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SIBO: Symptoms, Diagnosis and Treatment

SIBO: Symptoms, Diagnosis and Treatment, gut health, naturopath, gut naturopath, gut specialist

There’s a lot of discussion about SIBO (small intestinal bacterial overgrowth) online, but what is it exactly? I will cover SIBO: symptoms, diagnosis and treatment information for you in this blog.

SIBO occurs when there is an abnormal increase in certain bacterial populations in the small intestine (small bowel). It is completely normal for the small intestine to have some bacteria living there, however SIBO is associated with overgrowths of types of bacteria that are not usually found in the small bowel. The overgrowth of bacteria leads to fermentation of carbohydrates in the small intestine, rather than the large intestine, which causes some of the negative symptoms due to an increase in hydrogen gases.

There are also conditions such as SIMO (small intestinal methanogen overgrowth) and IMO (intestinal methanogen overgrowth), which are caused by overgrowths of certain archaea (different to bacteria J) that can occur separately or alongside SIBO and contribute to the symptom picture. SIMO is methane overgrowth in the small intestine, and IMO is methane overgrowth in both the small and large intestine. (1)

SIBO/SIMO/IMO can be a possible contributing factor to IBS, heartburn/reflux, diarrhoea, and in some people with long-term constipation. It can also be triggered after food poisoning or gastro, after antibiotics, when you are taking long-term PPIs (proton pump inhibitors) to help manage reflux, after long term use of opiate pain killers, by binge drinking alcohol (especially if you have had SIBO before) and if there is any kind of ongoing dysmotility in the gut (1-4).

Other medical conditions that may be associated with SIBO include coeliac disease, inflammatory bowel disease (IBD), fatty liver (NAFLD), liver cirrhosis, chronic pancreatitis, Parkinson’s disease, systemic sclerosis, mast cell activation syndrome (MCAS), depression, diabetes, fibromyalgia, lactose intolerance, and fructose intolerance. (1, 4)

Common symptoms of SIBO/SIMO/IMO

  • Bloating
  • Abdominal distension (when you can see that your belly is sticking out)
  • Abdominal discomfort and/or pain 
  • Flatulence
  • Frequent repetitive belching (often worse after meals)
  • Nausea
  • Diarrhoea
  • Constipation (especially in SIMO/IMO)
  • Slow transit time (especially in SIMO/IMO)
  • Malabsorption – fatty residue in the stool (steatorrhea); low iron stores or iron-deficiency anaemia, low B12/macrocytic anaemia
  • Food intolerance
  • Acne rosacea
  • Joint pain (arthralgia)
  • Neuropathy (usually due to low B12)
  • Brain fog

As you can see from the list above (4, 5), many of the symptoms listed above are also common in other gastrointestinal conditions, so you can’t simply assume that you have SIBO/SIMO/IMO – correct diagnosis is crucial for a better chance of treatment success. And treatment can take months, so you don’t want to waste money on specific supplements if you don’t actually have the condition.

How do I know if I have SIBO?

The only way to correctly diagnose SIBO/SIMO/IMO is via breath testing – you cannot accurately diagnose this condition via symptom picture, PCR stool analysis or even by using a microbiome map (even if I do love this kind of testing, and it’s often indicted for other reasons). You need to test BOTH hydrogen and methane breath gases or you may completely miss the possible diagnosis of SIMO/IMO. You’ll get the most accurate diagnosis by testing three sugars, not just one, because different bugs eat different sugars/substrates. The three sugars that will give you the best chance of identifying SIBO/SIMO/IMO are lactulose, fructose, and glucose. 

Essentially, after correct preparation, breath testing involves ingesting the substate and then blowing into a bag every 15-20 minutes (these lengths of interval are important for accuracy – 30 minutes is too long). You can only test one sugar at a time, and they can’t be done on the same day I’m afraid! You need to leave 3-7 days between testing each sugar for the best results. There are also home testing kits available from most testing companies, and newer technology like Food Marble, which I have been exploring with some of my patients who live in remote areas.

When the testing company analyses your data, they are measuring the level of gases exhaled in the breath at specified time points. If hydrogen is high enough to reach the diagnostic threshold at certain points in your results, you will be diagnosed with hydrogen SIBO. If methane is high enough, you will most likely be diagnosed with SIMO and/or IMO depending on where the methane gases are spiking. Note: it is also possible to have SIBO, SIMO and IMO concurrently. AND to make things more confusing, sometimes SIMO can disguise the presence of SIBO because those pesky little methane producing bugs can eat hydrogen as a food, so you don’t get any rise in hydrogen breath gases. Luckily you have well-trained practitioners like me who know how to read and interpret your test results accurately and ask you the right questions!

