The Gut-Immune Axis: Does Your Immune System Actually Live in Your Gut?

Oh, you're wondering if your gut has something to do with your immune system. And I guess we're going to have to talk about it today on Cell to Systems episode 23 because guess what? It does.

Welcome back to Cell to Systems episode 23. And today we have a special guest, Dr. Cynthia Keller, who is a triple board certified physician operating a practice out of Seattle, Washington with over 25 years of experience. We're so grateful to have you on, Dr. Keller.

Thank you so much for joining us. And today, obviously, we're going to be talking about the gut and how our immunity functions out of the gut, and then also how the gut affects the brain and all of these things that are sort of hot topics right now. But I think oftentimes you hear people talk about it, they don't really talk about it the way that this team would talk about it. So, I'm really excited to have you guys sort of chime in and do the back and forth thing and we'll get this thing going. So, Dr. Keller, Cynthia, if you would just sort of kick us off and talk about the gut microbiome and what should people know today?

You know, so it's kind of sexy nowadays to say sort of everything starts in the gut and it's all about the gut, but it's true and it's always been true and that's not just a right now thing. Um, if you I think I like to think about the level of importance of our gut and our microbiome by pointing out that it is really our largest interface with the outside world. And really, I say this sort of jokingly, but I actually think I mean it that maybe my pronoun should be we and us. You know, me and my microbiome. And yeah, I mean, I sort of say that to be funny to like make people understand, but like actually, right, I'm more microbe than I am Cynthia. And so I actually couldn't exist, nor could you without the benefit of what the microbiome make for us. And I think it's sort of almost like spiritually tells us who we are. It teaches us our sense of self, self, not self. Right, this is like a really big deal. What do I accept? You know, in our gut it's so complex, right? We have to accept nutrients, we have to not allow toxins in to the best of our ability, we need to fight bad guys, but we need to allow good guys to stay there to be our microbiome. And in order for all of that to happen, we have to have a sense of self and not self. And so really, like it's so central to who we are and how we interact with the world. So I think even before we talk about the science about the microbiome and the gut, like it's sort of awe-inspiring really, the impact I think it has on us as humans. So start with that?

Wow, that's profound. Um, the notion of there's more microbe than there is us, right? Um, and that sort of notion of what is it—prebiotic, postbiotic, probiotic, or I guess probiotics in the middle. But that's phenomenal information. The way to think about that, Dr. Keller, you know, I'm curious. I've heard from Christie, you know, Christie's been hammering on me about gut stuff for a while. Um, and Craig has said things, and so has Dr. Farie. Who wants to just jump in and sort of take the next step here?

Yeah, this is like the center. I remember back in the day when I first started learning about, you know, alternative functional—whatever you want to call it—medicine, you know, not just sort of breaking out of this like blindness that I had in family medicine and realizing that, you know, the scales fell from my eyes and I saw all the rest of the world. I remember that some of the first people I talked to were the naturopaths, and they were like, "You got to look at the gut. You got to look." I was like, "What are you talking about? That's just where you poop." Like, that's not a thing. But it's everything, right? And my tendency is to look at people who are intestinally asymptomatic and go, "Oh, it's probably not their gut." But that's really not true either. And so it's been interesting to sort of try to discover all the available tools and cuddle up next to a lot of the available tools that are there to look at this. And so there are a lot, you know, you can look at the bugs that are there, and I think that's a lot of what we deal with. But then why is the bug surviving in this particular person? Right, we've talked a lot on this show about the terrain and how the terrain affects everything else that we do and then affects the receptor sensitivity. It affects the way you respond to different interventions or things like COVID being in your environment. And this is the terrain that we're talking about when I talk about throwing seeds on concrete versus throwing seeds in rich, fertile soil. This is the rich, fertile soil or the concrete. And so I can't tell you how many patients we have—I mean, every patient we have to begin at this place.

