What you need to know about SIBO – Part 1

Rebecca Coomes The Healthy Gut Blog Post What You Need To Know About Sibo I Blog 1

What you need to know about SIBO

Have you heard of SIBO and wondered what it is? Maybe you’re experiencing digestive problems but haven’t investigated Small Intestinal Bacterial Overgrowth yet? In this 2 part article, we’re going to shed some light on this often overlooked condition.

SIBO is the leading underlying cause of Irritable Bowel Syndrome (IBS), yet is still largely unknown by the medical community and general public alike. We’ll delve into what it is, what symptoms you can experience with it, how you get it, and what associated conditions are known to be more likely to experience SIBO, how to find a practitioner and how to test for SIBO.

Rebecca Coomes The Healthy Gut Blog Post What You Need To Know About Sibo I Blog 1

What is SIBO?

Once you’ve heard of it your next question is undoubtedly going to be, ‘what is SIBO?’. SIBO is an overgrowth of normal bacteria in the small intestine. This bacteria normally live elsewhere in the gastrointestinal (GI) tract, but have overgrown in an area they’re not supposed to be in such large numbers, causing havoc. It is not pathogenic bacteria (meaning, it is not an infection), but instead is normal bacteria that has set up home in the wrong location: the small intestine.

What are the symptoms of SIBO? 

Do you regularly feel bloated, have constipation, diarrhoea (or both), experience abdominal pain, have food intolerances or experience weight gain/loss? If so, you may have SIBO.  

For many people, their SIBO symptoms can creep up on them. Over a period of time, your digestion can become more problematic and you may start to notice that certain foods make you feel unwell. It is also possible to experience a sudden onset of symptoms following food poisoning, abdominal surgery (such as C-sections, appendectomy, laparoscopy, etc) or a prolonged period of antibiotic treatment. Our podcast with Dr Allison Siebecker on understanding SIBO is a great place to start if you think you may have it. Listen here.

The common symptoms experienced by those with SIBO include:

✓ Bloating ✓ Heartburn/acid reflux
✓ Cramping ✓ Fatigue
✓ Constipation ✓ Chronic digestive complaints
✓ Diarrhoea ✓ Abdominal cramping and pain
✓ Alternating constipation and diarrhoea ✓ Joint pain
✓ Food sensitivities ✓ Skin rashes (such as eczema, hives, rashes)
✓ Belching and flatulence ✓ Iron and B12 deficiency
✓ Nausea ✓ Respiratory symptoms (such as asthma)
✓ Mood symptoms (such as depression, anxiety)  ✓ Brain symptoms (such as autism)

What are the common causes and risk factors for developing SIBO

Before we look at the risk factors, it’s important to understand the underlying causes of SIBO. There are many risk factors but only a few causes. 

Things do go wrong in the body and the way that the body protects itself can fail. One of the most common is the deficiency of digestive motility, called the migrating motor complex. The migrating motor complex function is to clear the small intestine of bacteria and any sort of indigestible food residue. As Dr Allison Siebecker explains, ‘It’s like a housekeeping wave, tidying up, making sure that everything is fixed up’. The migrating motor complex only works when we are fasting.  This occurs when we are asleep or between meals.  It is for this reason that people with SIBO are generally advised to eat every 4-5 hours and fast for 12 hours overnight.

The two most common underlying causes of SIBO are either a structural or functional abnormality of the small intestine.

  • Functional - A deficient migrating motor complex. It isn’t working properly because it’s deficient or works improperly. Listen here for Dr Allison Siebecker’s podcast on the migrating motor complex.
  • Structural - A structural problem, a partial obstruction, something clogging the clear passage of the bacteria, or an adhesion that could be blocking the way. Listen to our podcast with the Wurn’s on adhesions here for further information.

Check out our handy SIBO risk factors download here

SIBO Causes and Risk Factors

There are many risk factors that can lead to the migrating motor complex not working properly or there being a structural issue with the small intestine, ultimately leading to SIBO. These include:

✓ Food poisoning ✓ Surgical intervention and operations to the abdomen. Eg. Appendectomy, C-section, etc.
✓ Gastroenteritis ✓ Endometriosis
✓ Gastrointestinal infection ✓ A dysfunctional ileocecal valve
✓ Acid blockers or proton pump inhibitors (PPIs) ✓ Hypothyroidism
✓ Pain medication ✓ Stress
✓ Initial poor colonisation of gut bacteria due to cesarean birth and/or lack of breastfeeding ✓ Diabetes

What conditions are commonly linked to SIBO?

There are a number of conditions associated with SIBO.  If you have one or more of the following conditions, your risk of also having SIBO is considerably higher than the normal population.

✓ Irritable Bowel Syndrome (IBS) ✓ Acne rosacea
✓ Acid reflux ✓ Hyperthyroidism
✓ Coeliac disease ✓ Scleroderma
✓ Chronic Fatigue Syndrome ✓ Chronic Prostatitis
✓ Fibromyalgia ✓  Non-alcoholic Steatohepatitis (NASH)
✓ Chronic constipation ✓ Liver cirrhosis
✓ Inflammatory Bowel Disease (e.g. Crohn’s and ulcerative colitis) ✓ Diverticulitis
✓ Restless leg syndrome ✓ Diabetes


Should I test for SIBO?

If you’ve read through the symptoms and risk factors and realise they sound just like you, what’s next?  It is important to be tested for SIBO before commencing any treatment. SIBO can be a chronic and often complicated condition to treat, so understanding what type of SIBO you have is important. There are two types of SIBO, methane or hydrogen dominant, we’ll talk about the differences between these in Part 2 next week. 

