small intestine bacterial overgrowth

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This is a 2-part interview coming next week so stay tuned!

Did you know that many people diagnosed with IBS actually have SIBO (small intestine bacterial overgrowth)?

SIBO is unfortunately a rather under-diagnosed condition impacting your gut that often leads people to struggle for very long periods (sometimes several years!) without a clear answer of what’s going on beyond just being told “you have IBS.”

To be clear, digestive issues like bloating and diarrhea are not normal and can make you miserable. And being told that irritable bowel syndrome explains everything away isn’t really all that helpful especially if you experience severe bloating, diarrhea, constipation, and/or gas – all of which can wreck your life and create food fear (as you try to avoid whatever triggers an issue).

While small intestine bacterial overgrowth is slowly but surely becoming more accepted amongst doctors, we’re still learning more about the different triggers of SIBO symptoms and how it can impact other body systems like your skin (especially for those dealing with rosacea).

My friend and SIBO expert Dr. Ken Brown joins me today! He’s a board-certified gastroenterologist and has been in practice for over 15 years with a clinical focus on inflammatory bowel disease and irritable bowel syndrome (IBS). Known as the host of the podcast “Gut Check Project”, Dr. Brown’s mission is to bridge the gap between medical & natural science, leading to attainable improvements in quality of life for all.

For over a decade, he conducted clinical research for various pharma companies but is now focused on natural solution product development for KBMD Health and KBS Research. Dr. Brown has a clinical and research practice based in Plano, Texas. And he is the creator of ATRANTIL, this FIRST proven solution for IBS and bloating, now available in over 20 countries.

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In This Episode:

  • Why IBS is a total junk diagnosis (and what you more likely have)
  • Fascinating research on small intestine bacterial overgrowth
  • How overgrowth of SIBO bacteria is an inflammation trigger
  • Unpacking methane production in SIBO
  • How food poisoning triggers gut (and skin) SIBO symptoms
  • Antibodies that worsen gut + skin SIBO symptoms


“People are walking around with this benign diagnosis called irritable bowel syndrome. And when people come to me, they're like, well, I'm told I have IBS. I'm like, IBS, in my mind, should be viewed as the warning sign. And the most common symptom is bloating. So what I tell my patients is the bloating you're experiencing, although you think it's normal, because it's been normalized either by you accepting it or a doctor saying, it's perfectly fine, you have to live with it, that's the warning sign that you have gut inflammation.”

“The skin is the outward manifestation. The skin is another warning sign, including acne, eczema, rosacea, psoriasis. All of these things can actually start in the gut, and the skin is trying to say, hey, it's not right, something is wrong. And I do see a lot of people with skin issues. And I have treated a lot of people that have seen dermatologists, and we fix their gut and it gets better.”


Find Dr. Ken Brown Podcast | Instagram | Tiktok



Healthy Skin Show ep. 332: SIBO Symptoms Trigger Rosacea, Psoriasis + Eczema w/ Dr. Allison Siebecker

Healthy Skin Show ep. 019: SIBO-Rosacea Connection w/ Dr. Leonard Weinstock

Efficacy of a Quebracho, Conker Tree, and M. balsamea Willd Blended Extract in a Randomized Study in Patients with Irritable Bowel Syndrome with Constipation


What is Small Intestine Bacterial Overgrowth (And How Does it Wreck Your Skin) w/ Dr. Ken Brown (PART 1) {FULL TRANSCRIPT}

Jennifer Fugo (00:11.703)

Ken, thank you so much for joining me today on the show. It's a real honor to have you here. I apologize, it's taken like 300+ episodes to make this happen, but this is gonna be a special episode about small intestine bacterial overgrowth. So thank you for coming.

Ken (00:25.07)

No, Jennifer, thank you so much for having me on. And in spite of me having to wait for 350 some odd people to go, as I just patiently waited my turn, I'm finally here, thrilled.

