Here: Part 3 of 3 with Emeran Mayer, MD, PhD on the mind-gut connection. Dr Mayer talks about the role of the gut in psychiatric illnesses and mood-from a history of forced colectomy in psychiatric patients to an inflammatory diet influencing mood. He answers the question: are we happier when we don’t eat sugar or gluten and should we all be gluten-free? Dr. Mayer is a pioneer of medical research into brain-gut interactions and author of The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health.
David Carreon: Let's also talk about nutrition and diet and microbiology of psychiatric conditions. I know there's been some discussion and some work that you've ended up with around depression and probiotics or depression in the microbiome. How good is this evidence, or what is the relationship between something that we would consider a psychiatric illness and the gut?
Emeran Mayer: As you know, some 100, 150 years ago, there were psychiatrists who are actually obsessed with the role of the colon and fermentation and it led to this unfortunate situation that many psychiatric inpatients in hospitals had to forcefully undergo colectomy and many died because ... There was a phase where psychiatry was actually very much interested in the microbes playing a major role in the psychiatric disease. That obviously has completely disappeared. Today, there's something new that's sort of come up, and that's the role of diet in influencing the nervous system. Felice Jacka in Australia has recently published the SMILE Study. She and her colleagues found that in a randomized study, if they compared the outcomes of patients, I think it was with major depressive disorder, who underwent conventional therapy and their regular diet vs with conventional therapy with a Mediterranean-type diet, there was a significant difference. She has written about this topic.
One explanation of that is related to this concept of an inflammatory diet. We know that high fat, high sugar diets change the microbiota in a way that there's a whole series of events. Increased permeability of the gut is the result of that, increased access of micropolysaccharides or other pro-inflammatory molecules, the gut-associated immune system, which then creates a ... It's not full-blown inflammation, like in inflammatory bowel disease, but a low-grade inflammatory state which then often becomes systemic, so you have circulating LPS levels. My opinion, that's most plausible explanation. As you know, neuroinflammation has been so implicated for depression and other psychiatric diseases as well, so it could well be that diet plays a role in exacerbating it. Certainly not diet is the cause of psychiatric disease, but it's a significant modifier.
Jessi Gold: I've heard people say that when they went on sugar-free diets, or when they went on gluten-free diets that their mood improved. Do you think that's true with what you're seeing in research? Is it totally subjective and they just believe in the diet?
Emeran Mayer: There's certainly, with anything diet, a huge psychological dimension. I think there's few things that have such a placebo effect as diet has. The high-sugar phenomenon, I do believe, because we know a lot about this. High sugar, high fat, it's sort of like opiates. It makes you feel better right away. That's why people almost self-medicate when they're stressed out you crave for something like that. In the long-term, it has these detrimental effects and leads to this low-grade inflammatory state. I think when people say that when they switch their diet to a healthy diet that they feel better, I certainly believe that. In terms of the gluten, that's a whole other story.
As a gastroenterologist, I'm obviously fully aware of the seriousness of celiac disease. It does appear now probably also related to the microbes and the early interaction with the immune system that people develop more and more hypersensitivities and even allergies to food items that 20 years ago nobody ... Like the peanuts and wheat ... If you have that condition, if you eliminate any agent, most likely you will feel better as well, but then you have, it's like 40% of the US population now, who thinks gluten is toxic for them. That's really unsubstantiated. There's nothing that's been found, sort of like IBS, you can take biopsies, you don't find any possible pathological or pathophysiological mechanism.
There was an interesting phenomenon. This really started with a book that came out by a person, an author, won't mention the name, that before was really on the candida connections. This was an early phase that people say all your symptoms, including IBS and fibromyalgia and everything was related to candida and it was due to the high sugar. The same group of people that promoted that like some 20 years ago, are now promoting this gluten-free diet. All the things before there was sugar across all these orders, now it's gluten. That single book, called The Grain Brain, I personally think is responsible for most of that worldwide, I like to call it hysteria, really, which is centered in the US, which is interesting. You go to any other part of the world, people love bread, couldn't live without bread. Whenever I go to France, I ask people, "Have you heard of a gluten sensitivity?" They just laugh at you.
Like many things in science, there may be a certain truth to it. Give you this example about the candida connection, so now that we not just measure the microbiomes, as people have started to look at the virome and the fungi, there is now scientific evidence that people have increased levels of certain fungi, including candida. It would be sort of an amazing thing that 25 years after this non-scientific theories came out that we would support this. That could happen with gluten as well. I have a personal opinion, but as a scientist, I like to say nothing is impossible.
Jessi Gold: Yeah, it's crazy to think one person could write a book and then everyone stops eating bread.
Emeran Mayer: Yeah, it's amazing. An amazing phenomenon.
