SIBO Testing Considersations

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SIBO Testing Considerations with Dr Nirala Jacobi


SIBO Testing Considerations with Dr Nirala Jacobi

it's been about five years now that we've launched our very first episode of The SIBO Doctor Podcast and have had some amazing guests and episodes over these last five years. It'll be five years I can't believe it in January 2022. So I thought what I'd do today is just revisit the testing considerations in SIBO and see if anything has sort of developed over the last five years, because it was one of our first episodes back in 2017. So what I want to talk about is testing considerations in SIBO and more or less IBS as well. Well, I'll talk a little bit about breath testing and many of you who are following the SIBO Dr. Podcast are no strangers to breath testing, this is our primary test for us to diagnose SIBO.

I want to talk a little bit about retesting also and the benefit of retesting after having been treated for SIBO and I want to talk about the ibs-smart testing, which is basically a blood test for the cause of SIBO. If you have a relapsing SIBO and also a little bit about SIFO and the benefits or the shortfalls of stool testing and also intestinal permeability testing. So testing is really helpful, if you have functional digestive disorders, we often do a variety of testing to understand whether or not you have SIBO or if you have some sort of microbiome disorder or digestive dysfunction where you might not be making enough enzymes or if you have fungal overgrowth. So I do a lot of functional testing in my clinic because I see primarily digestive disorders. I have a clinic called the Biome Clinic in Australia, where we basically treat patients with digestive disorders and I couldn't do it really without testing and understanding underlying causes and contributing factors and all that goes along with it.

So I'm a big fan of understanding what I'm actually treating and also looking at the progression and improvements over time, especially when we're talking about microbiome restoration. So when we talk about SIBO really the only tests that are available to us are the breath tests and the blood tests for the antibodies to the migrating motor complex, which I'll talk about in a moment. What's sort of changed over the years is the testing window that we look at in order to diagnose SIBO. But just to recap what breath testing is, breath testing involves one to three different substrates of the testing sugars, whether that's lactulose or glucose or fructose depends on what your practitioner has ordered, but the most popular substrate is lactulose followed by glucose and fructose. So typically you're given a test kit where you do a little bit of a prep diet, then you do an overnight fast and then you consume the sugar, like I said, whether that's lactulose, glucose or fructose, and then you test or sample your breath every 20 minutes, preferably for three hours.

And what we're looking for is whether or not there is a rise in hydrogen and to be positive for SIBO, you need a rise of hydrogen of 20 parts per million within the first 90 to a hundred minutes. Some practitioners extend that to 120 minutes, but really the vast majority of people should be interpreted within the first 90 to a hundred minutes. And I think 120 minutes for a lot of patients does fall into the category of large intestinal timeframe, which is outside of the SIBO diagnosis. So ideally 90 to a hundred minutes, unless you have a really documented case of either gastroparesis, which is a condition of very, very slowly or slowed gastric emptying or stomach emptying.

So meaning that the sugar just sits there for longer, but the majority of people really should be interpreted within 90 to a hundred minutes. So it's 20 parts per million for hydrogen to be considered positive. And then you have methane, which is the second gas that we're testing for in these breath tests. And methane typically is relevant in a constipated patient. Some people have methane normally without any symptoms of constipation, but people that are constipated typically we see methane levels higher than 10 parts per million throughout the test and sometimes very, very high levels of me methane and sometimes no hydrogen and only methane. So Intestinal Methanogen Overgrowth is a little bit trickier to interpret in terms of SIBO because when you only have methane, it still means hydrogen is present because you need hydrogen in order to make methane. But if you have no rise in hydrogen, it's harder to interpret how severe the hydrogen may be.

