Episode 9: The Mind-Gut Connection with Dr. Emeran Mayer


Dr.  Wendy Slusser  00:03

Today I chat with Dr. Emerson Mayer, director of the G. Oppenheimer Center for Neurobiology of Stress and Resilience, and UCLA Distinguished Professor of Medicine, about the bi-directional communication between our mind, brain, and gut. We’ll answer the question of what the mind-gut connection really is, and how it may be affected during these unique times, and how we can improve our diet to foster a healthier microbiome.  Thank you for joining us today during this pandemic. A lot of us are facing changes in our eating habits, and sometimes drastic changes as our usual sources of food are cut off or limited. I’d like to focus today’s conversation on your area of expertise, the mind-gut connection, and how it relates to the current time. So to start off with, what is the mind-gut connection?

Dr. Emeran Mayer  00:59

First of all, Wendy, thanks for having me on the program. And to give you a brief answer, it’s essentially, first something that everybody has experienced, a relationship between what goes on in our brain, in our mind, and our emotions, and what happens in the gut and what we feel in the gut. This has been known to people for a long time, but has become a scientific discipline much more recently, particularly with these sort of the microbiome science that has made this a lot more exciting to people than it has been before that. So it’s a biological connection. It’s not just in our minds, it’s not just in our gut, it is multiple communication channels that mediates this. And the communication goes both ways. It goes from the mind, the brain, to the gut, and it goes from the gut to the brain.

Dr.  Wendy Slusser  01:48

So I think, to unpack what you just said, the first question I have is, can you define microbiome? Because when you first defined it, for me, it was kind of a wild thought to imagine the quantity and the age of them. And so could you sort of elaborate on that?

Dr. Emeran Mayer  02:06

Yeah, so it’s the numbers have gone, you know, the comparative numbers between human and microbial cells has sort of undergone some evolution, but as up to 100 trillion microbial organisms that inhabit, that live all the way really from the stomach to the end of the large intestine. The highest density by far is in the large intestine, then comes the end of the small intestine, and very few in the stomach. So in terms of what we know today, many from studies focusing on analyses of stool samples, we get a mix of all of these. So we can’t really tell exactly, you know, what we measure in a fecal sample, if this comes from which part of the GI tract, which is important, but we just don’t have the answer. Now, there’s about 100 trillion of these microorganisms. There’s just different types, there’s the microbes, the RK, the fungi. The area we know most about are the bacteria. So the number is about the same, rough plus/minus, it’s about the same as our human cells. So we are half-human, half-microbial, really, and it’s been called a holobiont, you know, because we live in such close synchrony with these organisms. But what’s even more informative is that we have about 20,000 human genes. And we have, you know, millions of microbial genes. So the capacity for these microbes to produce molecules that influence our human physiology, the gut physiology, and also the brain and this brain-gut communication is enormous. We just, at the moment, are scratching on the surface of understanding this. It’s really a rapidly emerging field with rapidly developed technology. But so we can say, because it’s also in evolution it’s been with us, with animals from the first primitive animals millions of years ago, to today, and has really become a blueprint for most animals, from the bees to mice to, you know, horses, humans. We all have a microbiome. There’s only a few species that don’t have that. So it seems to be a very important evolutionary design, in human life and in animal life in general. I mean, the connection to the brain is even more intriguing because many of these molecules that the microbes can produce are what we call neuroactive molecules. That means where they have homologues in the nervous system, means molecules that look very similar can act on the same receptors, and that can interact with our nervous system. There’s these neuroactive molecules and there’s also molecules like short-chain fatty acids that they produce from fiber that we eat, that have a positive influence on gut inflammation, for example. So really two different types of signaling molecules: some that act directly on our nervous system and others that can influence the nervous system indirectly through regulating inflammation in the gut, which then can spread throughout the organism all the way into the brain.

Dr.  Wendy Slusser  05:27

So these neuroactive homologues that they are producing, they get into our system? Is that what you’re saying?

