What We Got Wrong About the Gut Microbiome (And What's Actually Right)

**Dr. Emeran Mayer** (0:00)
But I think to see the microbiome as a master translator in our bodies, that translates whatever goes on around us, comes into the diet, and which comes to us through our mind, because that goes down to the microbes as well. The microbes translate this information into the body's own language. And if that translation has an end result of a pro-inflammatory neurodegenerative message, then that's where the disease comes in.

**Dr. Mark Hyman** (0:27)
Welcome, Emeran, to the podcast again. Good to have you back.

**Dr. Emeran Mayer** (0:30)
Thanks for inviting me, Mark, it's a pleasure, honor.

**Dr. Mark Hyman** (0:33)
Well, it's fun to talk about poop, which is my favorite subject. They used to call me Dr. See Every Poop when I was at Canyon Ranch, because I used to look at stool tests all the time, and I wanted to see stool tests on every patient. But you're an MD, you're a gastroenterologist, you're a scientist, you've been studying the microbiome for a long time, and you've written a book about it that we talked about on a previous podcast, which I'd recommend people listen to, The Mind-Gut Connection, a really powerful book. This is sort of a 10th anniversary edition that's come out, How Hidden Conversations Within Our Bodies Impact Our Mood, Our Choices, and Our Royal Health. I think science has finally come up with a simple idea, that what's happening in your gut is affecting every single system in your body, and is related to almost every disease you can think of, whether it's depression or dementia, whether it's cancer or heart disease, whether it's diabetes or multiple sclerosis, everything, in some way or another, has a tie back to the microbiome in the gut, and even this whole new nutritional metabolic psychiatry field has emerged since then. I think systems biology is now coming more into the forefront of understanding the body as this complex network of systems, not this structured organ-based medicine that we have. It's based on specialties that has nothing to do with actually how the body works. It's just an artifact of the salias dissecting the body. Now, we're in this field of like, well, what do we know about the microbiome now? What can we do to assess it properly?
How do we actually treat people focused on the microbiome? A lot of your work is about this in your new book, which is really an incredible manual. It's more like a practice manual called The Mayer Model, Optimize Your Health and Wellness with the Brain-Gut Connection is out now.
It's a really good practical application of this, and understanding how we can bring our healthy microbiome back into gear. So maybe we can start out by having you kind of frame just a scope of the problem. Again, how big is a problem of the microbiome in health and chronic disease in 2026, particularly in America?

**Dr. Emeran Mayer** (2:37)
Yeah, I would say, I mean, just building on what you elegantly summarized, you know, that we're changing our view of looking at these interacting systems. So it's not just the microbiome, it's not a particular microorganism. It's really the system in which these elements interact with each other. I think that, so I've kind of, you know, from the initial enthusiasm, well, I would say from initial skepticism 10 years ago, when these first papers came out about how, in mouse models, how changes in the microbiome can alter emotion-like behavior, which I questioned because we had done decades of research on these brain-gout interactions without the microbiome and had a pretty good idea of how they work. So I went to my initial skepticism to, you know, jumped on the bandwagon, was totally enthusiastic. This is going to explain everything and we can cure all our chronic non-contagious diseases with manipulating the microbiome.
And I've kind of come back to a much more careful view of this, you know, that the microbiome is a…
We have a lot of evidence from animal studies that there is a causal relationship between what the microbes actually do and what the result is. We don't have that evidence, the same evidence in humans, unfortunately. You know, we still have to rely on correlations, epidemiological correlations. And so I like to keep my skepticism in terms of, you know, can we actually deal with this, with our health crisis, just focusing on the microbiome? You know, can we just tell people to take this or this probiotic or symbiotic? I just don't think it's as simple as that. And the reason I'm saying this is because if you look at reality, you know, there's so many people, like topic of longevity, a lot of people live into their, become centenarians, live into their hundreds. If you look at these personalities, I doubt seriously that they paid attention to any of these things that we're now propagating from exercise to, you know, the healthy diet. There's also, you know, good evidence that many of the negative factors like traumatic stress by changing the microbiome has this long-term effect because a lot of these centenarians are actually Holocaust survivors have gone through the most severe early life stress, you know, based on a simple model, you would say, so what can we do? I mean, just coming back to your question, the interventions haven't really changed that much. You know, this is one thing when I wrote this anniversary edition and reread the book from 10 years ago, there hasn't really been that many novel, if any, practical recommendations that we can give based on the science. We know a lot more about the system now, but the main, the mostly effective interventions are basically lifestyle and diet. You know, that's kind of a paradox. And I don't know if that will change, if he ever will come to, I mean, it's kind of another topic we can talk about that I mentioned in the anniversary edition. There's this new field in science of these bioengineered probiotics, which basically you can interfere with specific functions in the body. We don't really have those yet in hand for clinical use.