, the consumer is being tasked with being a lot more inquisitive, both being aware and inquisitive when they buy and how and where they buy their food.

Completely agree. So to summary, to summarize the, that sort of topic point that we discussed. So the course of action for the consumer is to ask questions, be more inquisitive, more curious about what they're putting in their bodies. But then perhaps choosing foods like pasture raised, regenerative agriculture, organic grass fed, these type of things in that meat world and then in the vegetable world as chemical free as possible, organic, actually grown in the ground with soil. So you get that conversion process of the polyphenols. And one thing that recently popped up in a study that I read maybe like two days ago, there was a study done on particular coffee polyphenols and how those polyphenols actually promote a growth of a certain organism in the gut. That's really unknown. All we know that it's a butyrate producer, but it does, it does boost that level of fat organism in coffee drinkers. And it was quite a broad study. There was big cohort. So any insights onto polyphenols like coffee or could be things like pomegranate. Is there any, any information you can share around polyphenols and the potential benefits?

Yeah, so I'm, I'm a huge fan of polyphenols, I have to say, you know, right now, and I mean I've kind of known this really even before the microbiome science exploded that plant based food is healthy because of the fiber content. You know, people have known this for quite some time and initially as a gastroenterologist you saw this because of its benefit on bowel function, on constipation. But that's just a small part of it really. Fiber is another one of those molecules that do require microbes to break it down to complex carbohydrates to break it down into smaller molecules that are then being absorbed in the end of the small intestine or in the colon. For our ancestors this was a bigger problem because like before we had fire and cooking and processing ways of, of plant based foods, we were totally dependent on these microbes. So now if you, if you cook or fry something, you already break down a lot of these complex molecules. But, but there's still a need for, you know, for the microbial metabolism with, with the polyphenols does. So there's lots of, there's, there's a big portion of science in the, in the preclinical field in cell systems where they, these polyphenols act as antioxidants. You know, and that's generally what people think about when they talk about polyphenols or their antioxidants. Well, they're antioxidants protecting against free radicals which are damaging to the cell. But that effect is only when you have this intact large molecule acting on another cell. If you ingest these polyphenols, they can't have that same effect because they can't be absorbed intact. The first broken one and then are being absorbed. They have a beneficial effect on one the microbes. They nurture the microbes, they increase the diversity and in addition, the microbes break it down into molecules that are beneficial for us. So eating polyphenols has multiple benefits from the microbial ecosystem gut health to, you know, brain health, protection, like protection against early cognitive decline, protection against cardiovascular disease, a couple of really large scale well, controlled trials, which is rare in the, in the food area era food, but definitely they do exist for some of these polyphenols. So one is called flavanol, which is contained also in cacao beans and many berries. So that's. Yeah. So there's a lot of evidence, unfortunately for the polyphenol field, it was very popular. I don't know, it was 10 years ago or 15 years ago where it was sort of this explosion of interest in antioxidants. And then the FDA put up a website where you can look at the antioxidant potential of each polyphenol and industry jumped on it, the supplement industry jumped on it. But then it was shown in experiments if you ate these polyphenols either as extracts or in the form of the whole fruit, that very little of that parent compound showed up in the blood. And the FDA ultimately took down their website and this whole field got sort of tainted. People said this was really not a clinically relevant effect that we saw in these cell cultures. It's gradually coming back. Now that we know why these parent molecules were not detectable in the blood because they're not absorbed intact. I think there's a growing interest and I personally think it's one of the most interesting parts of a largely plant based diet, essentially adding to the health benefits of the fiber and, and fermented foods. So like you have three components of, you know, that you could say make up most of the health benefit of a largely plant based diet. Fiber, polyphenols and, and, and fermented foods.

That's incredible. That's, that's like the perfect jumping off spot to go into your wheelhouse, which is using diet and, and food and things like that to really impact mental health, which is really the star of the show. But I just want to come back to that, that polyphenol and why those molecules didn't show up in the blood. So is that because it didn't go, it had to go into the gut to be converted by the microbes? Is that why it didn't show up?

Yeah, it couldn't be absorbed in the form that it was picking up or you know, was eaten because it was too large. And so first they had to travel down in the, called the ileum, the last part of the small intestine where they already have a high concentration of microbes. It's just not just the large intestine, it's also, you know, the end of the small intestine. It had to travel down there and then Again, it was not absorbed intact, but broken down. So the pieces into much smaller phenol molecules those could be absorbed and they also fade at the same, as I said earlier, at the same time these smaller molecules fit the microbes to thrive. I mean, I always say identifying a healthy diet is always a diet that's good for our microbes, which is the fiber and the polyphenols and the fermented foods. If you just focus on that, you can automatically get the, the maximum health benefits of your diet.