Dr. Emeran Mayer  05:36

Yes, and we don’t know to what degree these different pathways are important. So one very important communication channel is the vagus nerve. You know, the vagus nerve innervates, amongst all the other nerves in the gut, particularly, plays a major role in the signaling from the gut to the brain. These nerve endings of the vagus in the gut have receptors that respond to molecules that are produced by the microbes. So that’s one communication pathway. There’s another one, the vagus nerve innervates cells in the gut that produce hormones, and serotonin, and these cells respond to signals from the microbes. So there’s an indirect step in between the microbes signaling to these hormonal cells, which then act on the vagus and then go to the brain. And then there’s some of these neuroactive molecules – people have, you know, speculated this – that actually are being absorbed, and get into the bloodstream and reach the brain directly, which, you know, if they can cross the blood-brain barrier, or if they reach regions that are outside of the blood-brain barrier, like the hypothalamus, can influence brain function and brain activity.

Dr.  Wendy Slusser  06:50

So you mentioned the serotonin, I understand, you’ve educated me on this, it’s predominantly produced in the gut. Is that right?

Dr. Emeran Mayer  06:58

Yeah, even though, you know, it plays such an important role and we know so much about serotonin, what it does to the brain, from mood, pain sensitivity, sleep, appetite, well-being. There’s very little of the serotonin that’s in the brain, in these nerve cells in the brain, just about probably less than 5% of our total body’s serotonin. Whereas most of it is stored in these, they’re called warehouses in the gut, these so-called enterochromaffin cells that, you know, produce serotonin, store it, and release it. And, probably too long a story for this conversation, but a lot of work that has come out of UCLA, particularly Elaine Chao, investigator of some of these pivotal studies, is a close interaction between the microbes in the gut and these enterochromaffin cells. So the microbes are responsible for the regulation of the synthesis of serotonin in our cells. So the microbes send signals to the cells to stimulate serotonin, to release serotonin. The serotonin cells, in turn, talk back to the microbes. So they release the serotonin not only inside of our body, but they talk back to the microbes. And to make that story more intriguing, the microbes have molecules that are similar to the serotonin transporter that we have in our brain and in our own cells, which are the target of antidepressants, of serotonin reuptake inhibitors. So the serotonin-microbe-brain interaction is a good example how intricate this relationship is between them. And I forgot to mention, obviously, the microbes and their activity to stimulate serotonin production is closely related to the amount of tryptophan that we ingest. So a close link between our diet, to microbial activity, to serotonin synthesis, serotonin influencing brain functions through the vagus nerve, and talking back to the microbes, telling them, well, we don’t really know what our serotonin tells the microbes, so that’s still an unresolved question.

Dr.  Wendy Slusser  09:14

I want to get back to the tryptophan, but before I do that, I think that what you’re describing to me really implies,, or suggests that what we put in our own mouths that gets down into the, what would be ultimately our large intestine which is where most of these microbes live, that even the small intestine is critical, or might be critical, for influencing these microbes to do their job. Am I correct in thinking that way?

Dr. Emeran Mayer  09:44

Yeah, absolutely. And to me, it’s sort of really been an eye-opener to realize. So I’m not trained in nutrition, but I’ve gotten fascinated with this topic because clearly, it has such an important influence of this key function of our brain-gut-microbiome axis, that not taking into account, for example, in psychiatric disease or in our well-being, is leaving half of the story out, you know. And I think this continues that we really don’t, I would say 99% of our medical students, have not heard about that story.

Dr.  Wendy Slusser  10:19

Yeah, we’re working on that right, you and I. It’s an important piece. Well, so, let’s talk about tryptophan, which you know, all of us know about tryptophan during Thanksgiving time, right? God, it puts us to sleep. Tell me, is when you’re saying tryptophan influences microbes, is it in a positive way? Or in the microbiome? Or is it a negative way? Or how, or is it more complicated than that?

