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Understanding Small Intestinal Bacteria Overgrowth (SIBO)

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Hello, everyone! I’m Dr. Trish Murray – physician, best-selling author, and the Health Catalyst Speaker. Today I’d like to talk with you about SIBO. What the heck is SIBO? Well, it stands for small intestinal bacterial overgrowth.

Now, here’s an image of your GI tract. You know, you’re looking at a diagram of somebody’s abdomen. First of all, there are numerous organs in our abdomen. As you see in this person’s image, the walls of their body on the sides and their arms hanging down. But then you see up here in the top right their liver. But you also coming down through that area through the chest even and into the stomach is the esophagus.

So, when you eat something and you put it in your mouth and you chew it and you swallow it, it goes into your esophagus and then that travels down to get to your stomach. The stomach is where a lot of digestion starts to happen especially proteins get broken down by a very acidic environment. Your stomach is actually supposed to have a pH of 1.8. If you’re familiar with the pH scale that’s extremely acidic. Then from your stomach, food that’s been being broken down all along the way goes into the small intestines here. If you’re able to follow my cursor I’m kind of moving it and showing you that it goes into the small intestine, the upper small intestines.

Then you see that the small intestines are this worm-like squiggly tube that’s all bound up and twisted up in your abdomen. There’s like a tennis court surface area to your intestines. I mean it’s really long, but it’s all curled up and squished up in our abdomen. The food keeps moving through the small intestines, and it’s in the small intestines where we absorb nutrients. Once the food is broken down into its elementary units of proteins all the way down to amino acids and also carbohydrates down to the elemental sugars and of course fats down to the elemental lipids that get absorbed through the wall of the small intestine. So, the main job of the small intestine is for breakdown of foods, digestion, and absorption.

But then you come to the large intestine and the large intestine starts over here on the right side of your abdomen, comes up, and has this transverse colon that comes across the abdomen, and then down the left side of our large intestine or our abdomen to the rectum, which is the poop bag, if you will, and then out through the anus which would be the poop chute.

Now again, what is small intestinal bacterial overgrowth? Well, the majority of our microbiome that lives in our gut is supposed to be in our large intestine, meaning this big colon and predominantly even more in the left side of the colon. But the microbiome is going to be all throughout the colon, which is the large intestine. The bacteria are not supposed to be predominantly living, maybe some but way less. Like if there’s billions of bacteria, in your large intestine, colon, there should only be small amounts in especially your upper small intestine, meaning up near the stomach and the pancreas, for example. The pancreas isn’t even shown in this diagram and that’s an organ that puts out the digestive enzymes. It’s up over the stomach, so that’s probably maybe why they took it out of this diagram so you could see the stomach.

But that’s the concept is that small intestinal bacterial overgrowth is that bacteria from your microbiome that are supposed to be living in the environment of your large intestine have migrated up through all these little tubes too high up in the small intestine into an environment where they are not supposed to be living. If they then start digesting food for us up in our small intestine too high up, then we’re going to get the symptoms of small intestinal bacterial overgrowth.

So, let’s talk about what those are. The symptoms of SIBO can be quite a few different types of symptoms but, of course, all affecting the bowel and the in the gut. You could feel bloated or distended like you’re all distended and bloated and you may not be very hungry because you’re constantly feeling full even though you haven’t eaten in a while. You could have abdominal pain and cramping. You could have a lot of flatulence or gas. You can also have that gas going out the bottom end, but you could also have the gas coming out the upper end with belching and indigestion. You can have either diarrhea or constipation with SIBO. Now, you don’t necessarily have to have all of these symptoms either. You can have a collection of these symptoms.

The other thing that’s concerning or confusing about these symptoms is that other gastrointestinal disorders can present with the same symptoms. Somebody can have, of course, the most common irritable bowel syndrome with these types of symptoms, and someone could have inflammation of their bowel too, inflammatory bowel disease. Now, most people with definitive inflammatory bowel disease are going to also be having more pain maybe and also possibly passing blood with their stool especially if they’re in an exacerbation of inflammatory bowel disease. The bottom line is SIBO is not easy to diagnose or easy to definitively determine whether you have this versus another gastrointestinal problem because the symptoms overlap so much from one diagnosis to the next.

