[INTERVIEW]
Ronda Nelson: There is a certain test that you might be using that has a false positive rate so high that medical specialties have come out and said that it is widely used but unreliable and unvalidated. So before you send your next patient home with a certain protocol, there are a few things that you need to understand. We’re gonna talk about it right now.
Well, hey friends, welcome back. I’m glad you’re here, after last week’s episode where I was quite vulnerable and honest. I hope that some of you found that helpful. I think you did because I was overrun with comments. So I love that you all are embracing this concept and really understanding the power of being together and having community — which, funny thing, when I record these podcasts, I mean, I’m sitting in my office, it’s a Sunday, and I’m by myself with my computer propped up on some books and boxes so that it’s in my eyesight.
I got my mic, and I’m just sitting here talking to you, and I feel like I’m with you. I feel like you’re with me and no one’s here. But that’s just what happens with podcasting and creating this type of interaction. I just always — I don’t know, you’re just all here with me.
So we’re gonna talk about today a test that, as I mentioned, is very, very unreliable and unvalidated. And I — before I tell you what it is, I know you’re hanging on, like, on the cliff. Just a minute. But this particular thing was in vogue about 10 years ago or so, and everybody had this particular condition. I mean, everybody had it, and practitioners were diagnosing this condition like crazy, and everybody had it.
And still, I still see some whispers of it. But it just kind of goes to show you how these ebbs and flows of what the newest, latest, greatest test or supplement or whatever, they kind of come and go, come and go, come and go. Whenever something comes out, flash out of a pan like that, I always think, “Hmm,” my spidey senses go up and I think, “Okay, when is this going to fade away?”
Remember noni juice? Remember mangosteen juice? Remember all that? If you’re old enough, you remember all that. I mean, it was all the thing, and no one ever talks about it anymore because somebody made a lot of money and then the company went under. So I don’t know. I’m a little bit suspicious when it comes to these things.
But all of that to say, today, what we’re gonna talk about is SIBO. And the test that I’m talking about is the glucose test and the lactulose test. So I’m gonna get into a little bit more details about that. But I started thinking about this, it was probably three or four months ago. I actually did an Instagram reel about it, and I said, “You know, we used to be talking about SIBO all the time, and now we don’t talk about it anymore. Why? Is that because no one has it? Is that because patients all of a sudden have no sort of dysbiosis?”
Well, I’ve always said SIBO is simply just a different version of dysbiosis. Now, that doesn’t mean that their symptoms aren’t a bummer. They’re bloating, and they’re cramping, and they eat, and they feel miserable. They’re tired. Bowel movements are constipation, diarrhea, or… And then they go to their doctor, and it’s just all in your head, you know? Or it’s just IBS.
But they’re miserable, and they do — the symptoms do have a clinical origin. It’s small intestinal bacterial overgrowth. And then they came out with their SIBO and their SIFO and their SIMO, and I don’t even — I mean, they’re gonna have all kinds of other names for it, but at the end of the day, it’s just dysbiosis of a type of organism where bacteria are living in the wrong place in the intestinal tract.
So just to make sure we’re all on the same page: SIBO, small intestinal bacterial overgrowth, and it’s basically colonic bacteria that should be living in the colon have been displaced, and they are now living further up, fermenting, doing their normal job that they do in the large intestine, which is to ferment food and create short-chain fatty acids, et cetera.
They’re doing what they’re supposed to be doing, but when you’re in the wrong location, you can’t do that. It’s like getting naked to get in the shower. You do that in your house, in your bathroom. You don’t do that on the sidewalk. I know, bad analogy, but you get my point, right? There are certain places that these bacteria need to live and do their job. When we put them in a different place, it causes problems.
So yeah, that kind of was a funny analogy. I don’t know why I thought of that, but that’s just how my brain works. You gotta roll with me. Okay, here we go. So when these bacteria migrate up or end up in the wrong place, in the small intestine, they’re supposed to be in the large intestine, they ferment the food before it reaches the colon ’cause they’re doing their job. There’s nothing wrong with them. They’re just doing their job in the wrong location. When they ferment that food, they produce methane or hydrogen gas, and that causes the bloating and the distension and either diarrhea, constipation, malabsorption, et cetera.
