How SIBO (Small Intestinal Bacterial Overgrowth) Wreaks Havoc on Your Digestive System

by | Jan 15, 2019 | Blog, Western Medicine | 0 comments

This article is based on the interview Jennifer Crisp, RN, of A Bridge To Wholeness had with Marissa Southards on A Bridge To Wholeness podcast. You can listen to the interview on iTunes, Stitcher, and on our website.

Jennifer Crisp: Today, I am very excited and honored to introduce Doctor Kevin Passero. A licensed Naturopathic Physician with a practice in Annapolis, Maryland, as well as Washington DC. Doctor Passero received his Naturopathic Medical Degree at the National College of Naturopathic Medicine in Portland, Oregon. He’s also a former President of the Maryland Naturopathic Doctor’s Association and is an active member of the American Association of Naturopathic Physicians. Welcome, Doctor Passero.

Kevin Passero: Thanks, Jen. Thanks for having me today.

Jennifer Crisp: Well, I’m really excited that you’re here today. As a Naturopathic Physician, I know you deal with many, many issue … many health issues with your patients. There’s so many different topics that we could discuss today, but I would really like to talk about SIBO. What it is and maybe what we can learn about it and help people with. So, what is SIBO and why is it so important to have it treated?

Kevin Passero: So it’s a really common term that people are now coming across. It stands for small intestinal bacterial overgrowth. What it refers to is the situation where bacteria that typically live in our large intestine have translocated into the small intestine. We know … everybody is familiar with, now, the microbiome and this idea that our intestines are filled with all these billions of microorganisms that are super important for our immune system, and nutrient absorption, and our overall health.

What people really don’t realize is that most of those bacterial populations are supposed to be in the large intestine. The small intestine, where most digestion and nutrient absorption occurs, does have bacteria. But, not nearly the amount that’s in the large intestine. What happens in small intestinal bacterial overgrowth is just what the name implies. For some reason or another, and there are various reasons that we may discuss later, the bacterial count in the small intestine has exploded out of control.

Those bacterial growth create a secondary gasses that then result in a lot of problems in the small intestine. Not just symptoms, and we’ll talk about those later, but also other functional issues. Like, reduced nutrient absorption and other problems.

Jennifer Crisp: So why is it even important to have it treated? Won’t it just go away by itself?

Kevin Passero: No, most people want to treat it because they’re miserable, first of all, symptomatically. No, it typically won’t go away by itself. Just like when an infection sets in in any other part of the body, sometimes we need things to assist getting that infection under control. Whether that be antibiotic therapy in a more traditional route, or if applicable, herbal or botanical therapy, or nutrient therapy if we’re using a wholistic model.

So it does often take some degree of therapy to get it under control. Again, most people are very symptomatic with it. So they feel so much better on a day to day basis, in regards to their digestion. Now, in addition, because it affects nutrient absorption in many people, some people experience pretty severe side effects. They can have severe weight loss. They can have problems with their skin, their nail, their hair. Important nutrient deficiencies, like B12 deficiency, which can affect the neurological system. So some of these deficiencies can be manifested with quite dramatic symptoms. So that’s why you want to get it treated.

Jennifer Crisp: So normally, what brings a patient in to see you if they’re having that type of digestive issue? Like, what do they present with?

Kevin Passero: Yeah, well, I mean one thing that people can do is if they email my office at greenhealinginc, I-N-C, at, we can send you … I took about, I don’t know, two weeks and gosh knows how many hours to put together a SIBO questionnaire which is based on a point system and it’s based on a bunch of symptoms, risk factors, preexisting conditions, medication use. As you fill it out, you get a score at the end. Then, that score will sort of give you an idea whether or not you’re very unlikely or very likely to be really dealing with SIBO. Which then usually means, if you’re a high score, that we want to do some testing, which I think we’ll talk about in a few minutes, Jen.

But the thing that brings people in … Most people don’t come in saying, “Doctor, I think I have SIBO.” Although, many more people are because there’s a lot more out there on the internet about it. It sort of replaced the popularity of leaky gut. These days, as far as the articles and all the chatter you hear on the health websites and newsletters that people get. Most people are just experiencing some degree of symptoms. Probably, one of the most common one that I can almost guarantee it might be related to SIBO is just a lot of chronic bloating. Particularly after meals, people feel very bloated, they feel very full. They’ll say, “I feel like I’m five months pregnant after I eat a meal.” They’re just uncomfortable. They may be gassy through either end.

