SIBO: Yes, a diagnosis but also a symptom

When a patient is diagnosed with small intestinal bacterial overgrowth (SIBO), they often breathe a sigh of relief! Finally, the doctor has found what is wrong with me! In reality, the detective work has just begun.Digestive_Tract_1

SIBO is a condition in which microbes overgrow in the small intestine. We have many microbes living in our intestines but most reside in our colon (large intestine). Normally, the small intestinal environment should not be suitable for the survival of an overgrowth of these bugs.

The prevalence of SIBO in the general population is unknown. Research studies reveal anywhere from 0-20% of healthy individuals have SIBO. For those with irritable bowel syndrome, incidence of SIBO ranges widely from 4-64% or even higher depending on testing methods and testing criteria. This wide range in prevalence reveals the conundrum that SIBO presents; there is no gold standard to define or diagnose SIBO. Glucose and lactulose breath testing are most commonly used in the clinical setting but interpretation varies from institution to institution. 

Before I get started on my thoughts about SIBO, let me state clearly, that this is an area that has been researched, but much more work has to be done.  We need more studies to better understand the potential role of diet, probiotics, medications, food borne illness and their relationship with the onset and treatment of SIBO.  I am providing my musings based on research I have read in the medical literature, discussions with researchers, personal experience (I unfortunately have had SIBO), and professional experience as a registered dietitian– about 65% of my patients have been diagnosed with this condition. 

Although, it is possible that you may never determine how and why you developed SIBO, it is important to attempt to uncover the reason your developed an overgrowth of bacteria in your small intestine. SIBO has a good chance of re-occurring if you don’t find the root cause. Sometimes the cause is modifiable, to decrease rate of relapse –sometimes it is not. 

Here are my thoughts:

Step #1:  Attempt to uncover possible risk factors for the development of SIBO.  SIBO is a symptom per se, something changed the environment or function in the small intestine to allow microbes to overgrow. The medical team and the patient should work together to identify possible causes. The patient’s job is to provide an accurate account about the onset of symptoms to the doctor. The doctor assimilates this information along with testing and a physical exam to create the most viable potential causes. The dietitian tends to have a greater duration of time with the patient and is often a valuable player in helping piece the history together. This is just one reason why it is essential that medical professionals collaborate to provide the best care for the patient.  As a patient, encourage your health team to work collaboratively. 

Some potential causes of SIBO: Infection (such as food borne illness), untreated celiac disease, poor motility in the intestine linked with IBS or previous abdominal surgeries, GERD (gastro-esophageal reflux) treated with proton pump inhibitors (PPI) medication, chronic pancreatitis, hypothyroidism or diabetes, to name a few. What changed the small intestinal environment? What changed the small intestine motility?

Step #2: Is the potential cause treatable? If so, then treat.  For instance, if you can treat the new celiac patient with a nourishing gluten free diet and treat the SIBO with suitable antibiotics,  that patient might be all set. If you can lower the PPI dose or change from a PPI to an H2 Blocker, to treat heartburn or reflux, the small bowel pH (the amount of acid in the small bowel) might be less altered. Less acid in the small intestine may allow bacteria to overgrow. For example, the doctor might try try Pepcid (H2 blocker) versus Nexium (PPI) to manage the GERD symptoms. Perhaps this change in medication, will minimize the impact on the acid conditions in the small intestinal environment enough—so SIBO doesn’t relapse. Severe constipation or incomplete emptying of the colon, can impact small intestinal motility, a potential risk factor for SIBO too. If a SIBO patient presents with ongoing constipation—perhaps initiate a bowel regimen and check for pelvic floor dyssynergia. If a patient developed SIBO after a bout with food poisoning——(common food borne pathogens can lead to partial small bowel paralysis)—perhaps patients might benefit or low dose erythromycin at night (50 milligrams dose) to stimulate small bowel cleansing. Additionally, spacing meals out 3-4 hours vs. grazing will allow the migrating motor complex (MMC)–the housekeeper of the small intestine– to initiate a cleansing wave to cleanse the small bowel of food and bacteria. The MMC only occurs in the fasting state. 

I understand from a patient’s perspective that having numerous tests come back negative can  feel defeating, in a way. No one wants to be diagnosed with a life threatening illness, that is for sure. But, when illness, takes your quality of life away, it can be daunting.  When small intestinal bacterial overgrowth testing proves to be positive, patients often rejoice. Just remember, the detective work has just begun.

For more about SIBO, consider reading my long winded post here.  For dietitians in practice, you can purchase my patient ready SIBO handout ($10) to use with your patients, if you’d like.  The SIBO handout can be found here.

16 replies on “SIBO: Yes, a diagnosis but also a symptom

  • Michelle Peterson

    Kate- this is maybe the most helpful post I’ve read in a while. I was diagnosed SIBO years ago, but continue with constipation. I’m going to get in touch with my doctor, Dr. Adam Rinde, regarding your suggestions in #2!. I have never heard of Iberogast, or spacing meals for MMC, nor have tried erythromycin.
    My symptoms do seem to be focused in the small intestine- I even have physical pain in that area.


    • katescarlata

      Hi Michelle, glad to hear from you. I think the meal spacing is very essential. It has really helped me. If adding a bowel regimen such as added magnesium {discuss best choice for you w/ your doctor} doesn’t offer enough benefit–consider being evaluated for pelvic floor dysfunction. Definitely discuss openly with Dr. Rinde!