A great next step is to take the free online SIBO quiz by SIBOTest, which gives you an indication of the likelihood of SIBO being present.  Take the quiz here.

Next, it’s important to find a practitioner who is experienced in treating SIBO. Finding the right practitioner can be the key to finding success on your SIBO journey. It’s important to remember that we’re all on different journeys; some people will need to find someone nurturing and comforting and others will need someone straightforward and to the point. If you need help finding a practitioner then a good place to start is the SIBOTest website where they have a list of SIBO practitioners.

The right practitioner will be someone who listens to you, shows understanding, has expertise and a depth of knowledge on SIBO, and can make you feel at ease with them. SIBO is a long-term, chronic condition for two-thirds of all patients (meaning those people won’t get rid of it quickly) and the chances are that by the time you come to see a practitioner, you’ve been feeling pretty rotten for some time.  Check out our podcast on finding your dream healthcare team here.

Rebecca Coomes The Healthy Gut Blog Post What You Need To Know About Sibo I Blog 1

How to test for SIBO

SIBO breath test

The majority of people are tested for SIBO using a  breath test. A glucose or lactulose sugar solution is drunk, with breath samples collected every 20 minutes, measuring the hydrogen and/or methane expired through the lungs. These gases are only produced by bacteria, not us, so their presence indicates the presence of the bacteria in the gastrointestinal (GI) tract.  Depending on what time the gases appear on the test, will help your practitioner determine where in your GI tract the overgrowth of bacteria is.  For instance, if there is a sharp rise early on in the test, that could indicate the overgrowth is higher up in the small intestine.

The breath test is currently considered the most reliable and non-invasive way to diagnose SIBO and is by far the most common way to test for SIBO.  It can be conducted at home or in-clinic, making it easily accessible.  Lactulose is non-absorbable and traverses the entire length of the small intestine, whereas glucose is absorbed in the first 2-3 feet of the intestine, so can only measure SIBO that is in the top section of the small intestine. It is for this reason that testing with both glucose and lactulose is often recommended for comprehensive results.  

It is also recommended that the test is undertaken over a 3-hour period, with breath samples collected every 20 minutes, to measure the gas output over a longer transverse time.  Shorter tests can be conducted, but they may provide a false negative if the SIBO is present in the lower section of the small intestine. Fructose malabsorption is often tested in conjunction with a SIBO test to determine if fructose is problematic.

Small Intestine Aspirate

An aspirate can be taken from the small intestine.  This can be performed by an endoscopy in-clinic, generally under anaesthesia.  A sample is taken and the culture is grown to determine what bacteria are present.  This test is invasive, costly and difficult to find because it requires a highly skilled medical professional to undertake the test.  For these reasons, it is not commonly used.


Stool Testing

Stool tests can be used to determine the bacteria found predominantly in the large intestine.   Whilst useful for understanding a broader picture of GI health, a stool test cannot diagnose SIBO, as it can’t identify if there is an overgrowth of bacteria in the small intestine, as it is difficult to determine where the overgrowth is occurring. If a breath test is not an option (for instance for very young children who cannot blow into a breath test), this can be an indicative starting point until a breath test or other culture can be taken.


Urine Organic Acids Test

Bacteria and fungus produce organic acids which are excreted in your urine.  A urine organic acids test measures the level of organic acids excreted, giving you an indication that you may have a yeast or bacterial overgrowth.  However, like the stool test, it is unable to pinpoint exactly where the overgrowth is occurring, and for this reason, isn’t used to definitively diagnose SIBO.


This article is Part 1 of a two-part series on SIBO. Head over to Part 2 to read more about the differences between methane and hydrogen dominant SIBO, SIBO treatment options and the 5 Key Pillars to Health.

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7 thoughts on “What you need to know about SIBO – Part 1”

  1. Hi Rebecca I have sibo and I do not know what to eat .I wanted to get your book called The healthy gut book Because it seemed like the best one but I couldn’t find it .If you can help I would appreciate it.Where do you live? I live in Vernon B.C Canada

    1. Hi Beverley
      Thanks for expressing interest in my books. All of my current books are available in my online store. The book called The Healthy Gut hasn’t been released yet, which is why you can’t find it. It also won’t be a cookbook so if you’re looking for recipes, I’d recommend looking through one of my 4 SIBO cookbooks here: http://thehealthygut.com/sibo-shop-2/

  2. Hi Rebecca after suffering years of misery with gut issues I am awaiting results of my breath test, which I am sure is SIBO. Would live some info on cooking meals/lessons via skype? Thank you so mu h Caroline

  3. Hi Rebecca I have been diagnosed with IBS and I am experiencing most of the SIBO symptoms, but I have tested negative for hydrogen on two occasions after conducting breath tests.. Nothing was reported about methane? Should I conduct another test and ensure I am tested for methane as well?

    1. Hi Brad, if I were you I would ask to be tested for methane. There are people who have very low hydrogen numbers, so test negative when only hydrogen is tested for, but have methane-dominant SIBO. Also, the methanogens (the little critters) consumer 4 parts hydrogen to make up 1 part methane, so you could also show as a false negative for hydrogen – it’s just that the methanogens consume the hydrogen before it appears on a test.
      But SIBO isn’t the only thing that can cause IBS symptoms so if you test negative for both hydrogen and methane, then it would be worth continuing your investigations, but it’s good to know SIBO isn’t the cause.

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