Now, what is the prevalence of SIBO? Well, it’s tough to determine a definitive prevalence because this is not an easy diagnosis in the first place, and it’s not the easiest thing to diagnose either. The prevalence appears to be more prevalent in women and also in older people.

Now, what are the possible causes of SIBO, and what are the predisposing conditions? There’s a long list. Let’s first look at the list on the left here. The first list I’m going to talk about are obviously things all related to the gastrointestinal system. Things like if you’ve had surgery that has removed or changed the structure of your gastrointestinal tube, your system, such as a gastric bypass or if you’ve had a colectomy, which means your large intestine has been completely removed or at least a portion of it has been removed. Then you’ll notice if your large intestine doesn’t exist then the bacteria have to live somewhere, so they’re going to be living in your small intestine so that’s a structural change due to surgery that has caused SIBO.

Another issue is medications. A very common one that’s out there, that people with chronic pain are on, would be opioids. People know that when you’re on opioids it gives you constipation and stops the motility of the food from moving through your gut properly and then being expelled and gotten rid of through the poop shoot. Opioids will cause dysmotility and slow down the movement of things through our gastrointestinal system which will allow bacteria to start migrating up through where they don’t belong.

You see, our intestines the small intestines and the large intestines should constantly have something called peristalsis or basically our nervous system is constantly giving messages to our bowels to be moving and squeezing and squishing, not squishing hard all the time, but the walls of the intestines should always, and there’s villi in there too, that should always be active and moving things downward through to the large bowel. If that isn’t happening, then that would be dysmotility or the motility is not happening properly or functioning and therefore bacteria could be migrating up in the wrong direction to live in the wrong places.

Another prescription medicine that gets people into a problem are called proton pump inhibitors. The Nexiums, you know the purple pill, and the omeprazole of the world. People with heartburn that are put on proton pump inhibitors for long, long periods of time…you’re blocking your stomach acid, and if you recall I said a little while ago that the pH of your stomach is supposed to be extremely acidic. A pH of 1.8. On the pH scale neutral is seven and everything below seven is more and more acidic, and your stomach is supposed to be 1.8. That’s an amazingly acidic environment. Then of course just south of the stomach and where the pancreatic enzymes come in are also going to be more acidic. Again, not an environment that is conducive to bacteria living there. If you’re on proton pump inhibitors for years on end and you’re not digesting food as properly as you should, then the environment in your upper intestine has become less acidic and more conducive to bacteria migrating up into that area and living and causing problems because they don’t belong there.

Pancreatitis could also put you at risk and also inflammatory bowel disease like Crohn’s or ulcerative colitis could be a predisposing condition for someone developing SIBO or small intestinal bacterial overgrowth. So, that’s the different things that would put you at… predisposing conditions or possible causes of SIBO that are related to your gut.

But look. There’s a whole other list, folks, of conditions that could be predisposing or possible causes of small intestinal bacterial overgrowth. The list includes rosacea. Rosacea, as you know, is an issue that usually is a skin issue on the face and a vascular issue on the face. One of the causes of rosacea can be hypochlorhydria. Hypochlorhydria means low stomach acid, so again you’ll notice these things do go hand in hand. Restless leg syndrome, diabetes, hypothyroidism, Parkinson’s disease, and coronary artery disease. If people have numerous of these or one of these conditions, they could be connected to them also developing SIBO. You’ll notice they do have to do with metabolic conditions, hormonal conditions, as well as nervous system conditions that would all affect that peristalsis, we talked about, and would also affect the function of again nervous system and hormonal system that would affect the motility within the gut.