And so like you were talking about, Cynthia, um, I always tell people this is sort of like your gut is kind of everything from your mouth to your anus, but you have to think about it kind of like a paper towel roll where the outside of the paper towel roll is your skin. The little—we used to call him a doo-doo—the little cardboard tube in the middle is the inside of your intestine. And sort of everything between your mouth and your anus is technically outside your body. You have to sort of think about it in those terms. And then it's affecting everything that we're doing otherwise, right? So who else lives outside your body is affecting the way you process food. The protein that you eat will be different in your body, will behave differently in your body because of its processing by the microbiome, by the changes in receptors inside the body. It's all so interconnected, and we have to start there. Every person who comes to you with fatigue, every person who comes to you with anxiety, every person who comes to you with whatever the situation is, you have to start by investigating both in history and current symptoms and other investigation methods. You have to start by investigating the gut. And people will say, "Oh, no, I feel fine." And then they'll say, "Yeah, but I haven't had a bowel movement in 4 days." So there's a lot of "yeah, buts" that come after if you're not asking the right questions. And so there is a series of questions that we all have a hand in going through to elucidate what we need to be doing and where we need to start. But I always go back and pause at the feet of my naturopathic friends to say thank you for that insight.

I would just like to say too that that is also where I started my sort of more than pediatric journey is, um, there's a big naturopathic school here, right like attached to where I am pretty much. And so way back as soon as I was out of residency, I started going to naturopathic conventions and started interacting with them. And in fact, we're a residency site for Bastyr, the naturopathic facility, even. So I agree with you that they do that way better, and they were also the ones who sort of helped take the veil off my eyes for that.

Yeah, I would really like to say too about the immune system—so I know that that was I think what you initially asked me about, Jock. Oh, microbes, that's what you asked me about. I can do that next. So, I maybe people will not agree with me here—I don't actually know this, but I actually think we're not quite there yet where just getting sort of, you know, a list of what the microbiome—sort of a map of what you currently have—I don't think for me is clinically actionable right now. And I would say that that's what I would push back on sort of what's sexy lately, is I don't think just getting a map of that is all that helpful to me, partly because it's a snapshot in time. And I know that within—I learned this from my naturopathic friends like 20-whatever years ago—that within two days of changing your diet, you can change your microbiome. So it's just a snapshot in time. Also, if I don't really like the makeup, just taking the probiotic that's missing isn't really the fix for that either. So I think what looking at a microbiome list can show you is whether or not you have a good mix or not. But also we don't know what's optimal for one person, and optimal for another person might be different. It's based differently on your diet, on your sort of genetics and all of that. And so who's to say what's even normal? So that is one problem that I have with everyone sort of ordering those tests now and suddenly talking about them. For me, that's not actionable. It, I guess, can be helpful to show to a patient like, "Look, we probably do need to muck around in there," or as proof that the gut isn't ideal at the time. But for me, I don't do a lot of ordering of that. Um, Suzanne and Christie, do you feel differently or is that the same for you?

Yeah, as far as microbiome goes, I totally agree. It's tough to get something valuable there. I'm looking at things like butyrate. A lot of that you can get from the history, but looking at things like butyrate and, you know, calprotectin and IgA and products of protein breakdown.

Yeah, I would say like Christie, you know, was the first one to me when I was talking about stuff. She was like, "Jock, you know, you got to really take a look at—you know, you got to use gut peptides, you've got to use butyrate, all these things that are declining in your gut, and then really about your diet." So Christie, I really would love—you know, we sort of, okay, we've talked about the gut microbiome and hey, there's some immunity there, and we're still not sure exactly what is the N of 1 need. But what are the things that we can do as patients, as people, to make sure that we're heading in the right direction? Christie, you always say this thing I love, which I just think is so brilliant, which is: "If you can't pick it, pull it, or kill it, you shouldn't eat it." So I'm wondering, when we think about that, if we stay on this whole food journey where we're really looking at—I mean, for me, it's all macro-related and micro-related, and I'm doing all this stuff that maybe some people would say is overkill—but how do you see this, Christie?

Well, I mean, first and foremost, Dr. Keller or Cynthia knows how much she means to me. I mean, she has changed my world from the first day I met her. And just how she lectures—I mean, you can always walk away with very practical information that you can implement into practice the next day. Um, for me, I know—what was it, 3 years ago now, Frank, that we had the conference?—and, you know, there was the debate of which system was the most important and all this stuff. And, you know, I had my opinion of which one it is. But it's just of how important—we can't separate gastroenterology from immunology because biology doesn't separate it. Like, our own system doesn't separate it. But yet we're taught in traditional medicine to separate the systems.