Dr. Emeran Mayer  10:48

It’s more complicated, like most things in the gut. So you know, tryptophan is just really the precursor that microbes then metabolize in multiple different molecules. And to stand out, you know, one is the serotonin that microbes themselves don’t produce. They can’t produce it so they use our enterochromaffin cells, to stimulate our cells to produce it, and then they take it up from the cells. But there’s also another one, another metabolite, called kynurenine. Nobody can remember that name, but it’s a pretty important molecule, probably at least as important as serotonin, because it can cross the blood-brain barrier. And it has been shown to have inflammatory and neurodegenerative effects on the central nervous system. So the ratio between kynurenine and serotonin is regulated, in part by microbes, you know, when we talk about diseases that are involved with what’s called neuroinflammation, so immune activation in the brain, kynurenine often comes up as a key signaling molecule that plays a role in this. But there’s many others, there’s the indoles, each of which has specific functions. Obviously it’s important to realize that only some of them can cross the blood-brain barrier and affect brain function. Others act on the gut, on the vagus nerve, on other cells in the gut. So the simple story is, there’s two of these metabolites: serotonin and kynurenine, both of which played very important roles, sort of in opposite directions, really. And what you say earlier about the tryptophan: so like all dietary items, or most dietary items, I would say the majority is absorbed in the small intestine. So we have very elaborate, specialized mechanisms, transporters that can take up these molecules. The exceptions are very large molecules, or molecules for which we don’t have enzymes to break them down. So the very large ones would be the polyphenols, people often mislabel as antioxidants, because there’s just one small function that they have. So these are too large to be absorbed in a small intestine, they all go down to the microbes. The microbes break them down into smaller metabolites, which then are being absorbed, and they’re the ones that exert their beneficial effects, incompletely understood, really, on the brain. The other one is the dietary fiber, that, particularly if it’s not processed,or cooked, we don’t have the enzymes to break it down so it goes down to the microbes. It’s actually the main food supply, the main nutrition for the microbes. So I always say it’s a very easy answer to the question, you know, what can you do for your gut health? So you got microbial health. Well, it’s eating a lot of plants with fiber, because that’s what they thrive on and that’s where they produce their one class of molecules, I mentioned earlier, the short chain fatty acids that have beneficial effects really on pretty much all the cells in the gut, you know, the epithelium, the lining, the anti-inflammatory, they stimulate growth of gut cells. They act on on vagal afferent terminals signal to the brain. Yeah, so coming back to the tryptophan, like many things, we know many nutritional things. Classical nutrition, the field has learned a lot about the stuff that we can absorb in the small intestine. But it’s really just beginning to understand the full potential of what cannot be absorbed in the small intestine, but that goes down to the microbes. And I do want to say, in my opinion, it’s not just the colon, even though there’s most of these microbes. There’s a lot of them in the end of these small intestine in the ileum. And even in the end of the jejunum. So many of these beneficial processes may well happen in a small intestine, but we don’t really know that for sure.

Dr.  Wendy Slusser  14:51

Just so we can summarize just what we’ve talked about so we can move on, to people who might be eating for comfort, that might not necessarily at this time be the kinds of foods we want to feed our microbiome with. Or maybe there’s a balance that we can come around to. But what you’re describing is eating a diet full of fiber that also has polyphenols and foods like that, or eat the rainbow of vegetables and fruits, that kind of diet, which we all have heard about. But if you go down to the granular, it’s really about sort of the diversity of the fruits and vegetables that are as as important as one fruit itself, right? You have to have a diversity because there’s differences in what they can bring to you. It’s that, kind of?