Jennifer Fugo (00:35.958)

You're finally here. You know, I will say that one of the coolest things about my audience is that they love to nerd out, not only on skin stuff, but also what can be driving it that's under the surface (like SIBO symptoms and small intestine bacterial overgrowth testing). And that's why I love having conversations about the gut and I feel like, as a gastroenterologist, you have such a different perspective than what I feel kind of is going on. I don't want to throw any conventional doctors under the bus because I get, my dad was a conventional doctor. But I feel like this whole thing about just, everything's IBS, right? It's all about this irritable bowel disease or irritable bowel syndrome. It's all about irritable bowel syndrome.

Maybe we're missing something. So you shared with me a really, actually inspiring and amazing story about how we started to understand what SIBO (small intestine bacterial overgrowth) was. Could you talk a little bit about that journey that you've been on to turn SIBO into what it is today?

Ken (01:38.702)

Yeah, absolutely. So let's talk about IBS really quick. IBS, irritable bowel syndrome, when I was in training, and this is why so many doctors continue with this philosophy, but basically IBS is a trashcan term. If you were to come to me and you have issues, bloating, abdominal pain, and it's relieved with going to the bathroom, you've had it for more than three months, and your workup is negative, you're labeled as IBS instead of having small intestine bacterial overgrowth testing. And so for years, I would see people, and they would come to me quite miserable, and I would do an endoscopy, I would do a colonoscopy, everything is normal, their blood work is normal. You wake them up after the procedure and say, great news, it's just IBS. But they would leave and they were still feeling miserable.

And the weird thing about IBS is that the diagnostic criteria to be IBS is that you have to have pain, constipation or diarrhea, and the main symptom that was there, bloating, wasn't even considered in the diagnostic criteria. Still isn't, actually.

Jennifer Fugo (02:46.29)


Ken (03:04.302)

Yeah, and when you think about it, how in the world can you have opposing symptoms and call it the same thing? You have diarrhea or constipation, we're gonna call it the same thing. So for years, that was something that everyone did. And the treatment, the way that I was taught was, well, Jennifer, if you came into me and you had GI issues and everything was normal, well, it must be in your head. So I was taught to give an antidepressant to people like that. And that was the mainstay of treatment. You would treat the symptoms, like if they've got diarrhea, try and stop them up. If they have constipation, give them a medication to make them poop more, but you're not treating the underlying cause.

So knowing that, heading into it, years ago, and we're talking like 16, 17 years ago, I went to a dinner and a guy named Dr. Mark Pimentel, he was at the dinner discussing something else. Afterwards, we were just talking and he said, you know, in my lab, he goes, I really think I'm onto something here. I believe that IBS is caused by bacteria. And he had animal models that he was working with. This ultimately led to the concept of bacteria causing irritable bowel syndrome, now known as small intestine bacterial overgrowth, SIBO. So he was with a company where they were going to launch a drug, or they were going to try and get FDA approval, for something called Xifaxan. Maybe some of your audience, I know that you had Dr. Siebecker on and Dr. Weinstock on at one time, I'm sure that they mentioned this drug.

Well, I was at the time starting a research division and I was doing pharmaceutical research. So I just jumped at the opportunity to go, well, I want to be part of this novel IBS research. So I was early on seeing what treating bacteria could do for these people that were labeled that had no other treatment. And that's when it all started. And so the drug, Xifaxan, got approved to treat irritable bowel with diarrhea. I'm talking to Dr. Pimentel and he said, yeah, unfortunately we'll never be able to help the person that has irritable bowel with constipation, because it's actually due to a different type of bacteria, something that’s in its own kingdom, called an archaeobacter.

The reason is, is because we're now learning, now you got to remember that this is 15 years ago, I'm following Dr. Pimentel and his research and what he's learning, and he's telling me at the time because I was part of these studies. And he said well, we now know that the bacteria will produce hydrogen, but if they produce methane then the methane will cause the constipation, and we currently don't have anything to help those people.

Ken (05:23.758)

And the reason why is because the type of bacteria, and it's known as an archaeobacter, so it's in its own kingdom, they are very ancient, and modern-day antibiotics do nothing to them. So that's when he said that. And I was in my office, and I just wrote on there methane, and I just started thinking about it. And I'm like, if it's methane, then if we could fix the methane, what could actually be used in humans for this? I'm from the Midwest, and in the Midwest, they were actually trying to get farmers to add food products to cattle, because cattle eat, they have this same bacteria in their ruminant stomach, and they would burp methane gas. And the idea was that when you have these trillions of cattle throughout the world, then it is contributing to the greenhouse effect.