Now, how do you diagnose SIBO? Well, there are two predominant ways to diagnose SIBO. The first one is considered the gold standard. That is this a small bowel culture, meaning you’re going to have to have an upper endoscopy where they put a tube down your throat through the esophagus down into the stomach and into the small bowel. Then they’re going to have to put some other tube down through that that’s a collection device to try and suck up some of the material in your upper small bowel to get the fluid and then be able to culture it and see what bacteria are living there. As you can see from my description this is, first of all, a very invasive test. You’re going to have to be knocked out for it, you know, for them to do an upper endoscopy. It’s got high cost. You have to go to a specialist to have it done, and it is fraught with contamination, meaning again they’ve got to get the tube down through your esophagus all the way into your small bowel. Then they’ve got to be able to run a collection device down through that and not get contaminated by the stomach fluids or other areas and just get a culture from the area they’re looking for. You can see, it’s fraught with possible contamination, but it is considered the gold standard test to diagnose SIBO. Get an actual sample of material from the area you’re trying to find out who lives there. That would be the gold standard.

The more common tests that you see people doing and even gastroenterologists doing is called a SIBO breath test. Now, the reason for a breath test is…why are we checking our breath it comes from our lungs? Well, what you do for this test is you would drink some sugar, some lactulose or some glucose, and then what happens is it’s going to move obviously down your esophagus to your stomach down into your small intestines and then transmit the carbohydrate, the glucose or the lactulose, is going to travel. There’s transit time down through your GI tract. Eventually it’s going to be ingested by your gastrointestinal microbes, the bacteria living in your gut. Typically, the microbes should be in your large intestine and when they, the microbes, break down or metabolize the carbohydrate, the glucose or lactulose, they give off hydrogen or methane gas. Once they’ve taken in the carbohydrate and eaten it, ingested it, they give off this these two types of gases. Then these gases get absorbed into our bloodstream, and then they pass in the bloodstream to our lungs and then of course we breathe out either the hydrogen or the methane gas or both. So, you’ll notice that’s how we then could connect our gut to breathing out these gases.

The key to diagnosing SIBO is how long is the typical time for us to ingest glucose or lactulose, let it run through our gut, meaning esophagus to stomach to small intestine to down into the colon and then have the time for the amount of gases to get to our lung to breathe it out. You can time it in a normal person that doesn’t have any SIBO. It would take longer for a normal person that doesn’t have SIBO, doesn’t have bacteria in their upper small intestine. It would take longer for this process to unfold. If someone has SIBO, then that glucose or lactulose is already going to start getting metabolized by bacteria in their upper intestine much sooner than normal, and therefore they’re going to start breathing off these gases, such as hydrogen or methane, much sooner than “normal.” So, if someone does the SIBO breath test and they breathe off hydrogen at greater than 20 parts per million within 90 minutes of doing this test… and you would breathe into something every half hour or so every 20 minutes or so over a two to two and a half hour time period, and they measure the level coming out of the breath at every measurement. Then you can track it. For methane, it’s greater than or equal to 10 parts per million within two hours, so that’s a little longer. Methane, if that’s positive in someone, that’s more consistent with someone with SIBO and constipation than the hydrogen is. So, these are the two diagnoses options for SIBO: small bowel culture or the SIBO breath test.

Now, let’s say you’ve been diagnosed with SIBO and you need to treat it. What are the treatment options? Well first of all in the traditional gastroenterology world many times people are prescribed an antibiotic and that’s about it. They might be told to do a low FODMAP diet which is a common diet that they’re told to implement, and they’re given a handout and you’re sent on your way. The antibiotic that is most commonly used is called rifaximin. The typical dose does range with different physicians but basically what I’ve read in studies is 1200 milligrams per day for about seven days. You can also play with the length of time; it could be more like ten days or fourteen days, but the idea is rifaximin 1200 milligrams a day for seven days. Now, rifaximin is typically the number one antibiotic used because when you take rifaximin it does not get absorbed into the body beyond staying in the tube of the GI tract. It just stays in the tube of the GI tract and kills the bacteria within that tract, not only the ones up in the upper intestine but also all over the place in the intestine and in the colon. The point is, you’re going to eradicate the bugs living in the wrong environment.

Now, rifaximin is not the only antibiotic that can be used, but again remember I said it’s unique in that it only affects the GI tract tube. It doesn’t get absorbed into your bloodstream, and it’s not systemic whereas other antibiotics like ciprofloxacin or metronidazole, which also could be commonly considered to be used for SIBO, are going to get absorbed into your full body into your full system. So, rifaximin is more commonly used.