Dr. Emeran Mayer  15:47

That’s a very important point. So, you know, Rob Knight with the American Gut Project, they have found from their survey of thousands of fecal microbial samples from volunteers that have sent them in, that it’s really the variety of plant products that determines, that has an influence on the diversity and the richness of the gut microbes. And, you know, Rob, obviously this is his example, you can be a vegetarian and just eat pizzas. That will not give you an increased diversity of your gut microbiome. The more diversity that you can add to the vegetables and fruits that you eat, the better. And it’s makes a lot of sense, because there’s hundreds of different fiber molecules, and there’s thousands of different polyphenols. Each of these plant components requires a different set of microbes, different strains of microbes, to process them adequately. So by feeding this kind of a diet, you force the system to diversify. And so that’s really, you know, one of the key concepts. Even though blueberries and olives may have the highest concentration of beneficial polyphenols, there’s thousands of other molecules, polyphenols, in much smaller quantities, in all fruits. But talking about the gut microbiome, so there’s three things, I mean, there’s the plant-based oils and fats, there’s the fiber, and there’s the polyphenols. I would say that’s what plants can contribute. And if you satisfy that need for these, you will automatically get enough vitamins and trace minerals in your diet anyway. So it’s not that you have to monitor each of these, you know, health-promoting components of plant-based food. So it’s actually, in some ways, it’s fairly easy. The science is pretty hard; the practice is pretty easy.

Dr.  Wendy Slusser  17:44

Thank heavens for all of us non-scientists. I have to say, you’re also, besides being incredible scientist, you’re an incredible author. And one of your blogs that you wrote recently regarding how the gut microbiome plays a role in the individual response to the COVID-19 virus, I love this description that you wrote about the world of the microbiome, so to speak. And you say, “Far from being a peaceful world of coexistence, there’s a constant struggle between these microorganisms, using antibiotic molecules suppresses each other, and to preserve ecological niches. So viruses living in our gut prey on the bacteria and kill approximately 10% of the microbial population every day and the gut microbes fight back with a vast battery of antibiotic-like molecules.” It just sounds so hectic down there. I never knew there were things like that happening on a regular basis.

Dr. Emeran Mayer  18:48

Well, it’s just, you know, a miniaturized ecosystem. So if you look around in any ecosystem, you know, you look at Yellowstone, I mean, there’s a lot of non-harmonious things going on, you know. Species are being eaten, you know, the bears prey on some animals. The wolves, sort of one of the keystone species ,takes care on the very top of the system. So something very similar, but in a miniaturized form, you know, goes on within the gut. And the interesting thing about these antimicrobial substances that they produce, I mean, obviously, they can talk to each other, these microbes. That’s why they have these enormous number of genes and molecules that they can produce to communicate with each other. What this communication entails, we don’t really know but we do know that some of these antimicrobial substances they produce limit the growth of other species. So this elaborate system that’s pretty much stable throughout our life is not just something, it’s not static, you know. It’s a constantly evolving and, you know, generated system that requires a lot of work from from each of the participants and survival skills. We don’t know as much about the viruses in this game and the fungi. Obviously, you know, viruses and fungi play a huge role in the soil, another ecosystem that has a big microbial component. And we know more about this in the soil. We don’t know as much at this point. Well, we know about pathogenic viruses, you know, that can create havoc within the gut and kill off a large number of bacterial organisms.

Dr.  Wendy Slusser  20:34

Like rotavirus.

Dr. Emeran Mayer  20:35

Yeah, like rotavirus. And but the ones, the commensal viruses, we don’t know as much about, you know. What regulatory role do they play in? Are they ultimately responsible for some of these microbial differences that we see in different disease populations? We don’t have the answer for that yet.

Dr.  Wendy Slusser  20:54

So getting back to what’s going on now with COVID-19 and people, you know, basically sheltering-in-place, many of us have gone to some of our favorite comfort foods that might not necessarily be promoting our gut. And others might be going to comfort foods that do. And also the scarcity of certain foods are present. So what happens if you are not getting as much of a variety of fruits and vegetables and/or also increasing some of the more processed foods, or you know, simple sugar foods?