But the gastrointestinal tract is where immune education begins. And, in my opinion, one of the most overlooked jobs of the immune system is learning what not to attack. And a healthy immune system doesn't spend all day fighting; it spends most of its time trying to maintain tolerance—tolerance to food, tolerance to the protein, the beneficial bacteria that's coming in, and then just our own tissues. And when that regulation begins to break down, inflammation becomes chronic, and then immune responses become less precise. And it's not necessarily because the immune system is weak; it's often resulting from confusing biological signaling. And the goal isn't to make the immune system stronger; it's to regulate a system that's smarter, that's healthier, that can adapt to these reactive agents that are causing it. And one of the big things where I got so much better with understanding the gut was with COVID. COVID was a good thing in my world as far as really understanding that you cannot—going back to brain inflammation or even cardiovascular inflammation—you're not going to get there if you don't have your gut optimized.

Yeah. Hey Frank, really interesting. Something that just came up and I just have to bring it up to the group here, and I think something to talk about because you said something on my other show when you were a guest just recently. We talk about using any kind of agent. So as a pharmacist, you said, "Hey, any kind of drug, there's the reaction that we're looking for, and there's also the other action that we might not be looking for." Interesting story recently—I mean, not in a positive way—but Bryan Johnson, the guy that's out there doing a lot of things to figure out how to reverse his aging, has now developed an autoimmune issue. Dr. Keller, just like you're kind of talking about, we don't really know, so we're doing all these things that are kind of guesswork, and now he says like his stomach is eating itself. And I was just curious what you guys thought, Frank, what you thought about that.

Yeah, I think one of the biggest things I always talk about is everything's got a side effect, either positive or negative, because a side effect can be positive. And people don't really remember that—they're like, "Oh, side effects are negative." No, some side effects are actually positive, and this is how we develop things like off-label use drugs, because of a positive side effect of something else that created this. Based on what we talked about prior, we are doing things in extremes now. And a lot of the times as we're pushing the envelope as much as possible, it leads to things that are unfortunate. In our experience and experiment, we are finding things and sharing things among each other here. But unfortunately, if you don't listen to your physicians and you are on your own out there trying different things and thinking that your hacking is going to lead into problems, especially when you're dealing with the gut, right? Because the gut only knows what's going to happen if you start injecting or taking or thinking that your diet is the best. It's the most complex thing ever. Just sitting here listening to you guys, I'm like, where do you even start without the right team around you, right? But yeah, I just want to say that because it requires a foundational approach first and then an optimization after. And if you're not optimized and you don't have the foundation first, you can't get anywhere. You can't even do anything afterwards, like taking Akkermansia or glutamine first before you get there. People are just throwing things out there, and it's just more confusing than anything else. But yeah, just to kind of circle back to our last conversation, Jock, yeah, people need to be careful about what they're doing.

It's interesting. I mean, to look at that gentleman's record—Bryan Johnson—and everything that he's doing and how it's so regimented, it's got to be stressful. So right there, that in and of itself is going to contribute to potentially some problems within the gastrointestinal tract, breakdown of mucosal barriers, and so forth. So who knows whether that strict approach that he's following is actually contributing to some sort of downstream negative effects in that way. I looked at this protocol he's espousing and I'm like, "I don't know, man. That seems just extreme and almost like, how would any normal person follow that?" And I think at the end of the day, to the people that are watching this show—the data shows there are a lot of people watching as just regular people trying to find out where do I go, what do I do—I think that's the benefit that we can provide to people today, is sort of like: I love what you said, Cynthia, about the notion of like, "Hey, we're not quite sure yet." So let's kind of bring it all back, if we could, to what can we do today to make sure that we're heading in the right direction with regards to the gut, and how do we take care of ourselves to make sure we're doing what we can do now? And Cynthia, I'd love to take it back to you with that.

Yeah. I mean, so first of all, for me, I just want to say in general to the point of someone getting an autoimmune gastric issue, right, that for me, I've been dealing with autoimmunity in my clientele for my entire career. So that's like not new to me. And it doesn't really matter to me what issue they have; I think of the system as it works really well and it heals itself—the whole body, every cell—when it is sort of in alignment and has the ability to pivot, right? So it can handle stress and then like reset itself. But once it gets tipped, whether that's by genetics or toxins—I have a lot of autism, a lot of things in my practice that are complex—or whether it's something you do to yourself with a stack that's too much or whatever, once you're tipped, you don't just spring right back up.

But the trick then is you just figure out what knocked you over and then start teasing that apart. I'm just not sure that you can do that without someone who has tons and tons of experience. I just want to say that it's like anything can knock you over. Once you're knocked over, it looks often like autoimmunity. And the reason why, if it's in the gut, it looks like autoimmunity is because that's where the immune system is in large part educated. Like we've been saying already, it's really the outside, right? And so if you look at our immune system—and Christie, you were saying this—it's not just that you have to strengthen the immune system, right? The immune system is ready on surveillance to handle whatever needs to happen. So it's sort of ready; it wants to be able to pivot.

