Comments about SIBO and IBS with Dr. Ben Weitz: Rational Wellness Podcast 316

Dr. Ben Weitz discusses SIBO and Irritable Bowel Syndrome with Dr. Ben Weitz.

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Podcast Highlights

0:32  I’m going to make some comments, pose some questions, and discuss some recent podcasts that we’ve done on SIBO and IBS. We had a discussion with Drs. Rahbar and Gurevich on SIBO and IBS: Discussion on SIBO and IBS with Dr. Sam Rahbar and Dr. Ilana Gurevich: Rational Wellness Podcast 298.  We also had a presentation by Dr. Mark Pimentel on the latest research that his group has recently published on SIBO and IBS:  SIBO: New Research Findings with Dr. Mark Pimentel: Rational Wellness Podcast 311.   I also recommend that you listen to the interview that Shivan Sarna and Dr. Allison Siebecker conducted with Dr. Ali Rezaie of Dr. Pimentel’s group:  Digestive Disease Week 2023 Research Update by Dr. Ali Rezaie (June 2023)   

3:42  Irritable bowel syndrome or IBS is the most common gastrointestinal disorder occurring in up to 20% of the US population.  It is a functional digestive disorder marked by the following symptoms: gas and bloating, stomach pain, diarrhea, constipation, or alternating diarrhea and constipation.  IBS is considered a functional disorder because if you do a scope or do a CAT scan, you won’t see any structural problems in the intestines.  By contrast, if you have Crohn’s or ulcerative colitis and you do a scope or a scan, you’ll likely see damage to the lining of the intestines, possibly bleeding, and erosions.  Because it’s a functional disorder, IBS was often considered to be a stress-induced disorder.  Dr. Pimentel has now proven that approximately 60% of cases of IBS are caused by Small Intestinal Bacteria Overgrowth or SIBO

5:35  The large intestine, aka, the colon, is a large and very elastic tube and it contains the trillions of bacteria, archea, and fungi that compose our microbiome. When these bacteria in the colon ferment and produce gas, this is not a problem. But the small intestine is a smaller tube and doesn’t stretch as much and doesn’t contain anywhere as much bacteria as the large intestine.  The small intestine is where most nutrients are absorbed from our food, so there need to be a smaller amount of bacteria lining its mucosa or this would interfere with this.  If you consume fermentable fiber and there is an overgrowth of bacteria in the small intestine, this can lead to gas and bloating, which can cause pain and a change in bowel habits.  Hydrogen sulfide and hydrogen gas are usually associated with diarrhea, while methane gas is usually associated with constipation. 


Dr. Ben Weitz is available for Functional Nutrition consultations specializing in Functional Gastrointestinal Disorders like IBS/SIBO and Reflux and also Cardiometabolic Risk Factors like elevated lipids, high blood sugar, and high blood pressure.  Dr. Weitz has also successfully helped many patients with managing their weight and improving their athletic performance, as well as sports chiropractic work by calling his Santa Monica office 310-395-3111. Dr. Weitz is also available for video or phone consultations.



Podcast Transcript

Dr. Weitz:            Hey, this is Dr. Ben Weitz, host of the Rational Wellness Podcast. I talk to the leading health and nutrition experts and researchers in the field to bring you the latest in cutting edge health information. Subscribe to the Rational Wellness Podcast for weekly updates and to learn more check out my website drweitz.com. Thanks for joining me, and let’s jump into the podcast.

                                Hello, Rational Wellness podcasters. Today I’m going to do a solo cast and I wanted to make some comments about some recent podcasts we’ve had about SIBO and IBS. We had an interview with Drs. Rahbar and Gurevich about SIBO and IBS, and we also had a presentation by Dr. Mark Pimentel on the latest research that he’s been conducting with his group on SIBO and IBS. And I wanted to mention to regular listeners of the Rational Wellness Podcast is that while most of the podcasts are typically me interviewing a guest or sometimes me just speaking, about once a month I organize this functional medicine discussion group meeting and we have a prominent speaker in the functional medicine space come in and sometimes we do a Q and A or they might do a presentation.  And so for those times when they do presentations like Dr. Pimentel did, you would probably benefit from going to my YouTube page so you could also see the slides. So all my podcasts are on Apple Podcasts, Spotify, wherever else you get podcasts, and then there’s also a video version on my Weitz Chiro YouTube page. So a lot of information has come through about small intestinal bacterial overgrowth and irritable bowel syndrome, and so I thought it might be important to give you some of my thoughts and comments and even some questions about some of this new data.