Absolutely agree. And one of these important factors is something called gut microbiome diversity and how consuming all these different types of plant fibers, polyphenols and molecules that are similar foster microbiome diversity. So are you able to speak to how important microbiome diversity is for our mental well being? And then are there any specific bacterial strains that you believe are non negotiable for optimal brain health?

There's a lot of speculation that you have to use there. So there's, there's studies, people have looked at this, you know, how, how diversity, which means how many different types of microbes are there, and richness, which means how much of each of those strains are there. So it's not just you could have diversity of having one strain of a thousand strains in your gut. This would not give you the healthy microbiome. You need the richness and number of these. So just like, I mean ecosystems, the microbiome is an ecosystem. It's just like if you think about a city is an ecosystem, if you have a large diversity of professions, of people from different parts of the world, not just one person. So if you get one person from one African country, it's not going to add to the diversity of the health of your city if you have different, you know, significant numbers of people from different parts of the world. I think there's no question, I mean London is a good example, Los Angeles is a good example. I mean all the big metropolis, you know, show that phenomenon that it's that diversity and richness if that translates directly into brain health. So people have looked at these studies, they were not as clear cut as you would hope. You know, they, they should be. So I mean, decreased diversity or today we sort of, when you want to define what are the criteria for a healthy microbiome, it, it sort of goes back to ecosystem health, health in general. You know, any ecosystem that you take being in the ocean, being in the forest, being in cities, it sort of has the same basic underlying principles. It's, it's what we talked about multiple players and sufficient numbers that are all interconnected. So this interconnectedness concept is a key, you know, to that. And so when we do these studies today and we sort of correlate, you know, like you take normal populations in the US or in the uk, I mean they're not really, they're not really the normal that you would find if you go to the hunter gatherer remnants in the Amazon or on the Orinoco river, you know, who have these ancient microbiomes which are much more diverse, much richer. So we don't have that anymore. So our healthy control groups in, in our studies already depleted of many of these ancient microbes. And so some people have warned, you know, there's a book out, Missing Microbes from highly recommendable book by Martin Blazer where he sort of describes this, this process, how gradually we're losing more and more of these ancient microbes, just losing species everywhere in all our ecosystems. But that's happening internally as well. So to compare to take a population that doesn't have a disease yet, it doesn't mean that they have the healthiest microbiome. So I would say in general we know it more from the other side. So if we, if, if we improve the diet, which often generally means improving, going more towards a, you know, 75 plant based diet like the Mediterranean or the, the Okinawan diet or other sort of diets around the world have, they all have the same principle if, if you make interventions or do epidemiological studies. There's many of these epidemiological studies that, that's in general associated, not causative but associated with a, with healthier brain function both in terms of, you know, emotional disorders. But also I think a big focus now is on this early cognitive decline, you know, brain inflammation, low grade brain inflammation and degeneration. And I think there is pretty good evidence to link this to the microbiome in many ways. So just looking at the diversity and richness doesn't give you the same clear cut effects as is now suggested by these epidemiological association, large scale association studies. You know, there's studies like the Harvard Public Health School is sort of the leader in this, putting out these, to this, the Harvard Nurse study, you know, tens of thousands of male and female nurses being followed over a long period of time. So those studies show that health benefit of a healthy diet. These studies have not included from the beginning the microbiome diversity. I would love to see that. Is there a close association as we suspect there should be?

Are there any types of bacteria. It could be as broad as you want or as specific as you want. You can go down to the psychobiotic realm or you could talk broadly about the types of bacteria that are very important for mental health.