So it’s not that there’s nothing wrong with them, it’s that we understand what the pathology is. We understand because we know what the mechanism is. But if we’re going to treat it and address it, we have to understand, A, what it is, and if we need to test.
So early on, they had this test. It was a lactulose breath test and a glucose breath test. And they did a lot of — they came out of the flash in the pan, like, “These are the tests that you need to use.” But the inconsistency with those tests, I saw it 10-plus years ago, when sometimes people were positive, they would be positive, and they had no gut symptoms, because they were sure, ’cause they heard online or their friend has SIBO, so, “I’m a little bloated, I must have SIBO, too.” You guys that are old like me, you remember how all this went down.
But in 2024, they did a landmark study. This study was endorsed by both the American and European Society of Neurogastroenterology and Motility. And what these two societies, one in Europe, one in America, what they both said was, as I quoted earlier, that these tests are widely used, the glucose and lactulose tests, but they’re unreliable and unvalidated, and they said in their study that they led to injudicious use of antibiotics.
And so when they went back, the way that they got this data is they went back and they looked at the lactulose breath test, and they found that it had a — sit down, get ready for this — sensitivity of 42%, 42%, and a specificity of 70%. Whereas the glucose breath test had a sensitivity of 54% and a specificity of 83%, so it was a little bit better.
Now, just for context, if you’re not a mathy person or it doesn’t make sense to you: if there’s something that has 42% sensitivity, that means that it’s missing over half of the positive cases. So we have a lot more that are being missed than are being captured. That’s with the lactulose breath test. When you have 70% specificity, that means that 30% are gonna have positives when they don’t have the condition.
And so there’s gonna be a lot more false positives, especially in patients who’ve had any kind of previous GI surgery. So the false positive rate is kind of the big thing, because we get a bunch of people that are tested, they’re showing up positive, especially if they don’t even have any symptoms. And then we do these tests, and then they show up positive.
There’s another issue with the lactulose test, and that is that it depends on the lactulose solution reaching the colon within 40 to 70 minutes. Okay, fine. So that’s all well and good. But what happens if the person has a real fast intestinal transit time or they have a slower transit time? There’s some variability there. You have no control over when that solution’s gonna reach the large intestine, so really it’s more of a test of transit time than it is anything else, and the faster the transit time, the higher chance of a false positive. A slower transit time, higher chance of a false negative.
So the lactulose test, we need to pitch it. It’s just not working. And I’m gonna get into how to fix this, by the way. I won’t leave you hanging. I’m gonna give you a few solutions here when we get done. So what we want to do — the gold standard is an endoscopy. They’re gonna do a jejunal aspirate culture. That’s the gold standard. But the problem is, is that we aren’t doing that in functional medicine world. It’s expensive, it’s not standardized, and it’s not available widely, especially to functional medicine practitioners. So nobody ordering any breath tests is ever going to be able to compare it against that gold standard.
So let’s talk about prevalence for a minute. In the US population, it’s estimated that about 20% of the population will test positive on SIBO breath tests, about 20%. In patients that have IBS, that positive is 31 to 84%. So interesting that we have a higher percentage of people that test positive for IBS, and I would argue that SIBO can have symptoms similar to IBS.
But it depends again on the diagnostic method. So they found that with IBS, that the lactulose breath test, the one that we’re gonna throw out on its ear, it had a range of 28 to 84% specificity, and the glucose test was 2 to 31%, and with the aspirate culture was 2 to 6%. All of those numbers basically say that there is a huge variation between 2% and 84%, depending on the testing method — not because SIBO is more or less common. It’s because the test drives the number, and the test results determine whether the patient gets the right diagnosis or not.
According to the lactulose and the glucose test, basically almost everybody has SIBO, and when you do the culture test — I mean IBS, the culture test — nobody has it. It’s 2 to 6%. So it’s a testing reliability problem.