Dr. Emeran Mayer  21:32

Here, let me start. The simple component of this question has to do with, you know, what we typically considered the Western diet – high in sugars, refined carbohydrates, low in fiber, and high in animal fats. That diet clearly has been, I mean, it’s a large number of studies now, both, you know, epidemiological studies, but now most recently, also, intervention studies, that this diet has a negative effect on gut microbial diversity and relative abundances of health-promoting organisms. And also on the metabolites that they produce. So in this time, where people may not think so much about, you know, do I get my servings of fruits and vegetables every day, but sadly, you know, where a lot of people are struggling with getting enough to eat in general, which is sort of an incredible situation that we’re in. On the one side, the fruits and vegetables are being thrown away by farmers who can’t get them to the restaurants. On the other hand, you know, the consumers, particularly the lower socioeconomic populations, don’t get enough of those healthy foods. So it’s a strain and stress on the gut microbial health. On top of that, so the comfort foods, unfortunately high fat and high sugar foods, provide immediate comfort. So studies on that, they decrease the the acute stress response, you feel better, you release dopamine. So there’s a lot of things that in evolution have evolved to make us crave for these foods.

Dr.  Wendy Slusser  23:16

Cheesecake’s my favorite.

Dr. Emeran Mayer  23:18

Yes, and I should say, normally, you know, small amounts of these foods are not bad for you. But if it becomes a significant part of your diet, then yes, it will. It probably has contributed a lot to these changes, these negative changes we’ve seen in Western populations. So yeah, this will add, you know, this eating these comfort foods will add another, on top of regressing to a typical Western diet, then you add these things, it makes it even worse. So another aspect potentially may play a role. A lot of people you know, spend a lot of time watching Netflix in the evenings and snack during this time, so after dinner. There’s also a lot of recent science that has shown that time-restricted eating, meaning, you know, you don’t eat around-the-clock. You have something in your stomach, but you restrict the eating to six or eight hours, that if you break that time-restricted eating pattern that also has a significant effect on our gut microbes and the way they interact with our, you know, with our gut-based immune system. So there’s a lot of things just from the diet side here that are not good in this current situation.

Dr.  Wendy Slusser  24:35

Yeah, you’re referring a lot to what’s emerging as the whole circadian rhythm of eating.

Dr. Emeran Mayer  24:42


Dr.  Wendy Slusser  24:43

We’ll have to have a whole other podcast on that one because that’s super interesting. We’ve talked a lot about how a diet, maybe this sort of modern high-fat, low-fiber diet has been adopted by the American population in general, or the Western population. I understand now it can impact these microbiomes, make them less diverse or not as healthy, maybe. What does it do to your mood, or your brain?

Dr. Emeran Mayer  25:15

So we know now, you know, from some of these familiar epidemiological studies, that if you compare populations that are on a typical Western diet, and those that are on a largely plant-based diet, that for example, depression prevalence is significantly higher in the Western diet group, also the risk for Alzheimer’s disease, and probably other brain disorders. But it’s been probably best characterized, I would say, for depression. Recently, there has been studies in this field, what’s now called nutritional psychiatry, where people are doing interventions. So they take a group of people with depression and they are randomized to two types of diets, either plant-based diet or plant-enriched diet, and a typical Western diet. And they found that there are beneficial changes in the intervention arm with a Mediterranean-type diet, such as, you know, traditional Mediterranean, there’s also another acronym called the MIND diet, or the DASH diet, which will all share this property of being primarily was 75% plant-based. So there’s now several studies that just recently came out last week, two of them, which really show that this has a effect not just on the symptoms, but also on the relative abundances, in a beneficial way, of microbes and on some of the metabolites.

Dr.  Wendy Slusser  26:46

And I noticed, in your blog, you mentioned two that were really important anti inflammatory herbs: the tumeric and the ginger.