So IMO is really, or Intestinal Methanogen Overgrowth is very relevant in those that are constipated and also act a little bit as a sort of storage for hydrogen. So sometimes what happens when we treat SIBO in a patient that has both hydrogen and methane and we start seeing methane go down, we can actually see the hydrogen rise because we're reducing the ability of hydrogen to get concentrated into methane. But typically Intestinal Methanogen Overgrowth in a patient that is constipated is very relevant and sometimes also you want to consider whether or not they may actually be having issues with candida or other fungal overgrowth because I see this often very much linked. So breath testing, you want to look at three hour breath tests, but really, only the first 90 to a hundred minutes. Let's talk a little bit about retesting. I'm a big fan of retesting, simply because I like to know whether or not the patient has really fully cleared SIBO. Sometimes symptoms are absolutely gone and retesting, is not absolutely necessary in those cases, but you want to know how long, if at all, a patient is relapsing. So, if you are getting treated for SIBO, you're feeling much better, then you don't retest, and at some point, the symptoms really creep back up, you want to know whether or not SIBO has actually returned, and if you're doing a breath test at that point, you may not know whether you had cleared it to begin with.

So for me, it's always important to retest, because that then tells me whether or not this treatment that I've used is successful, and so, I can use that treatment again in the future, in case of relapsing. So, that's one of the reasons I like to know whether or not the patient has really fully cleared SIBO. So that's the breath testing side, not much of an update other than perhaps the window of interpretation, and is I think more reasonable, really, at 90 to a hundred minutes than 120 minutes. And there's still a lot of practitioners that use the 120 minute mark, and may want to revise that to 90 to a hundred minutes.

Now, the IBS Smart, which is a trademark test from Dr. Pimentel's research, is a blood test to look for anti-vinculin antibodies, and anti-cytolethal distending Toxin B antibodies. Now, these two antibodies are present, if a patient has SIBO as a result of food poisoning. So the way it works is perhaps you had food poisoning a few years ago, and your gut never was the same, or slowly developed IBS-type symptoms after the food poisoning. What happened is your body created antibodies to the bacterial toxin of the food poisoning, and accidentally, because they're very similar looking to the vinculin, which is part of the migrating motor complex, you now have developed an antibody to the migrating motor complex, which is responsible for clearing the upper gut or the small intestine of bacterial overgrowth. So, if you're unable to do that, you have SIBO as a result of that, and that's really important to know, because these are the people that absolutely need prokinetics or medicines that restore the normal motility of the upper gut, in order to really remain SIBO-free.

So, that is a really useful test to have in your back pocket, if you're a practitioner, for those people who, like I said, have a history of food poisoning, or they may not remember it, that often is the case. If they are chronically relapsing, then you really want to consider this as a test to look for the cause of SIBO, rather than SIBO itself. So it's not a test for SIBO, really important to note that, you still need the breath test, but understanding the underlying cause of SIBO is really helpful.

So, I have created a little 10 minute PowerPoint presentation on when to use the IBS Smart. I'll put the link in the show notes, but generally speaking, if you have a patient with a food poisoning and the breath test is positive for hydrogen, and they may have either diarrhea or a mixed stool pattern, this is when the IBS Smart blood test is most indicated. For those patients who are methane positive and are more constipated, the IBS Smart tends to be less indicated. But follow the show note links, the PowerPoint is in the show notes, but you can also find it on, and just a 10 minute little PowerPoint on the underlying causes of SIBO and how to diagnose SIBO, and then how to use the IBS Smart.

I found it really useful, but it's limited to the presence of antibodies, and sometimes people, they're negative, and so, you have to keep looking for our other underlying causes, if you have a chronic relapser of SIBO. Sometimes it's mold. Mold can also be toxic to the gut. It's toxic to the myenteric plexus, which is part of the enteric nervous system of the digestive tract. And sometimes people have chronic stress and vagal dysfunction that can also lead to motility disorders. So, motility disorders are really often at the root of these relapsing conditions for SIBO.

Sometimes it's also obviously adhesions, we've covered that in many other podcasts, as a result of endometriosis or because of abdominal surgery. That can also happen that you have relapsing SIBO because there's just too much scar tissue, and a altered flow through the intestinal tract. So, but really, the IBS Smart is more for the motility disorder that stems from the damage to the migrating motor complex, very useful. And there are a few labs in the world, SIBO Test is one of them. We do distribute the test for the only lab in America that offers this. So there's only one in the world, and everybody that offers the test sends it back to this lab in America.