So that's when I went, whoa, is there something else that could be done here? And I was doing pharmaceutical research for years, and that's when I kind of shifted and said, is it possible that there are natural things that the pharmaceutical industry is completely missing here with this new knowledge, that is relatively novel at the time? And that's when I started looking back at animal data, and looking at what different things have been tried to decrease this particular type of organism to decrease methane, and as it turns out, there were some things. And that's when I shifted my pharmaceutical research more into the natural space. And that sort of changed my whole career. I just realized, wow, there's this huge gap between what the pharmaceutical industry is chasing and the natural world that may not be doing the hard science to try and connect it to.

And so that's kind of where I've been, where it's like, how do we bridge this gap? How do we take the pharmaceutical industry and the natural world and see if there's something that we could start helping people? And that's the origin story of what I started doing, looking at different things that could actually get rid of this. And then ultimately discovered that there's these things called complex polyphenols, which are the molecules that make vegetables and fruits colorful. And there's a few of them that very specifically have the ability to get rid of this type of bacteria. And that's where I started, so that's kind of the origin story of how it all began. And Dr. Pimentel, who's still the leading researcher in the SIBO space, and I just kind of took a little left turn and said, well, I think we can do this naturally. And that's where I've been for the last 12 years now.

Jennifer Fugo (07:49.677)

So is SIBO, small intestine bacterial overgrowth, is that a legitimate diagnosis at this point?

Ken (08:02.76)

SIBO is a legitimate diagnosis. It is now recognized with a CPT code and everything. So you can pull it up. Is it widely accepted yet? Not so much in the traditional medical community. I think that the functional medicine space adapted it much earlier, and it is still slowly being adapted, but I'm seeing a lot more of my colleagues that are now accepting it and realizing it. And when Xifaxan got FDA approved for IBS with diarrhea, the funny part is, you have to play the game with insurance. If you say that I'm going to treat somebody with SIBO with Xifaxan, then insurance companies will deny it, because you're not writing for it for irritable bowel syndrome with diarrhea.

So the irony is, when I actually did the original study with Dr. Pimentel, me and my research manager, we're just, I'm one doctor. And unknowingly, I was so enthusiastic about it, I'm like, this is so exciting to be part of this. I had such a huge patient population of people having this, I was enrolling people that were being qualified, that were coming through, and they were all being treated. As it turns out, when you start out doing research, you don't want to be the leading enrolling site ever, especially if you're one person in a non-academic center, because I had an FDA investigator show up at my office with a badge and park himself for two weeks, and just do an under the hood total audit where if something's wrong, there's like, you know, the threats of jail time and all this other stuff. It's like a real serious thing. And, you know, we came through perfect, but that just told me something. I'm like, wait a minute. I'm outperforming one doctor in a city that has a lot of people because I'm widely accepting this idea that you're bloated, constipated or diarrhea. In this case, it was diarrhea.

You could have this issue, that I ended up getting an FDA investigator audit because I was the leading enrolling site. And if you look at all the other sites that were involved, it's the typical ones, it's Cedars-Sinai, Mount Sinai, Johns Hopkins, Mayo, whatever. The paper ended up getting published in the New England Journal of Medicine, but it just tells me the complete underserving of all these people that had digestive issues that were struggling, because they would go to their doctor, they would be told IBS, they’d say, thank you for coming, and that's it. I've labeled you with something, and now you have to walk around with this diagnosis, but you're still miserable. That was the eye-opener for me that really it's like, okay, there's so many people that are suffering from these kinds of things.

Ken (10:58.51)

So SIBO itself, once Dr. Pimentel started putting this out, we now realize that it is markedly underdiagnosed. And one would question that most of the people being labeled as IBS probably are SIBO. If you look at the literature, it's very hard to determine this because everything is studies. But if you have a proper history and the people that I treat, I end up treating even people that have been told that they've had IBS for years and years and years, we treat them and they get better, they've walked around for like a decade suffering from things, by treating them. So the incidence of SIBO (small intestine bacterial overgrowth) in the literature is much lower than what the incidence is on the street.