So here’s where the clinical workup happens. This is the hill I’m gonna die on. I’m adding more and more to my list of hills. SIBO is not the primary problem. I have said that from the beginning. It is just dysbiosis. The biggest question is, what went wrong to cause the dysbiosis? Those colon-originating bacteria didn’t just magically wind up in the small intestine. What happened? What went wrong? Where did the physiology break down?
There is always going to be a reason that the SIBO or the displaced bacteria — something’s up with the bacteria. There’s dysbiosis in the small intestine. How is it that the small intestine lost its ability to keep them out? Think about that. How did the small intestine lose its protective ability to keep its environment pure and protected? That’s what you have to find out. It’s not that they tested positive, didn’t test positive, lactulose, glucose, blah, blah, blah. Doesn’t matter. The question is, what went wrong? This is not normal, so what went wrong?
There are a few reasons — six reasons. I’m gonna give them to you one at a time. So if you’re not driving, you’re not doing anything dangerous, operating heavy equipment, you might wanna write these down.
Number one, dysfunction in the migrating motor complexes. Now, if you’ve never heard of them, in short, these are basically like a housekeeping wave, okay? It’s a muscular contraction that sweeps residue, bacteria, debris from the small intestine down into the colon in between meals. When a patient is snacking, that MMC wave has to start all over again.
So we wanna leave three to four hours in between eating so that the MMC wave, migrating motor complexes, can start and finish. Think of an earthworm. It’s gonna go and go and go and go, and then it stops. It’s a wave, and it has to complete. If you eat, it starts the wave. As soon as — it gets maybe a third of the way down, and then the patient’s snacking again, the wave stops.
Listen to me here. You’ve got to get this. Make yourself a visual picture. The wave stops. The MMCs stop because now we have food in the mouth. Now the MMC wave goes, “Oh, food. Okay, let’s start over,” and it starts all over again. What happens at that point where they stop? We got a log jam. We’ve got debris, food, bacteria that may be meant for somewhere else in the body where they’re supposed to go inhabit, but they stopped because the patient is snacking all the time.
And so the MMC wave never gets to complete its housekeeping cycle. It’s like starting a dishwasher, and you keep opening it up, and you start it again, and you start it again. At some point, nothing’s gonna get clean, nothing’s gonna get completed. So when that MMC wave is impaired, the bacteria that would normally be swept out can accumulate in the wrong location.
Cedars-Sinai did a test, and they found that people with IBS have these cleansing waves 70% less often than people without IBS. So there is a very strong correlation between this state of dysbiosis or irritable bowel — something going on in the intestinal tract — with this MMC wave.
The second reason that will influence that MMC wave, besides this eating issue, is post-infectious damage. So like post-infectious food poisoning. And what happens is when you get that acute gastroenteritis where there’s inflammation and there’s diarrhea and pain and all the things that happen with food poisoning — again, they found, this is Dr. Mark Pimentel, he did this research — that there were certain types of bacteria that the immune system produced antibodies against, something called vinculin.
I know I’m getting a little technical here, but some of you nerdy people like me like it. But this is the protein that is needed by this MMC wave. So now we almost have like an autoimmune response post-infection, post-gut infection, food-poisoning-type infection, that can interfere with the MMC wave. So these antibodies cross-react with the nerves that control gut motility, and it impairs the wave and creates conditions in the gut for the bacteria to overgrow. So one in nine cases of food poisoning leads to IBS, so we know that there’s a correlation.
So the questions that you wanna ask your patient are: have you ever had food poisoning or traveler’s diarrhea? Did you feel like you fully recovered from it, or has your digestive system never been well since? If the answer is yes, there’s a possibility that that MMC wave is impaired, and you cannot treat the SIBO without supporting motility. You can do the things to get rid of the bacteria that might be overgrowing with the normal protocols that we would use, but if we don’t get the motility working, that’s a problem.