There’s a lot of other symptoms that can be traced to SIBO. I’ve done a lot of work with acid reflux. Acid reflux, often times, can be caused by a small intestinal bacterial overgrowth. Many cases of just what’s considered to be irritable bowl syndrome. So that could be chronic diarrhea, it could be chronic constipation. It could be alternating constipation and diarrhea. Stomach cramps, digestive issues, just generally feeling unwell with digestion, that’s often times very much related to SIBO.

So people come in with just a host of issues. “Doctor, I don’t know what to eat. I feel like I’m sensitive to everything. I eat food and I get bloated, I don’t know what’s going on. I can’t get out of the bathroom. I’m always having these GI problems, I’ve had them for years. I’ve got reflux and my doctor prescribed me this drug. I don’t want to take it.” I may hear any number of those stories. Then usually, one of the things that I’ll do in the differential diagnosis is look into SIBO as a possible contributing cause. See if it’s present via the relatively accurate mechanisms of testing that we have.

If it is there, then we go ahead and move forward with treatment. I rarely treat just based on symptoms. But those are the common things that I hear. Again, doing the questionnaire will help you get an idea for the symptoms that are most associated with SIBO.

Jennifer Crisp: So what type of testing do you use? I know you just said you don’t go just by symptoms. But is there a particular test that people can take?

Kevin Passero: Yeah, so the gold standard test right now is the … it’s a breath test, lactulose breath test. There’s a couple other variations of different sugars people can use. But it entails swallowing a solution of liquid that has a type of sugar in it. That sugar is metabolized by the bacteria in the small intestine that generally shouldn’t be there. If there’s enough of them not there, they create typically either hydrogen or methane gas.

Those hydrogen and methane gases are then given off in the lungs. So they drink a solution, then every 20 minutes they collect a breath sample. It’s about 14, 13, or 15 breath samples, I can’t remember how many, in the course of the collection. They collect a sample every 20 minutes. Then, they send that air sample that is collected in this bag and the lab analyzes it for the levels of methane and hydrogen. Based on what we find, that lets us know whether or not there is a small intestinal bacterial overgrowth issue.

The test is considered to be quite accurate. No test, at least this test, is not 100 percent accurate. But it is quite good at flushing out these issues. We don’t want to be putting people into sedation and putting tubes down their throats if we can just do this simple at home breath test. That’s usually covered by insurance, and doesn’t take very long to do, and is very minimally invasive, and quite accurate.

So that is, at this current time, the gold benchmark for testing for SIBO. You need to make sure that test contains both samples from methane and hydrogen. Some of the labs out there, maybe only do one of the gasses. It’s very important to make sure that the test covers both gasses.

Jennifer Crisp: Oh, that’s really good to know. Okay, that’s actually very important. You’re saying that most of the time, it is covered by insurance?

Kevin Passero: Yeah. Most of the time, this is an insurance coverage. I actually just had a patient in right before we did this interview that I’m working with SIBO. She was happy to report to me that Medicare is now covering it.

Jennifer Crisp: Oh, great. Oh, wow. That’s a … that is absolutely fabulous. Okay, so you have somebody who comes in, they get … actually, they get the test back, they get the diagnosis. Then, what’s the next step? What do you do? Do they have to change their diet? Do they add things to their diet? Take things out? What do they do?

Kevin Passero: Yeah, so there’s a couple different methodologies to approach. There are some foods that tend to make SIBO worse. This is what’s referred to as the FODMAP Diet. The FODMAP, each letter in the word FODMAP, F-O-D-M-A-P, you can look it up, stands for a different type of sugar. These different type of sugars exist in different kinds of foods. These bacteria preferentially like those types of sugars.

So many people that are administering SIBO treatments will recommend that people go on a low FODMAP diet, is what it’s called. Meaning that they’re limiting these foods that contain these types of sugars. Fructose saccharides, alegrio saccharides, disaccharides, monosaccharides, so that’s sort of what the FODM and then it goes on to the other ones. So it’s random what foods they’re in. Some vegetables are permissible, some aren’t. One of the highest FODMAPs foods is, let’s say, onion is a very high FODMAP food. So is garlic.