Now, hydrogen sulfide SIBO testing is still limited. There still is only one lab in America that offers this, and I find it mostly useful for those that have diarrhea-dominant SIBO, which is not as common anymore. So, there still is a lot of research I think that needs to be done for the hydrogen sulfide testing. It's not available in many places, so I'll just limit it to saying that it's useful, I find, only for those that are diarrhea-dominant in terms of SIBO. Now, hydrogen sulfide in the colon can cause constipation, but you can't really identify that very well with this hydrogen sulfide breath test, that you can potentially diagnose better with a stool test that I'll talk about in a moment.

But hydrogen sulfide SIBO has thus far been more of a clinical diagnosis where people are sensitive to sulfur, have more diarrhea and have more of a flatlining breath test, but again, there still are a lot of questions about hydrogen sulfide, and if you want to learn more about this, my previous podcast, a couple podcasts ago with Dr. Goldenberg, we talked about hydrogen sulfide testing and the sort of challenges with hydrogen sulfide.

Let's talk about SIFO, or small intestine fungal overgrowth, which is quite common  and quite often occurs in combination with SIBO. So people have fungal and bacterial overgrowth, really, really common and very difficult to diagnose because very often Candida evades detection. Even stool tests are not very helpful for being sure that Candida is absent or present. Sometimes I have somebody who has very clear SIFO, or at least fungal overgrowth symptoms, and that's always the challenge because Candida symptoms can be the same whether you have fungal overgrowth in the small intestine or in the large intestine. Fungal overgrowth can cause symptoms of fatigue and brain fog and bloating and constipation or diarrhea, rashes, itching, vaginal yeast infections, all sorts of symptoms can arise from fungal overgrowth. This is not necessarily just due to SIBO. Like I said, it can also be due to fungal overgrowth in the large intestine. This is what makes the testing inaccurate in terms of location.

So when you have somebody who's positive on a stool test for Candida, which is usually quite significant because Candida should really not be present in any stool sample necessarily and often means that immune system has been somewhat overrun. So if you find fungus on a stool test, typically that tends to be significant, but we can't say that's because of SIFO. So even an organic acid test, which is something I use a lot of to look at fungal markers, we don't know where the fungus is. In a way, it doesn't really matter where it is because the treatment for fungal overgrowth in the small intestine is the same as for fungal overgrowth in the large intestine. But I typically use more organic acid testing to understand the degree of fungal overgrowth.

Now, let's talk about stool testing. Stool testing, I'm a big fan of it, even though there is ... We're still learning a lot. We're still developing a lot. Or let's say, research is ongoing in terms of looking at microbiome imbalances. Functional digestive practitioners or functional GPs or medical doctors or naturopathic physicians, we use a lot of stool testing and have done so. I've used stool testing for my whole career, which is almost a quarter of a century now. I found it really useful, not just for looking at bacteria that are occurring or growing in the large intestine, but really to look at digestive markers as well.


Just to be clear, stool testing is not at all useful to help you diagnose SIBO. There's nothing on that test that will give you a clear definition of SIBO at all. It's mainly looking at stool bacteria that are prevalent in the large intestine. We know that from research that's really quite new in the last year or so that's come out. We know that the microbiome of the small intestine is completely different from the microbiome in the large intestine. I've done a podcast about this this year some time. I can't remember exactly when, but scroll through the episodes. It's a really interesting ... really illuminated for me that a stool test really only we understand what arrives in the colon. It's useful when you think about digestive function and how food is moving through the entire digestive tract and how it arrives in the colon. That is one of the reasons I often do a stool test, to understand whether or not there are enzyme deficiencies or hydrochloric acid deficiency potentially, what the inflammatory markers are, what the different phyla distributions are, the different groups of bacteria, if there is a prevalent overgrowth. It's so super useful for looking at all these different parameters of digestion.


So even though I may have a patient that has tested positive for SIBO, I may still do a stool test just to understand what's going on further down below. So really useful in any sort of IBS or functional digestive disorder realm.


