Is There a Relationship Between Mood and Diet? (with Dr. Mayer, part 3 of 3)

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.
Transcript
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 ...