So sometimes people come in and just say, “You know, onions just … oh my gosh, I bloat like crazy.” Somebody says that and you know that they’ve got, most likely, a small intestinal bacterial overgrowth issue. Now, with that said, in early stages … early periods of my practice of treating SIBO, I was very strict with patients about needing to do a FODMAP diet. Then, there was a lot of debate that you really weren’t going to get somebody well unless they followed a very strict FODMAP diet.

It’s a debatable … it’s debated in the community. People feel that if you can tolerate a food that’s on the FODMAP list, you can go ahead and eat it. Some people feel that you shouldn’t restrict FODMAPs because if you do, you sort of suppress the bacterial growth and then your antimicrobial therapies are not quite as effective. My approach is that we want to go through with each patient and look at the FODMAP foods. We want to go through a list of those foods with somebody and say, “Is there any one of these foods that you know you react to?” If somebody is eating a food that really makes their condition worse, I don’t want them eating it. Do they have to pick through every single thing that they eat?

Jennifer Crisp: It’s very strict, isn’t it?

Kevin Passero: It’s very strict. It’s very … it’s just odd. Like, the kinds of fruits you can have and the kind you can’t. Or the kind of grains you can and the kind of grains you can’t. The kind of vegetables you can and the kind you can’t. The kind of sugars you can and the kind you can’t. So it just gets very difficult eating out, traveling, like a normal day to day lifestyle trying to figure it out. So we try and identify the highest FODMAP foods. We try and ascertain whether or not we think somebody is reacting to them. If they seem to be, we really want to lower it down because they’re gonna have trouble getting better. But really, the primary approach to treatment is antimicrobials. So this is sort of the going in old cowboy, guns blazing type of approach. Where you’ve got a bunch of bad guys, these bacteria shouldn’t be here, and your goal is to go in and kill them. Then, there are differing approaches to how to use antimicrobials based on, let’s say, what might happen in a conventional gastroenterology practice. What might happen, per se, sitting down in a Naturopathic doctor, like my office.

Jennifer Crisp: So can you explain that? I do know that there are a couple of different approaches to this. I think it’s important for people to understand what the differences are and why it’s important to be able to make that choice on your own.

Kevin Passero: So basically, we’re gonna be selecting some type of antimicrobial. So in the conventional world, that’s gonna be what people are mostly used to, an antibiotic, basically. From the natural pharmacy, we have natural antibiotics. Antibiotic just stands for, anti-life. So we have, in the natural pharmacy, what we call antimicrobials or antibiotics that are not a prescription antibiotic, like a penicillin, or erythromycin, or whatever it might be. Now, there is one type of antibiotic that is considered to be quite effective in SIBO, it’s called Xifaxan.

It’s an interesting antibiotic because it does not get absorbed past the gastrointestinal tract. So it has very limited systemic problems and people tolerate it really well. It can work very well, in my experience, the course is fairly short, usually seven to ten to fourteen days. It tends to not always be covered by insurance and it tends, if it’s not, it’s very expensive. This drug used to be like almost 800 to a thousand dollars for a course of Xifaxan if your insurance didn’t cover it.

The other issue with it, was that I found many patients would take a seven to ten day course, feel much better, but then have the symptoms slowly creep back in. [inaudible 00:14:28], it wasn’t a long enough treatment cycle. Some doctors use other combinations of antibiotics. Like I said, erythromycin. There are different antibiotic combinations that doctors will use to treat SIBO.

The problem I have with those is that while they may deal with the intestinal imbalance in the small intestine, we know that these antibiotics create negative large scale changes of the beneficial bacteria even in the large intestine.

So you’re kind of trading one thing for another. The courses can only be so long. I mean, how long can you put somebody on it? Seven days, ten days, fourteen days at the longest. Then, you start extending past that and even doctors recognize that you’re creating some potential side effects that aren’t really worth the benefit. The reality is that the SIBO issue in most cases is very stubborn and somewhat difficult to treat. So if I’m using natural antimicrobials, which I use in my office, that are not prescription based. That are based on herbs, essential oils, botanical extracts, they are very effective. You can give them safely for long periods of time.