So reason number two, hypothyroidism. Yes, I said it. Here it is. So we know that thyroid hormones are strongly associated and needed for adequate gut motility. So when thyroid function is slow, so hypothyroid, the motility of the gut slows, transit time slows. That means the MMC wave is weakened and the small intestine doesn’t have the same ability to clear out the bacteria that might go there.
They found in an Italian study that I saw that 54% of patients with hypothyroidism tested positive for SIBO compared to 5% of the controls. So there’s that. Now, testing again could have been false positives after what we talked about earlier, but I think it’s worth considering. The American Endocrine Society, their annual meeting in 2025, they said they found the risk of SIBO in hypothyroid patients — get this, pay attention — 2.2 times higher than in matched controls, and 2.4 times higher with Hashimoto’s.
Let me say that again. The risk of SIBO in hypothyroid patients is 2.2 times higher, and in Hashimoto’s it’s 2.4 times higher. So there is a very strong correlation between thyroid disease and issues with SIBO. They found that patients that are on levothyroxine or other thyroid replacement hormones had a lower risk of SIBO, probably because those thyroid hormones are more available for the body to use. And there were probably three or four other studies that basically confirmed the same thing from different institutions.
So here’s what you wanna ask your patients. You wanna ask them, “Has your thyroid ever fully been worked up? Have you had more than just a TSH?” The stupid TSH is not even thyroid hormone, right? “Have you done a full comprehensive thyroid workup?” If they have gut dysbiosis, quote, “SIBO” — this is before you diagnose them with SIBO, let’s figure out what the underlying cause is, right? So we need to work up their thyroid. If they haven’t, order those thyroid tests.
Reason number three, hypochlorhydria and PPI use. Stomach acid is the number one barrier against bacterial overgrowth in the GI tract. The acidic environment is supposed to destroy the majority of unhealthy or unwanted bacteria before they ever get to the small intestine. So if the patient doesn’t have robust upper digestion, a low pH in the stomach, good enough acid, then the bacteria are gonna slip on through, and they’re opportunistic. So of course they’re gonna go find a home where they can eat food and ferment it. Why would they not, right?
And then the PPIs — the mechanisms are a little different, but the end result is the same, which is that it alters the pH of the gut. When it goes up, now the bacteria come through because there’s no acid. So it could be Tums, Pepto-Bismol, all the things, right? Acid, PPIs, acid blockers, H2, whatever. You have to know that they’re interfering with the pH of the stomach, and the bacteria can survive that environment and make it on down to the small intestine. So then you would wanna go support that upper digestion.
Diet is also a consideration here. So there’s the low FODMAP diet, there’s the specific carbohydrate diet or SCD diet, and I’ve always promoted those because what it does is it removes from the diet the foods that could add to the bacteria or feed them so that they ferment. Basically, it gives carbohydrates that are absorbable higher up in the small intestine, and that’s all great. It’s good to do that if you need to, along with your killing or antimicrobial protocols, but we have to remember that’s not the solution. The solution is finding out why we had the bacterial overgrowth in the first place.
So here we go. Ask your patients, “Have you been on a PPI for three years or longer? Have you had bloating or digestive symptoms lower down since being on that PPI?” Because that could be a clue, and then you’ve got to get them off of the PPI, with their doctor’s permission and blessing, of course.
All right, number four, structural issues. We can’t rule this out. Adhesions, diverticuli, strictures, surgeries — all of those create anatomical conditions where bacteria can hide and accumulate, basically bypassing the normal physical clearance mechanisms. So you wanna just ask the patient if they’ve had any significant surgeries. Could even have been an appendectomy or a C-section, right? C-section, bowel surgery, cholecystectomy, had their gallbladder removed. Those patients have a higher risk for developing SIBO because it changes the way that the bacteria are able to move down through the GI tract.
Number five is opioid medications. Opioids slow intestinal transit. Ask anybody who’s been taking them for pain, and you’ll know constipation is a big deal. So if the patient is either on them or has been on them, you just wanna ask, is there any opioids in their medication history?