So if it thinks there's badness going on in the gut, then it's on heightened alert, right? And it's very good at fighting. Now, you don't want to be like that all the time, but you want to be like that when you're sick. So normally, the immune cells actually stick their little fingers, their little feelers, between the epithelial cells of the gut lining to sort of taste what's going on in the lumen of the gut. So if there's good guys in there, it tastes it and says, "Aha, these are the good guys." So it signals to the immune system—and we could talk about what the cells are that do that, but I think it's more interesting to think about the theory or the process of it, which is that it can say to the immune system then, "Everything is fine here. Everyone just go ahead and like be restoring yourself, be cleaning yourself up, everything's fine." But if it notices parasites or toxins or COVID or anything really in the gut—or gluten or glyphosate—then it freaks out and says when it tastes, it says to the immune system, "There's a problem here. Everyone get on high alert."

And so now the immune system and the cells of the gut lining respond very differently when calm versus when they think there's a threat. And if it thinks it's a threat, then it's going to start to attack things, even self. And I think that is, in short, sort of how we get into trouble with autoimmunity in a lot of cases. And the problem is nowadays the gut isn't well until we get, I don't know, rotavirus or something, right? That's how it should have worked. The gut should have been calm, and then tasted when rotavirus came and fought it off, and then gone back to baseline. But now with our diets the way they are, toxins, I mean just all of it, right?—antibiotics in our food which have changed our microbiome, just everything, right?—the gut is almost never, without help of someone like those of us sitting here, optimal in a way where the immune system knows that it can sit down and sort of be restoring itself and be calm.

Yeah. Can I ask just a really dumb question for a second here? The notion of, okay, well, if you drink alcohol, it's going to affect your muscle protein synthesis for 72 hours, right? The same thing would hold true—doesn't alcohol affect the gut in a pretty negative way? You drink that tasty margarita or two, and next thing you know, you're having some kind of issues within the gut. And how do people survive all of that? It seems like alcohol is everywhere and people are drinking it every day, and it's got to cause massive inflammation and problems in the gut.

Can I just say, I think the toxins in the world right now are so much worse than a margarita if you wanted one occasionally. But I'm also sober for 13 years, so I'm not the one to be telling people to drink. But I would just say, for me, in the experience I have with patients, make good choices most of the time. And if that's true, then the body can handle things here or there. But I'll also open that up to other people.

Well, hey, Suzanne, what about the Think Dirty app, right? What is it? Is it Think Dirty?

It is. It's certainly an option to find out. This is an Environmental Working Group project that put together the environmental toxins that are in our personal care products, right? And it's super helpful. It definitely improves your ability to go to a store and find the products that are going to be less toxic for you than the ones that you're exposed to every single day. And it gives you alternates that you can purchase even from Amazon or Thrive Market that have some better lists of toxins in them for you. And so it's certainly a really great way for you—there are some really obvious, simple things that can be helpful.

Things like using metal or glass ideally instead of plastic in your cooking, preparing your food, and food storage in your home. I switched over everything from plastic Tupperware to using Pyrex. Now, it still has a plastic lid, so I'm careful about not putting it in the microwave. And there are so many pieces. And then, you know, also the kinds of foods that you're eating, and not cooking your oils unless they have a really high smoke point, because the cooked oils are much more toxic even to your microbiome and to the cell walls and to the mitochondrial membranes.

And so everything that you do—and again, it can be really overwhelming when I begin to have this conversation with patients. I can see them shut down and kind of introvert, right? And so for me to be able to say, "Let's pick three things we can do today that can be really helpful for you. Let's find what are three things you can achieve that you will be successful at, because I just want to meet you where you are today." I have a patient who's a lawyer, just runs his own litigation firm, amazing human, but also morbidly obese, diabetes, etc. And every time I see him—which is very rarely because he can't make time for himself, which is part of the problem, of course—when I see him, I say, "What are two things you can do? Can we substitute the jelly bean bowl on your desk for maybe some pepitas that are not roasted? Is that a possibility? Can we substitute them for some fruit snacks instead?" We're just trying to figure out where can we meet you where you are so that we're able to actually achieve some success in moving the needle in one direction, like Cynthia was talking about—get you back closer to alignment.