David Carreon: Yeah. We are running low on time, so we'll have a few more rapid-fire questions and if you can answer in one or two sentences max, we'll go through these questions. Before we do, I also wanted to ask you to say a little bit about the book that you just published. What's it about and who should read it?
Emeran Mayer: It's called The Mind-Gut Connection. It's written for the lay public and I would say it's not just for the lay public, it's also the lay public, but also for a lot of professionals who are not microbiome experts and have not been aware of the science that has involved brain-gut connections and brain-gut microbiome connections. It has a lot of different things in it, different topics in it, from neurobiology of gut feelings, emotional regulation, early life events and influence to diet and optimal health, which is the final conclusion. I think everybody should read it. Even for experts in the area, there's parts in it, including patient anecdotes. Interesting thing to me, now a lot of patients come to me that have heard about the book or read the book and they say, "I am so-and-so in your book. I don't have to tell you much about my symptoms. I'm so-and-so in your book." I think it must have resonated a lot with patients.
Jessi Gold: As a psychiatrist, which sort of patient in my clinic should I recommend would read your book? Is it any illness, anything?
Emeran Mayer: I would certainly say patients with depression, anxiety, particularly if they also have experienced GI symptoms. Autism spectrum disorders, those would be the three main that ... There's also a lot of evidence, Parkinson's disease playing a role. I would say you could probably recommend it to every patient.
David Carreon: Good. I think that sounds like a fascinating book and I'm looking forward to reading it myself.
Jessi Gold: Me too.
David Carreon: First rapid-fire question is, in a sentence or two, what does the field of psychiatry and mental health, where is it that we go most wrong? What is the biggest oversight or mistake that we make?
Emeran Mayer: I don't see patients in a psychiatric clinic. I would say to kind of stop at the neck or not go into the body is, in my opinion, a big flaw. I'm sure there's some psychiatrists who do that. I see the same patients from the opposite end. Most of them have anxiety and depression and compulsive disorders, but I start at the body. I always see the symptoms at the body. They're clearly both there, and I think with psychiatrists, that would be an important lesson.
Jessi Gold: What is your favorite book?
Emeran Mayer: My favorite book, I would say The Black Swan by Taleb. Realizing the complexity of the world and the more complexity, the more interconnectedness and the more unpredictable it becomes. I think our brain functions, also discusses in the book, is a prediction machine that tries constantly to make predictions and if that's done in a linear way, they will almost certainly go wrong. In a complex world as today, it's no longer possible to do that.
David Carreon: What advice would you give to a young doctor, a trainee?
Emeran Mayer: I would say listen to your patient. Most things that the patient will tell you can be explained in a holistic model of brain and body. I would say listen to the patient and don't reject things that don't fit your textbook description. Most textbooks will become obsolete in 10, 15 years. What the patients say, I've experienced this in ideas, research, has stayed the same, and now we're finding so many answers.
Jessi Gold: What is your favorite food and what is your favorite food to recommend to patients to feel better?
Emeran Mayer: While writing my book, I've become a big fan of the Mediterranean diet for various reasons. Since then, since I pay a lot more attention now to dietary factors, it seems there's almost universal agreement that a Mediterranean-style diet, it doesn't have to come from Italy or Spain, many traditional Asian diets have the same composition of 75% plant-based foods and small amount of meat, protein. I would recommend, even in psychiatry now I think it's the same that's in the study showing the slowing of Alzheimer's progression, depression seems to be universal truth to that. It's tasty, you don't have to eat strange things or elimination diets. It's a tasty diet and it's probably one of the best documented health benefits of anything.
David Carreon: What is your favorite species of bacteria?
Emeran Mayer: That's a tough one. There's one, one out of several, that's called Akkermansia muciniphila, funny name. The second name, you can hear the recent connections. They are a bacteria that stimulate especially the cells in intestines that put mucin, mucous, and that's a very healthy thing because the thicker the mucous layer is, the more we're protected from a leaky gut and Akkermansia goes up with a high plant-based diet. It's the food that nourishes these organisms.
David Carreon: Excellent.
Jessi Gold: The last question is, is there a person that you would consider a hero, either living or dead or fiction, somebody that you would consider a hero?
Emeran Mayer: In the microbiome field?
Jessi Gold: Or in anything, really.
Emeran Mayer: That's a tough one. I would say, let's limit it to the microbiome field, Martin Blaser from NYU, who has sort of been the main driving force behind revealing the detrimental effect of antibiotic use, inappropriate antibiotic use on microbial diversity. He's written a phenomenal book, Missing Microbes, which I would recommend to anybody because you will change your antibiotic prescribing behavior dramatically once you've read this book.
David Carreon: Excellent. Thank you for joining us on the show.
Jessi Gold: Yeah, thank you.
Emeran Mayer: It was a pleasure.