Jennifer Fugo (11:26.282)

Yeah, and I would also share too that with skin issues, I have seen cases of SIBO with eczema, psoriasis, occasionally urticaria or dermatographia. And also, I mean, not always, it's not 100%, but it's a pretty high proportion of people who struggle with rosacea. And it doesn't matter whether it's ocular, so it just impacts the eyes, or it's facial rosacea, but SIBO seems to have this impact that is not just a gut problem, which is why I find it such a fascinating condition. And sometimes I'll have clients, they'll go to, you know, say, listen, you got to go see a GI doctor, we want to rule out X, Y, and Z. And the doctor's like, here, take some Metamucil or take some here's some Miralax, you're fine, don't worry about it. And it doesn't, I don't know, it's frustrating because I know that these individuals are really committed to getting better, and also it's impacting their quality of life. And yet there's so much inflammation that is driven by SIBO.

And just to share a stat, and we'll put the links to those other episodes where we've talked with Dr. Siebecker and Dr. Weinstock, but about 77% of Rosacea cases are SIBO positive. And as Dr. Siebecker shared, if you are SIBO positive and you get SIBO treatment, the SIBO treatment rate is basically like 90 to 100%. So it's a big deal that this gets identified appropriately. So if that's the case, if we can connect SIBO symptoms outside of the gut, why is it that SIBO, just bacteria, these bacteria, why are they causing so much inflammation in the system?

Ken (13:20.654)

It's so common, other, let's call it extra-intestinal symptoms, like skin, that when somebody comes to see me, and I usually only see second opinions or third opinions at this time, and somebody sits down and they sheepishly have been told that they have IBS by several other doctors, and I'm like, okay, were you ever normal? Well, yeah, I was normal, and then I went to the Dominican Republic and I got sick, and that was for my honeymoon and that was seven years ago, and I've never been right since. I'm like, okay, hint number one, something happened. You were normal, something happened and now you're here. And then I'll say, do you ever feel like you're in a brain fog or have fatigue? Yes. Have you had any skin issues? Well, yeah, as a matter of fact. Any joint pain or anything like that, some will say yes. In that seven years, have you been diagnosed with an autoimmune disease, perhaps thyroid, maybe something else, rheumatoid arthritis? And they're like, yeah.

And so when I take that history on somebody, that explains so much to me. And the reason is, is that, we can get into more detail about how it happens, but once it happens, for your listeners, so basically in the small bowel, so you have your stomach and your small bowel. The small bowel should be relatively sterile. You eat your food, the food comes down, your body digests it, you absorb the nutrients as it goes to the small bowel. In somebody with small bowel intestine overgrowth, SIBO, the bacteria that are there, they sit in an area where there's not a whole lot of movement, the motility. So when you start thinking about it, this could be a motility issue, but whatever, the bacteria are there. Then when you eat, specifically carbohydrates, the bacteria will break down the food before you can absorb it and they produce certain gases. The gases can be hydrogen, hydrogen sulfide, or methane.

Now, while that's going on, the thing is that the small bowel has what's called a tight junction. So your body is built to take in the outside world. So you're a tube within a tube. So the body needs to decide, is this something that we want or is this something that we fight?

Ken (15:36.59)

So, if you were to eat a lukewarm oyster at a party that may have some bacteria in it, your body needs to recognize immediately, oh, look, we have an oyster, we can break this down. And then you have a certain cell that reaches up and samples it and goes, whoa, there's Salmonella in this thing, hands it off to another cell. And this is all going below the tight junction, so right now it's super tight. You've got a little soldier that comes up, takes it, hands it, and then that soldier says, whoa, we've got a problem here. So then they mobilize your immune system to then send out different things that are called cytokines in different cells, and you have immunoglobulins and all these other things to get rid of that bacteria. And then maybe you get a little sick, but you don't die from it and your body gets rid of it, and it's like, yes, thank you, we fixed it.