Certainly the diet is a big part of it, but I think we also—of course, autonomic girl here—can't ignore the contribution of our environmental stressors. And I'd love to talk again a little bit more about the breath things that you were talking about last time, and the breathing and holding, you know, one side, the things that you're talking about, tongue placement.

Yeah. And by the way, I would love to invite Jagel—he's the gentleman that's been teaching me about breathing. And by the way, I've been doing this for, gosh, about three months now, I think. And he just taught me something new a few days ago, which is mitochondria breathing, it's called, in a way to actually improve your mitochondria function, because breathing also enhances mitochondria optimization. And once we get off the call today, I want to see if he's got something to say about breathing and gut health for sure. But yeah, obviously there's mitochondria in your gut, so I'm sure it is also helping, right? But with this gut-brain axis idea—funny enough, you ask me this question because I've seen a difference in my gut health ever since starting this breathing therapy. Yeah, I've been documenting this, and I do 3 minutes of mitochondria breathing in the morning and 3 minutes in the evening as well. It's a different type of technique, and what I've seen the most is the decrease in stress, right? Decreasing stress level, my ability to think clearly, and more importantly, what I've seen is a decrease in heart rate in a more stable position in my heart as I'm exercising more and more. And it extrapolated into better gut health, too, which is crazy that you ask me that question, because I can see the difference, I can feel the difference in the way I process food. Certain things that were an issue before processing tend to be a little bit more tolerable if I don't take my butyrate, if I don't take my gut peptides, if I don't take a lot of my dailies. I'm still able to function better. And I didn't really extrapolate that to when I started breathing therapy, but I think to Suzanne here, there is a link here as well, I'm pretty sure. And it's interesting because it usually happens when I do the mitochondria breathing, which is a little bit more enhanced because you have to really hold your breath for a while—sometimes up to 15 to 20 seconds as you're doing deep breathing. And I don't know if there's an activation there, but if you guys don't mind, I'd love to invite him next time so we can do a little deeper dive in this.

Frankie, was he the guy that was at the pre-conference?

Yes, sir. That's him.

He was fantastic. That guy is amazing.

Yeah, that would be great to have him on.

Oh, for sure. And I think it'll be amazing to just ask him a bunch of questions and, more importantly, see how you can impact the gut, right?—this and other things that we talked about in the past, because I'm telling you, it was the cheapest thing that I've done ever, but it is the most powerful thing that I've done so far.

Dr. Keller, question for you. You mentioned in the beginning of the episode that you're relatively light on the GI mapping of the microbiome, that sort of thing. So say somebody comes into your practice and it seems like they're doing everything right—they're eating a whole foods, nutrient-dense diet, they've got their hormones balanced, they're sleeping adequately, but they're still complaining of really intrusive symptoms related to the gut. It could be, you know, bloating, cramping, what have you. At what point do you start that workup, and what does that work look like for you? And not only that, but outside of just the diagnostic aspect of it, what interventions are you sort of implementing out the gate?

Yeah, thanks for asking. So, first of all, I only do testing if I don't know the answer or don't know what to do, or if I have someone who's not going to believe me unless I show it to them. So I would rather spend money on the treatments. And with the gut, I usually know what I'm doing. So I guess if I was worried I might be missing something serious—like I have this saying at my clinic that we make sure it won't kill them before we rub herbs on it. And that's because—that's one of my Cynthia-isms—because I have a bunch of naturopaths and they were all trained on healing, but I need to make sure it's not gut cancer or something first. But an easy calprotectin—if you were worried like, could this be Crohn's disease and we need to get a scope or do something more serious?—if calprotectin is less than 50 (and that's a stool test), then it's like 98.6 percent or something that you don't have something more serious.

So that aside, first and foremost, I make sure they're not constipated. Way back at the beginning of my career, like maybe two years in, I had a kid with colitis and I sent them for a scope. And she had colitis, but she was constipated. And the GI docs, very progressive of them, said, "Oh, well, we should unconstipate her." And I would say maybe like a third of what I do in pediatrics is poop. This is baseline before I even got interested in functional medicine. But we cleaned her out and then we re-scoped her, and it was completely gone. So I really got it: constipation alone causes gut inflammation, hard stop. And it doesn't matter what expensive, fancy things you're going to use; if someone is constipated, you're wasting your time. That needs to be first, second, third, and it needs to continue. Sometime, if you're interested, I can teach you my GI cleanout that we've been doing for 27 years, because caprophen and gut stuff and constipation is a kid thing.