And then number six is chronic stress. We know that cortisol slows digestion, right? It puts us in a sympathetic state, so we need to make sure that cortisol is being managed. The person who’s got gut issues and they’ve had a lifetime of chronic stress — well, of course, they’re not breaking down their food well. Why would they? Because the body’s in fight or flight. It says, “No thank you, not gonna worry about digestion, I gotta run from the bear.” So there’s lots of research and study on that. I don’t have to give you all of those.
So I think that what we have to remember is that those six things are the most common potential underlying causes, and a patient could have more than one. So you have to be able to rule that out.
So the treatment — how are we gonna treat this now? My number one is going to be absolutely we have to kill the bacteria. But if you don’t identify as best as you can what the underlying cause is, the problem is that the patients often relapse. There is a — in current treatment models, even within the functional medicine space, the relapse rate is 40 to 70%. Even with rifaximin, which is an antibiotic that they’ll use conventionally, in conventional medicine, and even with herbal protocols. It’s in both worlds, Western medicine, alternative medicine. So 40 to 70%, and 40 to 45% of those will relapse within the first nine months of successful eradication, meaning that they’re gonna feel great for nine months.
Well, how’s that gonna work out for your practice and your reputation? If you spend nine, six months, let’s say, working on dysbiosis, patient is clear, all good, everything is great, and then it comes back — they’re gonna be mad at you, my friend, for not doing a good job, because we do the antimicrobials and it kills the overgrowth, but it doesn’t fix the MMC wave, it doesn’t restore stomach acid, it doesn’t address their long-term use of a PPI or thyroid, hypothyroidism, or the autoimmune vinculin damage because of food poisoning. It doesn’t address any of those things. You’ve got to figure out what the underlying cause is.
So once you do, you need to, A, get rid of the bacteria. You’ve got to institute the herbal or antimicrobial protocols, whatever it is you’re going to do, address what you think the underlying cause is, and then you can start doing the sweeping. So I like to think of the MMC wave — I kind of do that after I’ve gotten the gut bacteria sort of under control. You can do it first, but I think it just kind of moves things along. I would rather get the bacteria under control, deal with the PPI issue, get their thyroid lined out, find out if there’s any food poisoning, opioid use, whatever it might be of those six things — you wanna rule all of those out — and then I kinda like to add in the MMC once I feel like I’m on top of it a little bit.
So a 2025 study, these are all pretty recent, found that treating SIBO holistically or from an alternative perspective and combining it with investigating what the root cause is resulted in a clinical improvement of almost 75% of patients, even when the breath test showed normal in only 40%. There again, another marker to show that the breath tests just don’t work. Breath tests, normalizing a breath test and clinical improvement are not the same thing. Absence of symptoms and a positive or negative breath test doesn’t mean anything. You just need to kind of toss them out.
If the patient is like, “I really wanna do a test,” if you have to choose between the two, definitely choose the glucose test. Don’t choose the lactulose test. Just don’t do it. It’s not worth it. The glucose test is slightly better.
So what does this look like? I would say first you’ve got to take a good history. So obviously you need to be asking about food infections, any kind of gastroenteritis that happened along the way. You need to be asking about abdominal surgery. You need to be asking about their thyroid, opioid use, their stress history. Was there death? Was there trauma in their family? Were they abused as a child? We need to look at all of that, and then obviously the pattern — what are their digestive symptoms? Not only do they have bloating and discomfort, but do they have diarrhea or constipation, or is it alternating? That can sometimes tell you what the pathogen is. Bacterial tends to be more diarrhea if it’s SIBO. If it’s methane or SIMO, that tends to be constipation-type bloating, constipation symptoms. So you could do that, but I think at the end of the day, a lot of times the treatments are very, very much similar. I have a whole lesson on this in Clinical Academy — a whole thing where I go into deep detail about what to do for which one.
Number two, again, if you’re going to do a test, please, please do the glucose test. Don’t do the lactulose test. And then don’t forget to treat the underlying issue. So some of my favorite supplements for this is garlic — works really well if it’s yeast overgrowth or bacterial overgrowth. I like to do that. It even works well with the methane. So garlic, I get mine from MediHerb. I love their Garlic Forte.