Yeah, I would say the simplest way, simplest answer to this is to say right now, when we talk about good bacteria or beneficial bacteria in general, they are effective butyrate producers. You know, so taking complex carbohydrate or fiber molecules and breaking them down into these smaller anti inflammatory, I mean they, they not only have anti inflammatory effects but have many other benefits. Nurturing effects on the, the gut lining. And I would say at the brain level the anti inflammatory component is probably the most important one. So you could almost say even if you're on an unhealthy diet, if you eat enough food components that generate butyrate that would compensate for the negative effects of, let's say, you know. Yeah, a lot of red meat consumption or high fat consumption. You know, it's, it's almost a yin and yang, you know, it's the balance if, if you produce enough for these, these anti inflammatory molecules and there are certain bacteria, You know, that are just like there are the top butyrate producers that we know and the number of these bacteria goes up if you go on a plant based diet. There's also another one got a lot of attention, Akamansia, that's a microbe that plays a big role in the, in the mucus, shouldn't say mucus production, in the mucus regulation. So the mucus in intestine is a key component of the intestinal permeability. So a lack of this mucus layer is associated with an increased permeability or. Linguists, the leaky gut, you know, so, so ansia is an interesting organism because can feed on the mucus which are like in the wider sense sugar molecules. That does. So if, if you don't eat a high fiber diet and, and your gut microbes don't get enough fiber. So Akkermansio has a mechanism to survive while just switching to mucus consumption. And it's not just a consumption of the mucus but that triggers also through this organism an increased production of new mucus. So essentially what Akamanta does, it changes the turnover which appears to be a health promoting effect. So somewhat different from, you know, from the, from the butyrate production. And then you could say there's some bad microbes, you know, that play a role in, in the conversion of tryptophan to molecules. So tryptophan is the precursor of serotonin, which we all, you know, so we like that hormone, it's been called a happy hormone, which is kind of an exaggeration. But, but there's other metabolites that can be generated from this essential amino acid tryptophan. That, that balance between serotonin and another one is metabolites canuronine or indoles that balance. So the canurenine is, is, is, is not a healthy metabolite. If it gets to the brain, it can actually lead to increased excitability of nerve cells and degeneration. So does you know the microbes would play a role in this, in this metabolize in this metabolism of tryptophan also play a role. So there's multiple mechanisms. One is in the generation of beneficial, what we call neuroactive substances that are good for the brain. Another one is akamansia that improves the, the mucus layer and the barrier and in the gut. And and then the third one are just complex carbohydrates which lead to butyrate production. So these are just three examples, you know, of how different population of microbes can, can contribute to gut and brain health.

Amazing. I'm, I'm highly cognizant of your time that I don't want to take too much of your time. So we'll start to wrap up. But I, I'd be, I'd be extremely appreciative if you come back and do around two and you can go deeper into the gut brain axis. But just one final question, then we'll start to end the podcast because I think you mentioned fermented foods and I think it, it's worth exploring that just a little bit. So there's a whole gamut of different fermented foods that people can consume. So examples might be kefir, sauerkraut, kimchi, natto, miso soup, all these type of beneficial foods that we can consume that can contain other microbes like probiotic type organisms or beneficial bacteria, beneficial metabolites, postbiotics, prebiotics. So how, how do these fermented foods exert a positive impact on mental health?

Yeah, so there's a lot of again pre clinical studies, you know, mouse studies that have shown that, you know, different micro. So in with fermented foods per se. Fermented foods are not probiotics. So for probiotics there has to be a demonstration of science, had to be scientific evidence that they have a health benefit. You, we don't have this for sauerkraut, for example. You know, it's Not a control study. I don't even know how you would control it, you know, but for the, for these, for many of the molecules, the microbes that are characteristic for fermented foods like lactobacilli and bifido, which are two of the most common ones, there's evidence from these in vitro studies that they have effects on, beneficial effects on the, the permeability of the gut and inflammation. And those are very difficult to reproduce these findings in human studies, in intact human studies, and there's few of them, But. So I sort of lost my train of thought right now where I want to go with this. There was a recent study, it was recently, a couple of years ago that was kind of interesting and was, I think, against what the investigators had suspected that people that consumed a diet rich in different fermented foods had a better initial, a greater initial benefit for, you know, decreasing inflammation molecules in the body and for diversity and the health of the microbiome. Then the people that consumed a diet rich in various fiber containing foods. And the most interesting part about this study was that they found it wasn't the organisms that were contained in the probiotic in these fermented foods, it was other organisms that were then all of a sudden detected in the gut. And I don't think it has been resolved by the investigators where these other molecules came from. Were they already present in the gut in sub detectable levels or were they introduced with wherever this fermented food came from, you know, from contaminants, so to speak, of the fermented foods. But I think that study has kind of really generated a renewed interest in the benefits of fermented foods. And I personally think about it, this is what I recommend to my patients. Instead of now going for the latest probiotic pill or capsule, just introduce multiple fermented foods into your diet, depending on your preference and food tolerance. And I think a lot of people are doing this in different parts in the U.S. but it's not, you know, there's, there's still the perception you have to get your probiotic pill in order to get, you know, to get the benefits of fermented foods. Ultimately how this will be decided, I always feel with healthy foods it's better if you eat a diet that is rich in, in these ingredients than eating the pills. But then there's, there's a lot of the big parts of the population that are, have insufficient levels of, for example, the polyphenol intake or fermented food intake, and they may live in food deserts or they may not be able to afford, you know, the kind of foods that, that other people living in more privileged areas have. So for those individuals, I think the. The supplementation was with pills that are enriched in these beneficial molecules is probably the best way to go. So it's not one size fits all. I think you have to sort of determine who are the customers, do they have access to this healthy food and to five different fermented foods. So many ethnic groups have it when they maintain their cultures, even though they may not have these same affluent supermarkets that are, you know, in the posh parts of London or Los Angeles.