Now in the setting of bacterial overgrowth, you have these little bacteria that hang out. And the body samples it and goes, ah, kind of good, kind of bad, not sure. Hands it to a cell, cell goes, well, it's not E. coli, it's not Campylobacter, it's not something that we really need to, but you know, it's not right either. So it hands it to different cells, like a mast cell that releases some histamine, then the histamine triggers certain things, then it releases it to a B cell that then says, we gotta get rid of that. So it starts releasing these inflammatory cytokines that go around the body, and these things cause inflammation.

So, over time, this goes on enough that there's enough inflammation that then you end up having a tight junction that then becomes porous, or leaky or permeable, whichever word you want to use. So functional medicine, leaky gut. You say leaky gut to a regular doctor, it doesn't exist, but you could say, well, there's increased permeability. Yes, I agree that there's increased permeability. And once that happens, then you have more of this cycle that can take place. And the inflammatory process continues. The inflammatory process turns on certain pathways that are like a tip of the iceberg. Depending how geeky your audience is, but something called NF-κB gets turned on, and NF-κB is the beginning of a bunch of other inflammatory cascades.

Ken (18:03.086)

So the more that this goes on, we now realize that the more inflammatory cytokines go around, they don't just stay in your gut, they go throughout your entire body. We now know that that inflammation is the root cause of most disease. So inflammation is what causes us to age, inflammation is what ultimately causes us to have disease. But then when you have things like this, your immune system is turbocharged. If you have a genetic predisposition to possibly autoimmune disease, we now believe that that is what sets off that autoimmune trigger, celiac disease, thyroid disease, Crohn's, ulcerative colitis, rheumatoid arthritis, the list goes on and on. It has been associated with causing coronary artery disease, heart disease, and it has been associated with causing liver issues, like fatty liver and liver fibrosis.

It all comes down to this. And so people are walking around with this benign diagnosis called irritable bowel syndrome. And when people come to me, they're like, well, I'm told I have IBS. I'm like, IBS, in my mind, should be viewed as the warning sign. And the most common symptom is bloating. So what I tell my patients is the bloating you're experiencing, although you think it's normal, because it's been normalized either by you accepting it or a doctor saying, it's perfectly fine, you have to live with it, that's the warning sign that you have gut inflammation. That is the proverbial canary in the mineshaft, the old school way of thinking that you have something that's warning you that something's wrong.

And it is that that you have to look at and go, if I'm having these issues, I need to heal my gut because if I don't, at the very least, if you can make it through all this, we now know there was a recent study showing that this epidemic of dementia, when you look at these demented patients, so many of them, the majority of them began to have gastrointestinal symptoms labeled as bloating or labeled as IBS, which included bloating, about 15 to 20 years before. And it's that neuroinflammatory process because these cytokines cross the blood-brain barrier and create neuroinflammation.

So when other patients have come and they've been dismissed, I'm the exact opposite. I'm like, we have to fix this, like, now, now, otherwise something is gonna happen. And that's why. The skin is the outward manifestation. The skin is another warning sign, including acne, eczema, rosacea, psoriasis. All of these things can actually start in the gut, and the skin is trying to say, hey, it's not right, something is wrong. And I do see a lot of people with skin issues. And I have treated a lot of people that have seen dermatologists, and we fix their gut and it gets better. I'm sure Dr. Weinstock, he's published quite a few papers on this where he kind of went down that path early on. He was an early adopter of looking at healing the gut to fix the skin. And it all comes down to the inflammatory process going on in the gut.

Jennifer Fugo (21:15.804)

And if we go back to that oyster, that lovely warm oyster, for a moment, I want to make sure that listeners understand what you were kind of referring to. That food poisoning can happen, whether it's an oyster or it could be like, I got sick, I had food poisoning twice last year. One from some sort of fizzy drink that I will never have again, one of the prebiotic sodas that's really popular, and I had it due to a meal delivery service. So that was the worst one.