Do you create some potential risks with killing off some of the good bacteria in the large intestine? Yes you do, but basically very rarely do you ever see patients have symptoms. The negative side effects like C diff, or diarrhea, or any kind of stuff that people … yeast infections that people experience on conventional antibiotics when using the natural microbials, they’re tolerated very, very well.

Now, the doctor who originally discovered SIBO, or really popularized it, Doctor Gerard Mullins from John’s Hopkins University. A Gastroenterologist there. He did a multi-phased clinical trial on patients with SIBO comparing the effectiveness of antibiotics and two different herbal protocols. At the end of his multi-centered trial, it was determined that all three treatment recommendations, there were two different herbal protocols and the antibiotic protocol, all worked equally in resolving SIBO.

There’s no critical evidence to show that there’s any more efficacy in using antibiotics. That’s an important thing for people to note. Because many people, if they’re very sick, they just say, “Give me the strongest thing that you have, doctor.” Of course, they think that because something is a prescription, that it’s stronger. But the reality is, Jen, you may know this first hand, the most difficult infections to treat, we’re finding now are actually some of the most responsive to things in the natural pharmacy.

Jennifer Crisp: Yes, yes. I mean, with that’s … I think that, as everybody knows, my goal with approach to wholeness, is to bring these alternative and conventional medicine practitioners together so you can have these discussions. I mean, I’m really glad that the doctor at John’s Hopkins actually really bothered to even do that trial and that study. That’s a great step. So okay, so what happens when a patient gets treated with the antimicrobial protocol that you design? What kind of results do they see? What happens as they move through the process?

Kevin Passero: Yeah, well typically, what happens is most people … it’s very rare that somebody … that we end up doing a SIBO test and getting a diagnosis where somebody isn’t symptomatic to some degree. So very, very predictably, typically within the first, I would say, 14 days of treatment. People are noticing significant changes in their symptomatology.

So if it was chronic bloating, they’re not feeling as bloated anymore. If they were having acid reflux, their reflux is calming down. If they were having IBS symptoms, those are calming down. Symptomatically, whatever they were experiencing in their GI system is starting to improve quite rapidly. Then usually, over the course of treatment, and most of my treatment protocols are at minimum, six weeks. I find it’s just a stubborn condition to treat.

As those weeks progress, typically, people experience continued improvements where they just start to feel better and better every week. By the end of the six weeks, they’re really having either complete resolution or usually somewhere between like a 70 to 90 percent improvement in their symptoms, if they’re not completely resolved.

Jennifer Crisp: What do you do after that six to eight weeks? Do they get retested?

Kevin Passero: Right. So then what you do after this first six week protocol, we end treatment. Then, we wait two weeks to allow the system to sort of repopulate to whatever it’s new baseline is going to be. Then, we repeat the breath test and see where we’ve gotten. I will tell you that in at least 60 to 70 percent of my patients, there is another round of treatment typically necessary. That may be very obviously, meaning, that somebody may still have some symptoms.

They say I felt really good on the protocol, but in the two weeks that I’ve been off of it, I don’t feel as good. I’m not as bad as I was before I did it, but I definitely felt better on the protocol. We clearly know that there needs to be re-treatment. Some patients, they still have complete resolution of their symptoms, but their test is still abnormal. Then, we have to have a discussion of, does this make sense? Should we just do another round just to really make sure that this is taken care of?

Most patients, after going through the six weeks noticing how much better they feel, even if they’re completely asymptomatic, are very willing to repeat another round of treatment. To just ensure that they’ve really gotten everything under control and they won’t have to deal with the issue again.

Jennifer Crisp: Okay. Then, how often did they have to take the antimicrobials? Is it once a day, twice a day? What is it?

Kevin Passero: My typical protocol is a combination of anywhere from two to four formulas, depending on the case and what’s going on. You take a couple capsules of each twice a day. So the usual capsule burden is about six capsules twice a day, so that’s two of three different formulas. Usually taken after you eat on a full stomach, because some of them have a lot of essential oil concentrations which can just be a little tough on the stomach if you take it on an empty stomach. So fairly straight forward, fairly simple. They’re not terribly complex treatment protocols.