Anyway, so that would be number one. Second is, when you're eating, in order for the nutrients to be getting in, I think you need to be breathing, Frank, in a good place. You need to chew your food. So not just picking good food, but sort of being mindful about when you introduce it to your body. So that would be really important too.

And digestion: the very first supplement I ever used—this is again, you know, 25 years ago—was hydrochloric acid, Betaine HCl. In general, we've messed things up by using things like over-the-counter acid blockers. That's a disaster for reflux, right? So oftentimes people will come—not really my clinic, because I select for people who wouldn't have already done this—but in general, I'd say the average American who grabs that because they think their reflux is about that, the stomach sphincter does not open to let food into the intestine until it's acidic, right? So if you keep taking antacids, the food rots and splashes, and you might not feel it as much. So antacids are a disaster because now the food is fermenting and rotting, and now you're getting SIBO and yeast and yada yada yada. But if you take hydrochloric acid—there's a more complex protocol I use, but I'll just say here the general person could take two hydrochloric acid pills with their meals. And if it burns the first time, don't do it again because then you have a different thing; that shouldn't happen. But if you take it with most meals, what happens is the body will start to digest the food better. Now particles are getting down, there's less autoimmune or less immune response, more digestion, more absorption, less inflammation. The less the intestine is inflamed, the more it comes to a place of calm and not a place of high alert. And that goes back to what I said before. And what's so magical, the body just freaking heals. And maybe I learned this because I'm a pediatrician, but it just heals if you give it what it needs. So after every bottle, I have them try off of it. And the body wants to—it kind of goes, "Oh, you wanted me to make acid? I didn't understand that." And then it makes acid and you don't need it anymore.

And then the third thing I would say, an easy cheat for people—so one is don't be constipated, be mindful (that's sort of not one of the three), hydrochloric acid (so digesting your food), and the third one would be butyrate is such a good cheat, right? So our happy microbiome in our colon mostly need there to be no oxygen, so they're called obligate anaerobes. And those guys make postbiotics. They eat food and turn it into something we call postbiotics, and maybe the most important one is butyrate. And what those happy microbiome do when I said they help us survive is they make the whole colon happy. It makes our cells happy. They use oxygen, which takes oxygen out of the colon, which makes the happy bacteria happier. So it's sort of like a cheat. So I call it sort of faking it until you make it, right? Ideally, you would already have those guys there, the happy microbes making butyrate, and that would make the whole environment happy and make the immune system calm down. But you can cheat. If I put butyrate in there, then it's sort of like they're there, and it sort of can set up a milieu, a terrain, that better supports them ongoing.

And I had learned from Suzanne one of the first times we met about making rectal butyrate, which was like life-changing for me because I use butyrate a lot. And that was really wonderful. Well, not everyone will let me prescribe rectal butyrate for them, but it's so much better, right? And if you're not going to use rectal butyrate, it really needs to be ProButyrate or tributyrin. It's too big for here, but you don't want butyrate in the small intestine; that's not where it belongs, it'll do other things. You want it to get to the colon. So it needs to be the tributyrin like in ProButyrate form, or rectally. So those three things, I think—if someone didn't get to see me or Suzanne or Christie or someone—if you just were mindful, chewed your food, hydrochloric acid, and butyrate, that would be really amazing.

Pharmacies really hate when you prescribe. My guys are like, "Please don't prescribe rectal butyrate because it takes up the whole pharmacy."

Right. It's so worth it. It is a pungent supplement.

To the point of breathing, Frank, I really wanted to say this here. Remember I just said that the happy bacteria in the colon need to have no oxygen, right? So another thing you can do for your microbiome with breathing is you cannot have obstructive sleep apnea. Because with obstructive sleep apnea, especially like if you have a mask and your mouth pops open, you're getting oxygen into your digestive system, which is going to kill the happy bacteria. It's another link, right?

Wow.

Dr. Keller, thank you so much for joining us today. I hope you'll come back. It just seems like we've barely scratched the surface today on so many things. I mean, this is an amazing—every time I've heard you speak, it's just like I'm blown away. But once again, here we go.

Well guys, once again, as always, it's just such a pleasure and an honor to be a part of this show. You bring so much incredible knowledge to the viewers out there, and the response is obvious. You know, you guys see it—people are really responding well to this. So once again, for those of you if you're new to the show, please remember to like, share, and subscribe. Leave your comments, because we actually read them and we'll respond to them and we'll get back to you and try to help you in any way we possibly can. Until the next time we see you, we hope you all stay well and live healthy.