                                Also included in my thoughts are, having listened to an interview that Allison Siebecker and Shivan Sarna recently had with Dr. Ali Rezaie of Dr. Pimentel’s research group, Allison Siebecker also did a review of some recent papers from Dr. Pimentel. You can find out more about Shivan Sarna and Allison Siebecker’s information by information going to sibonfo.com, which is Allison Siebecker’s page, or going to the SIBO SOS website. So for anybody who’s listening who’s not really familiar with SIBO or IBS, let me define a few terms before we get started.  Admittedly, we’re going to get into some of the higher level science here, but if possible, in order to understand what we’re talking about today, if you go back, if you haven’t already, and listen to Rational Wellness Podcast episodes 298 and 311.

Irritable bowel syndrome or IBS is the most common gastrointestinal disorder occurring in up to 20% of the US population. Irritable bowel syndrome is a functional digestive disorder marked by the following symptoms, gas and bloating, stomach pain, diarrhea, constipation, or alternating diarrhea and constipation. Sometimes there’s urgency, sometimes there’s diarrhea, and there’s a whole bunch of other symptoms that sometimes are associated, and it’s considered a functional disorder because if you do a scope or do a CAT scan, you won’t see any structural problems in the intestines.  By contrast, if you have Crohn’s or ulcerative colitis and you do a scope or a scan, you’ll see damage to the lining of the intestines. You might see bleeding. You might see erosions. There’s structural things that are visible, but functional disorders, there’s nothing visible that you can see. And for many years, IBS was essentially considered a stress-related disorder. That is until Dr. Mark Pimentel discovered that many cases of IBS, approximately 60%, are actually caused by Small Intestinal Bacterial Overgrowth or SIBO, S-I-B-O. SIBO refers to an increase in the amount of bacteria growing in the small intestine.

                                The large intestine is a large and very elastic tube, and most of our microbiome is in the large intestine, also known as the colon. There, these trillions of bacteria ferment and produce gas, and this is not a problem. It doesn’t cause pain. It doesn’t cause gas and bloating because the colon can easily expand, but the small intestine is a smaller tube, it doesn’t stretch as much, and if there’s a bunch of gas produced there, then it’s liable to cause discomfort and/or gas and bloating as well as changes in bowel habits.  There’s supposed to be a relatively smaller amount of bacteria in the small intestine, and one of the reasons for that is because the small intestine is where most of the nutrients are absorbed from our food. And so if there was a large amount of bacteria lining the small intestine, it would be a lot more difficult for us to digest and break down and absorb the nutrients from our food.

And so if you consume fermentable fiber and there’s too many bacteria in the small intestine, those bacteria will digest that fiber and they’ll produce one of three gases. And those gases are hydrogen, hydrogen sulfide and/or methane gas.  Hydrogen sulfide gases are generally associated with diarrhea and when they are the cause of IBS this is generally referred to as IBS-D, for diarrhea, while methane gas is generally associated with constipation, and when this is the cause of IBS, it’s generally referred to as IBS-C, for constipation. So we refer to these three different forms of SIBO as hydrogen SIBO, hydrogen sulfide SIBO, and methane SIBO. So now we refer to methane SIBO as IMO or intestinal methanogen overgrowth to reflect the fact that it could be caused by methane producing organisms living in the large intestine as well as in the small intestine.

                                So now we’re going to get into some of the new data. So we now know that most cases of hydrogen SIBO are caused by the overgrowth of two particular bacteria, and that’s E. coli and Klebsiella. It’s very clear that when you have hydrogen SIBO the microbiome diversity goes down and you get these two bacteria predominant in the small intestine. And so one of the significant implications of this is we now know clearly that this is not the bacteria that grew up from the colon. When the concept of SIBO first came along, the thought was that the bacteria from the colon would grow up into the small intestine.

                                And one of the reasons we thought this is because the part of the small intestine closer to the colon, the duodenum, tends to have higher amounts of bacteria, but it’s clear now that we’re learning some of the particular bacteria that are causing SIBO, that in the case of hydrogen SIBO that’s not the case. And that probably also means that one of the thoughts of the things that increase your risk for SIBO were if you had a ileocecal valve that didn’t close properly or somehow the integrity of it was damaged or compromised in some way, that’s the valve that separates the small intestine from the large intestine.

                                Okay, so when it comes to hydrogen sulfide SIBO, we now know that the main components, the main bacteria that are responsible for that are Desulfovibrio and Fusobacterium. In methane, the main microbe is now known to be Methanobrevibacter smithii, and this is a methanogen, and it’s actually not a bacteria, it’s a microorganism. It’s similar to a bacteria but it’s not a bacteria. It’s actually known as a archaea, and is a very primitive microorganism. And the fact that it’s not a bacteria is probably at least one of the reasons why curing IMO or methane SIBO seems to be more difficult than a hydrogen form.