Jennifer Crisp: Right, okay. Okay, good. Well, I’m really glad we had an opportunity speak about this. We only have a little bit of time left. But how can people find out more about the questionnaire that you have? Do have a newsletter or website that people can look at? How can they get in touch with you. I know you’re in the Annapolis and Washington DC area, but I believe you have patients nationwide, if I’m not mistaken.

Kevin Passero: Yeah, we have many people that hear about my work on the internet, or referred by a friend or a family member and they live out of state. We do do a fair amount of work with people that don’t live locally. So if you think you have an issue, you can call the office, we can see what’s going on with your case and decide if you would be a candidate for having any kind of remote treatment or whatever it is that we can do for you. If you want to learn more about the practice, the website is www.greenhealingnow, all one word, dot com. I don’t have any particular articles or blogs up on the website right now related to SIBO.

Jennifer Crisp: You have quite a bit, though, related to many, many, many conditions.

Kevin Passero: Yeah, I mean, we have a pretty extensive blog archive. Many people really give us a lot of positive feedback about the information.

Jennifer Crisp: It’s a great website, very good website.

Kevin Passero: There’s a link to the radio show that I do. Then, if you want the questionnaire, that’s something that I developed about three months ago as part of a project. The project didn’t end up going where I wanted it to go, but I spent a ton of effort and I just haven’t really put it up on the website. This is the first time I’m really offering it to anybody in the public, outside of myself and my staff, who helped me review it.

If you want access to it, I’m happy to send it out to your listeners, Jen. Just have them email the office email at and ask to be signed up for our newsletter. If you’re willing to get on our newsletter, which I send out maybe one a month, we’re happy to send you a free copy of the SIBO questionnaire that you can do at home and get an idea of whether or not you think this may be an issue you’re dealing with.

Jennifer Crisp: I think that would be really, really fabulous. Because I know that I speak to a lot of people who have digestive issues and I’m just like, “Get it checked out. Don’t sit back and wait, and become so miserable that you can’t function.” So I just want to thank you so much for your time. This is a really great amount of information in a short amount of time. But I have a feeling that … we are learning more and more about the microbiome, and the gut, and digestion. What is maybe one thing you can leave us with that … I know you’re really adamant about, as far as eating goes?

Kevin Passero: Well, I mean, I guess there’s a couple of different directions. Do you want me to leave you with one thing about SIBO? Or leave you with one general thing about health?

Jennifer Crisp: How about one general thing about health.

Kevin Passero: About health, okay. So in the 15 years of doing the work that I have been doing, I have never seen as miraculous and profound changes in people’s health in short periods of time, than I’ve seen when I’ve implemented intense nutritional programs for people. What that has taught me and what I’m distilling it down to, is that what you eat is the most important factor in your health. That is clearly what I have learned, it’s what I was taught in school.

I strayed away from it because it’s difficult to create a structure in the clinical setting where you can truly make people change their diet or give them the support they need to change their diet and have come full circle in the last three to four years. As I’ve incorporated nutritionists into the work that I do to dovetail right into cases. I have seen things happen in people’s bodies that no doctor would ever think was possible, including myself.

It is a true testament to your bodies innate ability to heal. What I tell patients at every single second of every single day, you’re cells are trying to express optimal health. It is just trying to remove the obstacles that are in the way of allowing your body to do that. For the majority of people in modern society the food that their eating is the biggest obstacle to allowing to happen.

Jennifer Crisp: It is. We’re gonna have to have you back and just talk about that topic. About how to make those changes that will benefit you. That’s another whole thing. Again, there’s so much information out there and people get so confused. Now we’ve got the big Keto thing going, and that, and that. People are just like, “Oh, my God.” So. I just want to thank you again for talking about small intestinal bacterial overgrowth. Again, if you want to get hold of that questionnaire, they can reach you at Also, sign up for that newsletter. So thank you very much. Thank you today for tuning in and listening to our Podcast. Please make sure you share it. If you enjoyed it, please take some time to review it. We will see you on the next show, thank you.

To listen to this interview on the podcast, find us on iTunes or Stitcher. You can also listen to it on our website by clicking here.

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