The other thing you have to remember though about SIBO is that many times it is not resolved within one treatment with antibiotics. Many times, you have to repeat it because it comes back or the or the one course of antibiotics is not successful.

Now, another avenue that someone could go in order to get rid of the wrong bugs and where they’re living is called antimicrobial herbs. Instead of a prescription antibiotic, you could do a trial of numerous different…and I usually cycle them, meaning that for example grapefruit seed extract or oregano oil or caprylic acid. Caprylic acid comes from coconut and coconut is an antimicrobial type of chemical. I tend to ask someone to take a bottle, let’s say, of grapefruit seed extract a certain number of times a day for the entire bottle, let’s say a month. Then they could overlap the last week or so and start taking the next antimicrobial herb, let’s say oregano oil. Once the grapefruit seed extract is done and they continue the oregano oil and then towards the end, like a week or ten days before they finish the bottle of oregano oil, you could overlap the caprylic acid. Then continue the caprylic acid for another month. So, you notice you’re hitting the bugs with one antimicrobial herb and then another antimicrobial herb and then another antimicrobial herb. And there are other antimicrobial herbs that could be considered as well. You could keep doing this. This is another option for killing the bugs that don’t belong in certain areas, but do remember that it is going to have an effect on bugs not just in the upper small intestine but all through the colon as well.

Another portion of the treatment or another part of the treatment, you notice a multi-faceted approach to treating SIBO, is probiotics. Actually in 2017 there was a meta-analysis study done or review of eighteen different studies all on SIBO and using probiotics. The majority of them in this meta-analysis of all of these eighteen studies show that there was positive beneficial effect of taking probiotics in order to clear the negative bacteria or the bacteria from the upper intestines and help heal SIBO. Probiotics are a beneficial treatment modality also as part of the protocol for SIBO.

Now, we also can’t talk about any gastrointestinal disease or condition without talking about diet because, folks, whatever you feed your microbiome, whatever you feed your gut, whatever you feed yourself is going to determine your health. You can’t talk about really any disease process and particularly a gastrointestinal disease process without talking about diet.

Now, the most common diet that gastroenterologists, again I mentioned before, suggest people do when they if they are diagnosed with SIBO and also with irritable bowel syndrome which is very common symptoms to SIBO is low FODMAP diet. FODMAP is an acronym for fermenting oligosaccharides, disaccharides, monosaccharides, and polyols. These are all different kinds of saccharides, which are sugars, and they get fermented by bugs just like lactulose or glucose do, which are sugars and carbohydrates. If you lower your intake of these different types of sugars that will get fermented by bugs, then you would feed the bugs less food and therefore have less symptoms. So, you notice that could be very effective in decreasing symptoms and helping the bacteria move back where they belong.

Another diet that would be very important for people to consider would be to do a comprehensive elimination diet. This is a foundational functional medicine step because so many of us have food allergies or food sensitivities. Those two words mean different things, but food sensitivities are extremely common, but you may not know it. Meaning if you eat gluten every day and you just feel lousy every day, you really don’t know that the gluten is the trouble that’s causing the problem. You could be sensitive to more than one food. You could be sensitive to dairy. For example, myself. I am personally sensitive to dairy. I am sensitive to gluten. I am sensitive to caffeine, and I am sensitive to high FODMAP foods. That’s a lot of stuff, folks, but I live a wonderfully beneficial life and I find substitutes and I live as long as I follow the diet and the dietary restrictions for me. I’ve found substitutes that I can eat and be very fulfilled with my diet, but not have to live in pain and with bloating and all these symptoms we’ve been talking about.

To do a comprehensive elimination diet is imperative for someone to identify your food sensitivities. Now, I have an entire program on this called the Detox Plus Program on my website If you go there and you go to the shop, I have the Detox Plus Program which is a is a guidebook and it has five videos. It’ll teach you exactly what to do and how to do it in order to implement a comprehensive elimination diet.