Schematic for carbohydrate breath testing (Saad & Chey 2007)

Treating SIBO/SIMO/IMO is not a “one size fits all” approach, as often treatments may need to be tweaked to a person’s particular presenting symptoms, health history and the balance of their gut microbiota (if that was tested). But in very basic terms, if you have high hydrogen breath gases, you need a hydrogen SIBO specific protocol. If methane is high, you need a methane specific protocol, and sometimes a special combination of the two of you have SIBO, SIMO and/or IMO (feeling dizzy with all the acronym use yet?). SIBO, particularly IMO, can be really stubborn, so you need to persist with the right kind of support for several months under practitioner guidance.

This is something that you cannot do by yourself at home, as you really do need the right blend of herbal medicine, probiotics, and prebiotics (down the track) to have a greater chance of success, and the internet is rife with “SIBO protocols” that are unlikely to be effective, and suggestions of using herbs that are far too strong and will also negatively impact your beneficial microbes creating all sorts of other issues. Not to mention that SIBO tends to reoccur if it is not treated properly, and with longer term plans implemented for correct management and resolution. 

Common SIBO Myths

And I’ll cover off some super common SIBO misunderstandings before I sign off….

1.    I’ve been told that you shouldn’t use probiotics when you have SIBO?

Yes, you can use probiotics, but they must be the correct probiotic strain/s for your particular presentation (see my blog on probiotics for more information on strain specific prescribing), introduced at the correct time, and used under the guidance of a SIBO/IMO savvy practitioner. They can be an effective helping hand if used correctly.

2.    I’ve been told that you shouldn’t use prebiotics when you have SIBO because it will feed the “bad” bugs?

Yes, you can use very specific prebiotics, and the list is small, but they must be tailored to your particular presentation under the guidance of a SIBO/IMO savvy practitioner, or they can sometimes exacerbate or give you unexpected symptoms. Using the right prebiotic at the right time, after proper investigations and assessment is extremely important if you don’t wish to experience adverse effects, as we need to be supporting the right bacteria to thrive.

3.    I was told that I need to kill off a lot of bad bugs in my gut to resolve SIBO?

Whilst you do need to control the growth of problematic bacteria to help resolve SIBO, you don’t necessarily need to use any product that kills bacteria/archaea indiscriminately in the gut. Depending on your current and past health history, it is often better to use herbs that work selectively, so they suppress less beneficial flora in the right places (like the small intestine), whilst still feeding your beneficial microbes, thus improving overall balance in the gut.

And you guessed it! You need to do this under the watchful eye of an appropriately trained practitioner. Someone (like me!) who has been trained by Dr Jason Hawrelak and is one of his Certified Healthy Gut Practitioners is ideal and who also may be SIBO Doctor Approved as well. I’m SIBO-Doctor approved, having completed all of Dr Nirala Jacobi’s SIBO specific training, and a registered clinician with Microba.

Please book in to see me if you need help managing possible SIBO, SIMO and/or IMO, so you can order the correct investigations and receive the most accurate and up to date advice. I’m happy to help 🙂


1.     Banaszak M, Górna I, Woźniak D, Przysławski J, Drzymała-Czyż S. Association between Gut Dysbiosis and the Occurrence of SIBO, LIBO, SIFO and IMO. Microorganisms. 2023 Feb 24;11(3):573. doi: 10.3390/microorganisms11030573. PMID: 36985147; PMCID: PMC10052891.

2.     Sroka N, Rydzewska-Rosołowska A, Kakareko K, Rosołowski M, Głowińska I, Hryszko T. Show Me What You Have Inside-The Complex Interplay between SIBO and Multiple Medical Conditions-A Systematic Review. Nutrients. 2022 Dec 24;15(1):90. 

3.     Tian L, Huang C, Fu W, Gao L, Mi N, Bai M, Ma H, Zhang C, Lu Y, Zhao J, Zhang X, Jiang N, Lin Y, Yue P, Yuan J, Meng W. Proton pump inhibitors may enhance the risk of digestive diseases by regulating intestinal microbiota. Front Pharmacol. 2023 Jul 17;14:1217306. doi: 10.3389/fphar.2023.1217306. PMID: 37529701; PMCID: PMC10387554.

4.     Bohm M, Siwiec RM, Wo JM. Diagnosis and management of small intestinal bacterial overgrowth. Nutr Clin Pract. 2013 Jun;28(3):289-99. doi: 10.1177/0884533613485882. Epub 2013 Apr 24. PMID: 23614961.

5.     Bures J, Cyrany J, Kohoutova D, Förstl M, Rejchrt S, Kvetina J, Vorisek V, Kopacova M. Small intestinal bacterial overgrowth syndrome. World J Gastroenterol. 2010 Jun 28;16(24):2978-90. doi: 10.3748/wjg.v16.i24.2978. PMID: 20572300; PMCID: PMC2890937.

6. Saad RJ, Chey WD. Breath tests for gastrointestinal disease: the real deal or just a lot of hot air? Gastroenterology. 2007 Dec;133(6):1763-6. doi: 10.1053/j.gastro.2007.10.059. PMID: 18054546. 

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