Lastly, just a word on intestinal permeability or leaky gut, as it's known in more lay terms. But leaky gut is a real thing. It does happen and can cause a lot of systemic inflammation and food allergies and mood disorders as well. The reason I talk about it really is because SIBO can cause intestinal permeability or leaky gut because the gases are quite damaging. But also as a result of the body trying to clear the bacteria out, there is a mechanism where the gaps between the cells can open so that you can flush out bacteria. This is often why we see intestinal permeability after acute food poisoning just for a short period of time, because that's what the diarrhea is. It's this massive influx of fluid to try to flush these bacteria out.


But most of the time in my line of work, we see intestinal permeability as a result of long-standing infections or fungal overgrowth or a variety of other underlying reasons. It's a real issue because it can cause a lot of the systemic symptoms in people's gut disorders. So we see a lot of reactivity, a lot of reactivity, food reactions, and chemical reactions. A lot of people have developed food allergies as a result of intestinal permeability.


One of the issues with this is that we also see what we call translocation, bacterial translocation. Typically, we see this with gram negative bacteria and their inflammatory substances that are much more easily absorbed into the circulation and can cause or trigger inflammation. Intestinal permeability can easily be tested, whether that's a lactulose mannitol test. That's a oral ingestion of these two sugars. Yes, it's the same lactulose that we use for breath testing, but this is actually a urine test to look for the presence of these two and seeing if they have been absorbed. Lactulose is a very large molecule, and if it's present in the urine, we can deduce that there's been some intestinal damage for this to be ending up in the urine. That's a easy one there. Also, blood tests available that look at different markers, like zonulin and different immunoglobulins, etc. So- different immunoglobulins, et cetera.

So intestinal permeability, not everybody needs it, but in those that are very, very reactive, sometimes it's useful to understand the degree of intestinal permeability, and then obviously you have a variety of nutrients that are very helpful to help somebody overcome leaky gut or intestinal permeability. So those I think are really the majority of the tests that I frequently utilize in my practice, so breath testing for sure. Obviously I'm a SIBO doctor so I do a lot of breath testing and stool testing as well, and organic acid testing as well as intestinal permeability. Sometimes it's helpful to do food allergy testing for those that continue to be reactive to foods and sometimes it's surprising what shows up. There are a lot of, I'd say, inaccuracies often in labs where it's a tricky situation with food allergies to actually get a lab to be really, really accurate because we're looking for delayed type reactions.

So, I'm sorry, I didn't really explain that very well, but there's a lot of controversy, I'd say, around food allergy testing and really don't want to get into this too much. I don't actually do too much food allergy testing these days. I look more for food reactions like sulfur and salicylates, especially histamine, and that is the majority, I'd say, of my patient base. I'd say if somebody's reactive, they're more reactive to these food intolerances rather than an immunological reaction to different foods. And I used to do a lot more food allergy testing, but now I have limited that a little bit and it's probably because a lot of my patients are already on very restricted diets and so I prefer to do a food allergy test when people are actually eating more foods so that we can see if more foods are actually reactive.

So that's more of a testing overview of what might be useful. So think about if you've been on a SIBO treatment plan for a long time and either you're testing still positive or you are still having symptoms. Let's talk about that for a second because this is one of the reasons also for retesting. If you have been diagnosed with SIBO, you've been put on a treatment regimen, and here you are months later and you're still symptomatic, this is a great time to retest, to understand whether or not you still have SIBO or if the treatment was successful and you still have symptoms, because then you have to look at other reasons why you're still symptomatic. And that's when you might want to look at a stool test or some of these other tests that I've mentioned.

So hope this was helpful for you in your quest to understand why you still have gut symptoms and also understand that there are far more tests available, but these are, I'd say, the majority of the tests that I do very frequently in my practice. Thank you for listening and for your continued support for the SIBO Doctor, and really looking forward to a new season, season five, or is that six, but it's been five years. So we have a new year coming, new interviews, looking forward to telling you more about the interesting world of digestive health. I hope you have a very safe end to 2021 and I wish you and your family all the best for the new year.

Show notes

When to Test for IBS

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