Ken (21:41.132)


Jennifer Fugo (22:01.594)

So can you talk to us a little bit about food poisoning? Because a lot of times we blow it off, and sometimes the SIBO symptoms may be really bad and like, you know, coming out both ends, sometimes it might not be as horrible. But I do think that we don't consider what can possibly go wrong if we had food poisoning. And I think SIBO (sall intestine bacterial overgrowth) is one of those things, yes?

Ken (22:19.726)

Yes, and this is where a lot of the science is, what Dr. Pimentel's working on right now, and he's been publishing some stuff on this, and it's really kind of fascinating. What ends up happening is, you get a bug. It could be Campylobacter, it could be Salmonella, it could be even E. coli, and your body recognizes it and goes, Salmonella, let's go kill that Salmonella. So your body mobilizes everything and it produces antibodies, soldiers, that their job is to go out and kill it. And then these memory cells produce more antibodies that are ready, like a reserve army, just in case you ever get this same bug again. You kill it before, you don't have to go through the whole process again. You don't have to vomit and go the other way every single time you get it, which is why when you live in a certain area, you adapt quickly and your body gets used to it. Part of it is because you develop these antibodies that kill the things that could possibly do this stuff.

What Dr. Pimentel figured out is that in a certain percentage of people that get food poisoning, those antibodies happen to be very similar to a protein called vinculin. And this will make sense in a second. So if you were to visualize, if the E. coli, to kill the E. coli, it's a lock and key system. So the antibody forms exactly how to kill the E. coli by attaching to it and then kills it. Now, vinculin happens to have a protein structure which is a little bit similar to that. So when a toxin is produced by these bacteria, called the CDTB toxin, then these antibodies are produced, because that's the trigger to get them to do this, and what they bind to this vinculin protein.

Ken (24:37.678)

Here's the interesting thing. When I said that it all comes down to motility, vinculin is a protein attached to the nerve cells in the intestine. And if you were to think of it like telephone poles or electrical wires, they transmit from one pole to another to another to another and it goes through your whole digestive system. That's called the migrating motor complex. That allows the movement to go all the way through.

Well, when you sit there and bind the vinculin, because you're producing antibodies that are there, it shuts off that electrical current. And so you have this electrical current, comes around, and then it hits a dead spot. And so it just kind of trickles along. You don't have the wave, the muscular wave, that you normally have because the neuro input, so you have a break in the circuit, so to speak. And then there could be another one over here. And depending how your body adapts to it, the theory is that you have this chunk of your bowel, your small bowel, that isn't moving well. And by not moving well, it allows bacteria to grow.

When you go to bed at night, and the key to this is this part, when you go to bed at night, every 90 minutes, your body has something called the housekeeper phenomenon, where its job is to flush everything from your stomach all the way into your colon, specifically to clean house. It's called the migrating motor complex, every 90 minutes. Well, when that's disrupted, when you sleep, you're not cleaning, you actually have this dead spot. And so the bacteria can grow. And that's why it can be such a chronic condition over time.

So it's these antibodies. It's so much so, that I know that some of the research he's doing is looking at it as the 25% of people that have this gastroenteritis from an infection. They're looking at some, the thought that this could be more of an autoimmune thing in these people that keep having recurrent issues. But the key is you have to get rid of the bacteria from that area. So it comes down to this motility situation of moving it. That's how come somebody can be normal, have something happen, and then suffer with it for years and years and years before it starts getting treated. Then insult to injury, when the bacteria are there they're not being cleared out because now you've got this break in the electrical circuit. Then the bacteria can produce certain gases, which do include hydrogen, or methane, and hydrogen causes distension.

Ken (27:01.87)

And the archaeobacter can take that hydrogen and form methane. And methane works like a local paralytic. Very specifically, they discovered that it doesn't allow the intestine to do what's called a peristaltic wave. So you should have this smooth wave pushing everything down like a snake moving. It just kind of sits there and doesn’t, it just contracts. That's where some of the discomfort can come from, and that's where more gas can build up.

And so you've got this two-step phenomenon going on with people that have bad SIBO, especially if they have these antibodies. You don't necessarily need the antibodies to have it happen, but those that have these antibodies tend to have recurrence, and you have to treat the motility portion of it to clear that out. Otherwise, it never quite goes away.

small intestine bacterial overgrowth