                                Now, the difficulty of curing IBS-C or methane SIBO or IMO has led to a number of alternative theories about what might be playing a role in such cases. And these alternative theories include that there may be co-infections of Lyme disease, there may be toxins like mycotoxins from mold, or there may be fungal overgrowth. At our functional medicine meeting with doctors Rahbar and Gurevich, they’re both practitioners who are treating patients regularly. Dr. Rahbar is a gastroenterologist, and Elana Gurevich is a naturopathic doctor who specializes in gastrointestinal disorders, and they both find that fungal overgrowth often seems to be playing a role, especially in cases of IMO. And they both also find that treating search patients with nystatin which is a prescription antifungal may be helpful.

                                One of the tricky parts about this whole concept is how can we test for fungal overgrowth? Fungal overgrowth, by the way, is sometimes known as SIFO or a small intestinal fungal overgrowth. Breath testing cannot pick up fungus, and stool testing is not all that accurate either. You can sometimes see candida on a stool test, but it’s not considered that sensitive for it. Urine testing has not been scientifically validated yet to the highest scientific standards as far as I know. Now, Dr. Gurevich noted that she will often task for candida antibodies by running a candida immune complex, an ELISA Antigen test for Candida IgG, IgA and IgM, and she’ll get this from a conventional lab like Quest or LabCorp.

                                Dr. Rahbar, I think for the most part, accepts that there’s a high likelihood that there may be fungal overgrowth and doesn’t necessarily test for it, though I think he sometimes does stool testing or urine testing or both. One of the interesting things that Dr. Gurevich said when she treats patients with fungal overgrowth is she may use nystatin or she may use nystatin for some of the treatment and the rest of the treatment she’ll use a series of herbs, which as a functional medicine practitioner is typically what I do when I treat patients with SIBO or SIFO. And one of the herbs she uses I thought was really interesting, she mentioned that she uses Gymnema sylvestre, which is an herb that I’ve often used for patients with blood sugar imbalances and/or diabetes. But Gymnema sylvestre has also been shown to prevent the yeast from budding and going into its hypha form when it’s harder to get rid of.

                                There’s a number of other herbal antifungals that she’ll use, including undecylenic acid, oregano oil, et cetera, et cetera. So we now know from Dr. Pimentel’s research with high likelihood, that most cases of hydrogen and hydrogen sulfide SIBO are caused by food poisoning. Now for a while this has been a theory with some evidence, but it appears to me that it is now pretty well proven. And the bacteria, campylobacter, shigella, salmonella or E. Coli that typically cause food poisoning, one thing they all have in common is they release a particular endotoxin, which is known as cytolethal distending toxin B.

                                And then when that endotoxin is picked up by the immune system, the immune system forms antibodies to CdtB, and then these antibodies cross-react with the structural protein in the intestinal wall known as vinculin, and this damages the cleansing waves. Now, what are the cleansing waves? We all know about the normal peristaltic waves when you eat. So as the food is going down you’re getting this rhythmic contraction of the intestinal muscles that helps to push the food down. But when you haven’t eaten for three or four hours, you get this peristaltic waves that are called the cleansing waves. And this is really done to keep a bunch of bacteria from growing in the small intestine.

                                So if those cleansing waves are damaged, that’s going to greatly increase the potential for overgrowth of bacteria in the small intestine. And so we now have pretty convincing evidence that perhaps 60% of cases of IBS are, particularly cases of hydrogen and hydrogen sulfide SIBO, are caused by autoimmunity. And we now have pretty convincing evidence that at least 60% of cases of IBS are definitively caused by SIBO, and that we can now rely on the lactulose breath test to diagnose most of these.

                                Now of course this doesn’t tell us much about the other 30 to 40% of cases of IBS that are not caused by SIBO and what is the cause of these? Might these be caused by SIFO or parasites or LIBO or dysbiosis or fruit sensitivities or something else? And that’s really a question. Dr. Pimentel noted that his data showed that a relatively small percentage of cases of SIBO also have SIBO, and he has that I think in the three to 5% range, while Dr. Rahbar and Gurevich find that SIFO appears to be more common. Now this may be partially because they are specialists who tend to see the worst of the worst patients.

                                Dr. Rahbar speculates that fungus facilitates the growth of the archaea, and this has been shown in studies where they’ve used yeast to help facilitate the growth of the archaea and the archaea responsible for the methane SIBO or IMO. Dr. Rahbar’s thought is that the fungus reduces oxygen from the small bowel resulting in an anaerobic environment and methanogens have to have an anaerobic environment. We know the colon is fairly anaerobic, meaning lack of oxygen, but the small intestine tends to have a certain amount of oxygen, but you really need to have an anaerobic environment for methanogens to flourish.