Dr. Emeran Mayer  26:55

Yes. It’s just the beginning. You know, even though I’m trained as a gastroenterologist, I obviously never heard about this until several years ago, when I got involved in this microbiome science. And it is remarkable, you know, these plants, the molecules in them are such large molecules similar to the polyphenols that most of it cannot be absorbed in the small intestine. So they stimulate our taste receptors in our mouth. So that’s why we, you know, we use them as vices. But then what happens after that, a small fraction is being absorbed, but the largest amount goes down – again, my guess is into the end of the small intestine – is being absorbed, transformed by microbes, then absorbed and then exerts its anti-inflammatory effects, which are so strong, you know, that there are studies, even, that they have been beneficial in the treatment of mild inflammatory bowel disease in a randomized study. So it’s not a trivial effect.

Dr.  Wendy Slusser  27:59

Well, they certainly have been used in traditional medicine My question for all of us, who might have been indulging a little bit more than we wanted to in, say, cheesecake, the recovery time, or your ability to maybe pivot towards these more plant-based foods that you’re describing, 75% being your goal, how long would you say the microbiomes would sort of come back to life, so to speak?

Dr. Emeran Mayer  28:28

Yeah, this is a very interesting question. So at some point, people said they will never come back to life fully. So our Western microbial ecosystem is definitely compromised. Many factors start early in life, probably during pregnancy, nutrition of the mother influences that to a certain degree, as well. So many of these microbes have been lost forever. So they’re like the extinct species or strains. And those are, currently with our current means, we don’t really have a way to bring them back. There’s some populations in the world, in Africa, that live sort of a prehistoric lifestyle, they oscillate depending on the seasons in what they eat between our type of compromised microbial composition and abundance. But in their case, they come back, you know, so they somewhere keep a very small number of these organisms that then, with the right diet, you know, come back to life. In our case, some of them have gotten extinct and, you know, some people have warned if this process continues, we’ll lose more and more of these species. And I like to take the more positive approach to that, or optimistic viewpoint, that if you switch, and this has been now shown in several studies, if you switch to such a diet, that they will come back. Even in these trials that lasted eight weeks, even in that time period, they came back. And these weren’t even diets that I would push, you know, that I would recommend to maximize the diversity of the plant-based foods that you eat. So these are just the regular Mediterranean diet in this study. So the short answer is, we won’t get back to where we were 100,000 years ago. We may not even want to get back there. But we can certainly improve the situation significantly with health benefits, with these dietary interventions, even in a two-week period.

Dr.  Wendy Slusser  30:32

Oh, that’s very helpful. I’ll go with your take on it. Makes me feel better. So looking at the list of foods that you mentioned in your blog: large amounts of fiber, the tumeric and ginger, foods that have healthy fats like olive oil and avocado, and fermented foods. Now, how can you guide people, for instance, to the yogurts that are fermented? Because I know that’s always sort of a head scratcher? But how do you identify fermented versus, sort of, overly processed yogurt.

Dr. Emeran Mayer  31:07

So this is a head scratcher. There seems to be a general small benefit for a lot of, you know, health-related issues. And so these studies contain a whole variety of different probiotic strains. And as you know, they’re all, you know, from the taxa of lactobacilli, and bifidobacteria. Yet, there’s very few others that you know, that are in commercial use. But there’s a lot of microorganisms that are involved in fermentation of a variety of foods, like in cultures, you know, the Asian cultures – Korea, Japan, China – a lot of things are being fermented, and plant-based foods, and fish, and eggs. Each of these probably has somewhat different types of microorganisms. We can’t really call those probiotics, because there are no studies that have demonstrated the health benefit. In general, the feeling is that, what has happened in our civilized world, hygiene has reduced greatly the microbes that we ingest with our food. So the way I look at it is what all these fermented food products do is they they reintroduce in a controlled fashion, external microbes into our ecosystem within our gut. And so based on that, I think, this was a recommendation to my patients, a large variety of fermented foods. If you rotate them, if you have preferences – some people don’t like kombucha or don’t like kimchi – you can either select the ones that you like, or you can rotate them It’s probably the most plausible way of contributing a health benefit to your microbes. So increasing diversity and relative abundance by external feeding of these organisms.