  • Sherrie

    Thank you so much for your wonderful blog! Your information is very helpful. Though my symptoms are not new, the SIBO diagnosis and low FODMAPs eating are new and, at times, overwhelming!

    My doctor has prescribed Neomycin and Xifaxan followed with SBO probiotics. There’s a lot of controversy regarding the use of SBO Probiotics. Do you recommend their use in your practice? Are they a short-term or long-term supplement? Is there something else that works well instead of this kind of probiotic?

    • katescarlata

      HI Sherrie,
      We just don’t know that much about the pros/cons of probiotic use in SIBO. It theory, after treatment with the antibiotics–and eradication of the small bowel bacterial overgrowth–they seem like a great way to replenish the gut with healthy microbes. BUT, theories don’t always play out they way we expect. I typically hold off on probiotics–until I know the SIBO is gone—then try to re-introduce them slowly. I choose probiotics based on the patient’s residual symptoms–choosing a probiotic that has evidence in the scientific literature to help the symptom that the patient needs to address.

  • Lois

    Hi Kate,
    When I had a sigmoidoscopy to try to find a reason for my symptoms … the colon was clean but with several diverticula. The gastroenterologist then suspected I had SIBO. In researching SIBO, I tend to agree. He suggested taking Flagyl, I chose to try the FODMAPS diet instead. From thinking about it, I’m suspecting the symptoms began to appear after I had what my internist thought was dysentery. I was put on 10 days of Ciprofloxacin. Is it a possibility that the dysentery/Cipro experience could be causing SIBO?

    Am pleased to have found your blog!
    Thanks, Lois

  • Mary Lou Ridler

    I always learn something from reading your posts, thank you so much. I have read in the past your comment about meal spacing, and I am going to really try and pay attention to that. I am home all day, and I eat all the time. Nothing “bad” or in volume, but there isn’t much rest time for my gut. Why not try what can be changed if it may help!
    Thanks, Mary lou

  • Suzanne Banfield

    Your posts are always so thoughtful and well-written, Kate – I really appreciate that. I was diagnosed with celiac disease 8 years ago and am scrupulous about my diet, but have had several bouts of SIBO over the last 3 years. My longest times between bouts (treated with Xifaxan and Neomycin) have been when I keep the FODMAP dose low, leave several hours between meals and leave at least 12 hours between dinner and breakfast. So far, I’ve gone up to 8 months between bouts, but I haven’t conquered it yet. Please keep informing us of everything you learn – you are one of the best and most reliable sources of information we have!

  • Christine

    Hi Kate,

    I’ve had quite a few relapses of SIBO and it seems like the combo of Rifaxmin and Neomycin while following a low FODMAP diet. I’m curious of your thoughts/if you’ve used the elemental diet or other herbal therapies to treat SIBO with your clients? As always, thanks for your help! Your posts are great 🙂


  • Tim

    Hi Kate,

    I’m feeling pretty desperate and could use dietary advice. My gi doc wants to put me on a 2 week course of Xifaxan for the ibs. I’ve read about SIBO, so far there’s not an apparent underlying cause. Tested negative for Celiac, negative for IBD, etc. Would you recommend trying the low FODMAP after the Xifaxan to keep symptoms better?

  • Divya

    I love your blog (especially your research updates and recipes – I’m going to try the quinoa crusted chicken and then see what happens when I use tofu!) that you don’t rely on supplements/substitutes that cost an arm and a leg, and make healthy FODMAP-friendly eating achievable for all of us. THANK YOU! I was diagnosed with SIBO after years of misery. What’s your take on IgE-mediated wheat/gluten problems and their co-existence with SIBO? Can one predispose the other? Or mask it? I tried challenging myself with a portion of wheat crepe last night, after no wheat (or FODMAP grains for almost a year. I was shocked to find that within an hour I began to feel like I had the flu, my body began to ache, had a sore throat and as for my tummy – this is a blog, I’ll leave it at that! I was “worried” about making it home and had to take antihistamine and I still feel flu-ey today but better. I thought that the reason I was doing so well without wheat, rye, barley etc (fructan foods) was purely FODMAP as I apparently tested -ve for transglutaminase (classic coeliac) and IgA deficiency. But after the debacle of last night and checking with my father (he’s a doctor, I’m a pharmacist), even he’s wondering if something else is going on. I know can’t give advice, but any reading tips or things to think in terms of challenging with other foods (hummus is next) about would be very helpful!

    • katescarlata

      Divya, I wonder if histamine intolerance might be part of your picture? Unlike systemic mastocytosis where an individual would have an abnormal amount of mast cells–individuals can also present with the inability to remove excess histamine from their body–this may be more of an episodic event due to alterations in gut bacteria, a diet rich in histamine and a genetic tendency to have less ability to degrade histamine. Somewhat of a perfect storm. I did a post on this topic here:

      • Divya

        Thank you for your help Kate, really appreciate your wisdom. I never thought of that but it’s possible, given that my father and I both have asthma and hayfever. I still feel a bit fluey today. Histamine contributors that I’ve kind of gone to town with of late (partially stress-motivated – I know, not clever) would be chocolate and sauerkraut. But I’ve eaten those before and never felt unwell. Except when I ate too much of the latter. Tofu is a trigger I know but definitely one of my FODMAP safe foods. No issues with shellfish, fish or eggs either. Perhaps I need to go back to the drawing board. Or accept that I gave wheat a shot and it didn’t work out. Bring on the rice!

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