                                Once again, I mentioned we don’t really have a definitive test to diagnose SIFO, and this is really a problem. Now, I regularly on my patients with digestive disorders, will do a stool test and we’ll look for candida overgrowth. I have found that organic acids testing through urine is sometimes helpful to indicate fungal overgrowth as well. Now personally, since I treat SIBO patients mainly with herbs, many of the herbs that are antimicrobial are also antifungal. So I feel pretty good about that, and what that probably means is that there’s a number of cases where I am actually treating fungal overgrowth by treating the bacterial overgrowth because there’s overlap in the herbal effectiveness.

                                Okay. Now that methane SIBO is referred to as IMO to reflect that the methanogen overgrowth may occur in the colon as well as the small intestine, it would appear that breath testing may not be sufficient for a diagnosis since breath testing only measures the small intestine. However, what if we were to look beyond the 90-minute cutoff for the breath test, and since IMO occurs in the large intestine as well as the small intestine, and once again this is a question, should we look at doing the breath test for two hours and maybe even three hours and looking at what the methane level is beyond 90 minutes?

                                And then the question is, so we know what the cutoff is for methane in the small intestine, what should the cutoff be for methane in the large intestine? I’m assuming it would be higher, but that might be something for us to consider. And when you do the Genova SIBO breath test with lactulose, you can choose two hours or three hours. The trio test, you can only choose two hours, but you can choose to have the patients, instead of doing it every 10 minutes, they could do it every 15 minutes and you can stretch it out to three hours even though that’s not part of the instructions.

                                So the question is, would that be a good idea? And I don’t think we know, but I think that’s something that we should look into. And once again, it also certainly appears that stool testing now becomes a viable way to diagnose some cases of SIBO, specifically methane SIBO or IMO, because we can see Methanobrevibacter on a stool test, and both the GI map and the GIFX, two of the leading stool tests, both have those included. What about looking at the desulfovibrio as an indication of hydrogen sulfide SIBO, seeing desulfovibrio on a stool test? Do we know? Maybe it could be a factor.

                                What does what I’ve just said tell us about the treatment for IMO? So if IMO means that the methanogens are overgrown in colon as well as in a small bowel, then an antibiotic like rifaximin, which is believed to be not absorbed, that tends to act in the small intestine, might not be that effective for reducing the methane in the colon. So if you’re using antibiotics you might have to use systemic antibiotics. Unfortunately these are potentially going to damage your microbiome. What does this say about the use of herbs from methane? I don’t know if we really know which herbs are more effective in the small intestine versus the large intestine.

                                I mean, we do know that, for example, allicin is one of those herbs that seems to be particularly effective for methane SIBO. Methane leads to constipation. Now, why do you get constipation from methane? Is that because you’re not getting the motility of the GI tract? Is that because you’re not getting the rhythmic contractions in the intestines? No, because if the intestinal tract stops contracting, then the food will just go right through and you’ll have diarrhea. What happens in IMO, is that you get a spasm of the gut muscles, they hypercontract.

                                One thought I have is since we often use magnesium citrate to treat IMO, and that’s partially because magnesium citrate is a natural stool softener, but it’s also a natural muscle relaxer. And if what happens in IMO is that gut muscles are going into this hypercontraction, maybe magnesium is relaxing some of those muscles. All right, so those are the main thoughts I have about IBS and SIBO, and those are based on the talks we’ve already had as well as some of the data that Dr. Pimentel has been publishing or presenting at the recent GI conference.

                                So thank you very much, listeners, and I will see you next week. Thank you for making it all the way through this episode of the Rational Wellness Podcast. For those of you who enjoy listening to the Rational Wellness Podcast, I would certainly appreciate it if you could go to Apple Podcasts or Spotify and give us a five star ratings and review. That way more people will discover the Rational Wellness Podcast. And I wanted to let everybody know that I do have some openings for new patients so I can see you for a functional medicine consultation for specific health issues like gut problems, autoimmune diseases, cardiometabolic conditions, or for an executive health screen, and to help you promote longevity and take a deeper dive into some of those factors that can lead to chronic diseases along the way.

                                And that usually means we’re going to do some more detailed lab work, stool testing, sometimes urine testing, and we’re going to look at a lot more details to get a better picture of your overall health from a preventative functional medicine perspective. So if you’re interested, please call my Santa Monica Weitz Sports Chiropractic and Nutrition office at 310-395-3111, and we can set you up for a new consultation for functional medicine. I’ll talk to everybody next week.


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