Dr.  Wendy Slusser  33:02

And I know that, for instance, one way to reduce food waste is to ferment the foods that you might not have quite gotten to when they were at their freshest. So it’s a skillset I’ve never yet mastered, but one of the things that maybe we could do while we’re sheltering-in-place.

Dr. Emeran Mayer  33:24

Yeah, that’s a good idea.

Dr.  Wendy Slusser  33:26

So there’s a few helpful pieces of advice that you’ve already just delivered to us. One is that if you have been heading towards those comfort foods more than you wished you had, or you feel that you’re ready to, sort of, take on a more healthful diet, it’s possible  and plausible that you can improve your microbiome which will then in turn potentially impact your mood. So moving towards this Mediterranean diet of fresh fruits, vegetables, nuts, seeds, healthy fats like olive oil and avocado, and fermented foods, that those kinds of foods, and it doesn’t have to be all that, right. You can still have your brownie or your chocolate chip cookie, just not overly abundant.

Dr. Emeran Mayer  34:15

Yeah, absolutely. And you know, if you travel in Italy, you’ll see there’s a lot of delicious sweets that they have. In general, the quantities, and there’s a big difference, you know,  traditional Italian, or traditional Mediterranean cuisine, is quite different from what you find there today. And also the regions are different, you know, Northern Italy, having a lot more ham and meat products or, you know, Parma, where our friend Professor Del Rio is from. So they’re not really the traditional Mediterranean diet or which was used in the 60s to do these pivotal studies on cardiovascular health. So, yeah, I would say there’s clearly a hedonic component to food and sweets, I’ll give you that. A small amount of that is definitely something that contributes to your well-being and will not have any detrimental effects. It’s, you know, coming back to the cheesecake, I mean, eating a gigantic portion of cheesecake is obviously different from eating a small chocolate that is delicious but is obviously a tiny quantity of the cake. So yeah, I’m not saying that you should stop. And in some ways you could say, it’s the same with meat, you know, somebody, there’s people that love red meat, my son being one of them. I think if you reduce this to a small percentage of your overall intake, it’s very not detrimental, you know. But what’s happening in the Western diet. I mean, this has become like a daily or twice-daily component of people’s meals. Hamburger, which is not just meat, but you know, 60% fat, the more fat the better tastes. I’m definitely, you know, supporting the indulgence of sweets with the Mediterranean diet.

Dr.  Wendy Slusser  34:18

You’re referring to what we’ve worked on at UCLA and other places, that having meat be the condiment, not the center stage, of the meal. So you can get the flavors. that that’s it.

Dr. Emeran Mayer  36:10

Yeah, that’s very wise. Yeah, and you could say this is true in general, you know, the flavors. Yeah, you don’t have to eat four bowls of ice cream to get the flavor. I mean, you could have one teaspoon of each flavor and get the same amount of pleasure. The rest is essentially driven by your mechanisms in the brain having gone wild, you know, because you, sort of, are teasing them with the teaspoons.

Dr.  Wendy Slusser  36:50

Right. So I’ll end with this question. What keeps you up at night?

Dr. Emeran Mayer  36:55

So at the moment, clearly what quite literally is I’m working on my second book, and I’m about two-thirds through and that definitely wakes me up at three o’clock in the morning, because I feel they don’t have enough time to finish. But I would say, you know, what keeps me up. So taking this as a more general question, I think what we’re  seeing now with the COVID-19 epidemic and these differential vulnerabilities of different populations, is something that I find really intriguing. And I’ve written something about it, a speculative piece, and want to explore that further. So what we have seen, you know, the most vulnerable group is the group that has the most, what we call, comorbidity. You know, with the metabolic syndrome and obesity and heart disease, depression, liver disease. I look at this disorders, these metabolic and metabolic-related disorders, as really one chronic disease of our time, this so-called non-communicable diseases. And, you know, as I’ve done the research on this on my book, so you realize there’s clearly a connection between the health of the gut microbiome and the prevalence of these diseases, and the most likely explanation is ultimately, that’s related to the food that we eat. And particularly, as I mentioned this earlier, low-income people or people on the low socioeconomic ladder, eat this predominantly. There’s also racial divides, because those foods, unfortunately, are cheaper than the fresh fruits and vegetables that we’ve been talking about. That somehow there is ultimately a relationship to the gut microbiome, there’s probably many factors that predispose people. But I mean, you can’t overlook this, that this is a problem that most of us are not affected by, probably less than 5%, at most. So you could really ask the question, are we more prone and more vulnerable to these kinds of diseases? And I’m sure, this won’t be the last pandemic that’s come across, you know, the world, have we become more vulnerable to these diseases, because of our diet, dietary habits, and because of the changes in the gut microbiome, with the decreased resilience and resistance to perturbations like that. So I think that’s something I’ve been thinking about a lot. And so obviously, there’s a lot of research going on now, including at UCLA, but I think it’s a big question that certainly, from a nutrition standpoint, and from a lifestyle standpoint, would be worthwhile exploring.