Now, the last diet I want to talk about specific in relation to SIBO is called an elemental diet. The elemental diet is specific to someone that knows they have SIBO because what you’re going to do is you’re going to only sort of drink these pre-digested micro-nutrient foods that get absorbed. Meaning you’re sort of drinking this…it’s not very tasty, it’s pretty boring, and it’s a liquid I believe. It’s going to get absorbed in the proximal small bowel. For two weeks minimum, fourteen days minimum, and if you’re feeling somewhat better but not all the way better, you would go for a third week. You might be on this for twenty-one days. The elemental diet is the fact that you are drinking something that has only my already pre-digested micronutrients in it that are going to get immediately absorbed in your upper small intestines. You notice it’s not going to go all the way…the food that you ingest to give you nutrients is not going to go down into your lower small intestine and not going to get to your colon at all and therefore the bacteria are going to start dying because they’re starving. So, you’re basically starving your microbiome of food for anywhere for fourteen to twenty-one days. The ones that are in the upper intestines where they don’t belong are going to die off and they’re going to move back down into the large intestine. Again, an elemental diet is not easy. It’s not for the faint of heart, and a lot of people can’t handle it for very long, but it is a gold standard diet for SIBO.

The last thing I’ll talk about in treatment for SIBO are pro-kinetics, meaning remember I said that the walls of our intestines and the villi and then down into the large intestine are constantly moving things through. The nervous system should be constantly on-board moving things downward through our GI tract into the colon and then to be able to be eliminated? If something has caused your nervous system to not be functioning optimally and peristalsis and this motion and motility of the gut is not functioning optimally, then the bacteria is going to migrate up into the small intestines.

You can take things that would help with the movement and the motility, and these are called prokinetics. Now, there are some prescriptions that can be taken such as low dose erythromycin, which actually is an antibiotic. You can take a low dose of erythromycin which causes motility increase. You also could take low dose naltrexone, which is also a mild prokinetic. Again, you need a physician or a medical provider to prescribe these things.

Natural options for increasing motility with prokinetics would be ginger. Ginger has always been known to optimize gut health and decrease nausea. Herbal bitters like dandelion root or dandelion leaf or other things that are considered in the bitter family would increase motility. Then another recommendation or option is called iberogast which also improves motility. You notice from this there are multiple treatment modalities, so it’s a multifaceted approach.

Now, I have worked with people with irritable bowel syndrome and SIBO for years, and I have seen significant improvement for people if we approach the condition from a multi-faceted approach. I have created a protocol that I work with patients on on a regular basis. It consists of diet. Absolutely we usually would start with a comprehensive elimination diet maybe even with a low FODMAP overlap. I usually don’t implement an elemental diet unless we really, really have to go there because if you do a full protocol with multiple avenues of approach, many times you do not have to implement an elemental diet. It doesn’t mean we don’t have to go there at all. Some people do.

The next would be probiotics. These antimicrobial herbs that we’re going to rotate through also I meant didn’t mention earlier is digestive enzymes. Remember we said that if your upper GI tract is functioning optimally and it’s more acidic and you have the right enzymes there, then the bacteria are not going to want to live there. The environment is not favorable to them. If you take digestive enzymes, and sometimes digestive enzymes can have HCl, betaine HCl, in it which is hydrochloric acid. Sometimes we need to increase the stomach acid of our stomach in order to help optimize the environment of the stomach as well as the upper intestines.

Another portion of the protocol I typically use with folks would consist of glutamine. Some form of glutamine in a supplement in order to heal the intestinal mucosal lining as well as foods like bone broth.

Again, I have used a GI protocol with my clients, and it’s been extremely successful over the years in order to treat SIBO, small intestinal bacterial overgrowth, from a multi-faceted approach.

If you want to learn more, you could always go to my website I also offer a free 30-minute consult so if you go to my website, you’ll see right at the beginning I think it says, “Are you ready to feel better?” If you click that, you will have the option to sign up for a possible free 30-minute discussion with me. So, I hope this has helped. Small intestinal bacterial overgrowth, I think, is more common than we all realize. It is not the easiest thing to diagnose, but it is diagnosable, and it is treatable. So, I hope this has helped. I’ll see you on the next episode of Discover Health Podcast.


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