So, yeah, what's become hugely popular at the moment in the Zeitgeist is people using popular strains like lactobacillus rotary and making yogurt, like, products out of it. So opening up capsules and then fermenting it in a yogurt maker. Have you come across that before?

I've not come across it. It must be something that in the UK is you guys.

There's a little bit of a craze going on. I think it was popularized by Dr. William Davis, another guest of our podcast. But what he advocates is to use these particular strains. And you're absolutely right. I mean, there's no really proven probiotic strains in fermented foods. The only outlier would be something like a yogurt, where they might make yogurts with the probiotic strains. But then what Dr. William Davis is talking about is you open up the capsule, or they even sell it as powders, and then you put that in the yogurt maker so you boost up these strains of these probiotic organisms. So it's really interesting, fascinating. It's a bit of a craze at the moment, so I'm sure people will check that out. Previous episode with Dr. William Davis to learn more. But Dr. Emra Mayer, thank you so much for your time. I could speak to you for another five, six hours easily. But I want to get you started with the rest of your day. I know you're extremely busy and you have lots of stuff going on, but if people want to reach out to you, they've loved this podcast. They want to find your books, they want to find you online. How do people find you?

I think the simplest way is just to go to my website, amaranmayer.com and sign up for our newsletter. It's a collection of all the podcasts of all the posts that were part of our newsletter. We always deposit them on the website as well. Yeah, I would say if you if you don't want to, if you haven't read, you know, any of my books. I mean this is definitely the simplest way to, to go to and, and they're making big improvements on, on, on the website and the ease to, to access this information. So I should mention one thing. I, I wish, you know, because I'm at this scientific meeting here. So it's, it's American Culture College of Neuropharmacology and it's, it's kind of ironic that we have this, this conversation right in the middle of it and, and there was a part of this meeting and one and a half hour workshop on, on, on psychedelics. There's actually one right after this conversation that we have. This has become a hot topic in, in, in, in, in psychiatry and in medicine as well. And, and there was a talk, so talking about the role of the microbes were the, the microbes, you know, have receptors on them that these serotonin receptors that these psychedelics like psilocybin stimulate in the brain. But there's different phases of, of the psychedelic action. There's the initial visual, you know, experience and then there's a prolonged period where, you know, your verbal communication increases and then there's month long effects as well. And so there was a presenter and I've thought about this idea for a long time that the delayed effects, you know, may easily have to do with what these components of the mushroom do to the microbes. I would, I would bet my money on it right now that I would say this is going to be another area that will. Because I mean these long term effects seem to be beneficial. You know, people talk about neuroplastic effects. It changes the brain circuits and that the studies going on in refractory depression and in ptsd and it may well be, if you had this conversation in five years from now, this could be one of the main topics that we're talking about. I just want to throw this in because I'm amazing. Five minutes and returning to that.

That's incredible. You've dropped so many amazing nuggets right through this episode. Things that I've never heard before. And this is about bringing this cutting edge research straight from your conference directly to the general public to absorb and take on. So thank you so much and I'd love to end on this note, slightly different to normal, but if there's one thing you could do for your gut brain connection today, what would that be?

One thing? I, I think if you had to limit it to one thing, I would say focus on a healthy diet which in its components percentages is like the Mediterranean or similar diets which is grown organically ideally, you know, in the regenerative organic fashion. I, I think that would be the number one. You know, I, I think of the evidence that we have today that would be the one. There's many experimental things that going on and but I, I think focusing on on the diet card would be important.

Thank you so much. Amazing Dr. Emran Mayer.

Thanks Krivin. Wonderful conversation. Really enjoyed it.

Thank you.

We hope you enjoyed this episode of the Gut Health Gurus podcast with Dr. Emran Meyer. If you found this podcast valuable, please leave us a kind review and five stars on Apple, Spotify or your favorite podcasting app. If you want to connect with our host, Kriben Govenda, please follow him on Instagram, Facebook and TikTok. Gut HealthGurus. Also check out our Gut Health Gurus Facebook group. With more than 19,000 members ready to help you on your journey to amazing gut health. This episode is sponsored by Nourish Me Organics. Head to www.nourishmeorganics and use the code Happy Gut for 10% off until next time.