Dr.  Wendy Slusser  39:45

Well it’s just one more reason why we need to try to move towards a more healthful diet for all and really reduce these inequities in our health system and in our health of our population.

Dr. Emeran Mayer  39:58


Dr.  Wendy Slusser  39:59

It’s really unveiled another really big health disparity in our country.

Dr. Emeran Mayer  40:05

Yeah, when you think about it, the cost of this pandemic, you know, is several-fold higher as the cost would have been if you could have intervened early with healthy diets and, you know, lifestyle changes in these most vulnerable populations.

Dr.  Wendy Slusser  40:21

That’s right. Well, to leave on a positive note, there is a program that’s a CDC program called the Diabetes Prevention Program that was studied and published their outcomes in 2002. That does show if you are pre-diabetic, which often also might be the prelude to these other conditions, like hypertension, and obesity, and so forth, if you are pre-diabetic, and you participate in these group classes that are once a month the first four months, once every other week for two more months, then once a month for six months. So 22 sessions, if you even just participate in 10 of them, you will reduce your risk of getting diabetes by 58%. Better than the medication Metformin, which is also very commonly prescribed if you’re pre diabetic, or even diabetic. So there are ways and I think, and a lot of it is related to modest changes in your diet, and your physical activity. And then also there’s a sense of social well-being that’s promoted with these group classes over time.

Dr. Emeran Mayer  41:27

Yeah, that’s amazing. Yeah, I can only support that, I think, the education. And that’s really one of the reasons I’ve started to write books, you know, instead of talking to my colleagues, who often are not that particularly interested in the diet part of gastroenterology. I think it’s to reach as many people as possible and make them think about their diet in a rational way. Because there’s obviously lots of advice out there that’s really not evidence-based and, you know, has commercial reasons behind it. I think that’s the best thing that some of us in academia can do and promote this among students, you know, to start out with, but also amongst the general population.

Dr.  Wendy Slusser  42:09

Yeah, fantastic. Well, Emeran, you’re a real gem for not just UCLA, but for our country and our world. And I’m really looking forward to reading your second book. Your first book was amazing. And we’ll put all that at the end of this podcast so others can learn from your wisdoms. And they’re quite readable too, so don’t worry. He’s very knowledgeable, but he makes it very digestible.

Dr. Emeran Mayer  42:40

Well, thanks, Wendy. It was a pleasure, you know, to add this dimension to our ongoing scientific interactions. I’m really excited about this.

Dr.  Wendy Slusser  42:49

Great, take care.

Dr. Emeran Mayer  42:51

Okay, bye bye.

Dr.  Wendy Slusser  42:58

Thank you for tuning into “Six Feet Apart,” a special series of the Live Well Podcast. Today’s episode was brought to you by UCLA Semel Healthy Campus Initiative Center. To stay up to date with the rest of the episodes in this special series, and to get more information on maintaining your mental, social, and physical well-being during COVID-19, please visit our website at healthy.ucla.edu/livewellpodcasts. Thank you and stay remote.

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