Another one is oil of oregano, really good for SIBO when there’s bacterial overgrowth. Works very well. I would pulse dose it, not do it straight, because we don’t wanna create bacterial resistance. Oil of oregano is antimicrobial, antibacterial. Also berberine is good. They found in a randomized control trial that they compared berberine to rifaximin in about 180 SIBO patients, and they found that it was comparable to rifaximin. So berberine can be used. It also helps with blood sugar. Berberine and neem — there was some other studies that show berberine and neem, you can get that as an essential oil or in herbal products. But for hydrogen-dominant SIBO, those two seemed to be good. Garlic and oregano seem to be better for methane and bacteria.
So then you could add the MMC support. The only company that I know that has a specific MMC product is Gaia, and it’s called MMC Restore. I have used it, and I love it. It works every single time. So big shout-out to Gaia and their product, MMC Restore. It just helps to kinda restore that wave. Ginger is a prokinetic, so you can have the patient either eat ginger, drink ginger tea, that kind of thing.
For hypochlorhydria, I’m sure you all have your favorites. I like Zypan and digestive bitters. And you could even add some kind of a digestive enzyme, and there’s lots and lots of those. You also might be thinking about something along the lines of CellCore, which I love — their biotoxin binder, anything that’s gonna help support drainage. Those are all things to kinda mop up that environment.
But what you wanna do is make it appropriate for what you think the best — what their presentation is. And here’s the thing: if you do it for a month and they’re not getting results, then just switch it up, because they might be more methane dominant than bacterial dominant, or it might be a yeast thing. That’s why I like to use supplements or herbs that kind of overlap. They’re more broad rather than getting into the weeds about doing a nuanced protocol.
So remember, don’t diagnose SIBO from symptoms alone. Don’t use just the lactulose breath test. Some patients don’t do well on probiotics — that’s actually a clue. If they take probiotics and they feel worse, it’s almost always because there’s some kind of overgrowth going on. And then start your antimicrobial protocol, but make sure that you’re not waiting too long to start that MMC or get that motility working. I usually wait a little bit because I don’t wanna overwhelm the patient. I wanna get in there, but I’m kinda coming in with that MMC shortly thereafter. And then make sure you address the PPI. Don’t start a SIBO protocol if you’re on a PPI, because you’re just not gonna be effective. And don’t assume that a negative test means there’s no problem.
I know I kinda went fast on all that because we’re running long. I didn’t wanna leave you hanging, though. So you might wanna go back and listen to this episode again. There was a lot of gold in here. Remember, there are six underlying reasons that can contribute to bacterial overgrowth, whether it’s methane, bacteria, yeast, whatever it is. But the bigger question is, why did the small intestine — why was the body not able to protect itself from the bacteria that are somewhere else, right?
Also, another thing that’s not in here is the ileocecal valve. There could just be migration, just normal migration back up the tube, and so we wanna look and make sure that the ileocecal valve is working as well.
[CLOSING]
Ronda Nelson: So that’s what I got for you today. SIBO, it is a thing. No one really talks about it. We just talk about it now as dysbiosis, which is fine. But I still think that those six things are underlying issues when you have someone that has bloating, alternating constipation, diarrhea, pain after they eat, they start feeling really miserable. You’ve got some bacteria that have dislocated.
So if you love these kind of clinical insights, as I mentioned, I have a full training on this inside Clinical Academy. You can go there, join rondanelson.com/clinicalacademy. It is my clinical brain that teaches you how to implement what you know in real life with your real patients when they’re sitting right in front of you. It gives you the protocols, the strategies, the understanding, the knowledge, the context for why something is happening. There are well over 100 different lectures. There are multiple different conditions being talked about. It is literally my clinical brain in an online format. So there you go, rondanelson.com/clinicalacademy.
Like, subscribe to the channel. I love having you all here. I really do love being on YouTube as compared to being on a podcast platform, so thanks for following here. I’ll see you next week.
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