Visit our Location
356 MacLaren Street, Ottawa
Give us a Call
613 230-0998
Send us a Message
3 Primary Causes of SIBO - Dominick Hussey

3 Primary Causes of SIBO

The causes of SIBO or Small Intestinal Bacterial Overgrowth and how it develops is not entirely clear, and it’s still somewhat debatable. SIBO begin when there is a disruption in the mechanisms that control the number of bacteria that live in the small intestine. There are at least seven risk factors that are potential causes for that disruption.

  • Structural or anatomic issues, for example, after surgery, if there was damage to nerves that enervate the small intestine, or patients with Cystic Fibrosis
  • Motility disorders, so dysfunction of the migrating motor complex
  • Irritable bowel syndrome
  • Metabolic diseases like diabetes
  • Low stomach acid
  • Age
  • Organ system dysfunction
  • Medications

The 3 Primary Causes of SIBO

According to Chris Kresser, Functional Medicine and SIBO expert, three primary processes cause SIBO:

  • Low gastric acid secretion
  • Small intestine dysmotility
  • Disrupted microbiota

Low gastric acid secretion

Stomach acid suppresses the growth of ingested bacteria, which would limit bacteria in the upper small intestine. For this reason, hypochlorhydria, or low stomach acid, is a primary risk factor for SIBO.

Low stomach acid can develop:

  • When H. pylori bacteria are present
  • With chronic stress
  • As a consequence of ageing

There are also drugs that inhibit acid secretion, like histamine type 2 receptor blockers, and Proton Pump Inhibitors, both of which are used to treat heartburn and GERD.

If a person has heartburn and they take these acid-suppressing drugs for a significant period, it reduces stomach acid it may predispose them to develop SIBO.

Small intestine dysmotility

The next primary of the causes of SIBO is impaired intestinal motility or dysfunction of the migrating motor complex (MMC). The MMC sweeps residual debris through the gastrointestinal tract so abnormalities in the MMC may predispose to the development of SIBO.

Disrupted microbiota

The third of the primary causes of SIBO is a disrupted gut microbiome, but there is less research on this proving a direct cause. There are however several lines of evidence that support an association.

One is that it’s well-established that antibiotic use can lead to disrupted gut microbiome and in turn SIBO.

Celiac disease also leads to a disrupted gut microbiome, and there’s a definite connection between celiac and SIBO.

Disrupted gut microbiome has been shown to cause dysfunction of the ileocecal valve, and we know that dysfunction of the ileocecal valve can lead to translocation of bacteria that should stay in the large intestine into the small intestine, which is one of the principal ways that SIBO develops.



This article is not intended to provide medical advice, diagnosis or treatment.

Now I’d like to hear from you. Let us know in the comments below.


Like what you’ve read? Sign up for FREE updates delivered to your inbox.

* indicates required


What is the Correct Definition of SIBO - dominick Husey

What is the Correct Definition of SIBO?

There are several different definitions of small intestinal bacterial overgrowth (SIBO). Part of the challenge of dealing with it is that there isn’t even really a consensus on how to define it. On the simplest level, it indicates the presence of excessive bacteria in the small intestine. But what is the correct definition of SIBO?

In this article, I discuss the different ways parameters or measures scientists have explored (at the time of writing) to find a correct definition of SIBO.

The Number of Bacteria

A more specific definition of SIBO is where the number of bacteria in the small intestine exceeding 105 to 106 organisms per millilitre. Usually, there should be less than 103 organisms per millilitre found in the upper small intestine, and the majority would be gram-positive. But this specific definition of SIBO relies on endoscopy, which is one of the two test methods used to detect SIBO, but it’s the least frequently used. In fact, I can not think of any Functional Medicine practitioner, that is using endoscopy to diagnose SIBO, so it’s not that helpful of a definition for our practical perspective.

The Type of Bacteria

In addition to the absolute number of bacteria in the small intestine, the type of flora also plays a role in the signs and symptoms of SIBO. The predominant bacteria metabolize bile salts to unconjugated or insoluble compounds, and that can cause fat malabsorption or bile acid diarrhea.

Microorganisms that preferentially metabolize carbohydrates to short-chain fatty acids in a gas can cause bloating without diarrhea. Whereas gram-negative bacteria that are overgrown in the small intestine like Klebsiella can produce toxins that damage the mucosa and interfere with nutrient absorption.

This explains why people with SIBO can have such a wide range of symptoms. It depends on which type of bacteria is overgrown in the small intestine. Again using the type of bacteria found in the small intestine to define SIBO relies on endoscopy.

Measuring Gases

The two main ways of testing for SIBO is through an endoscopy of the small intestine and a lactulose breath test. As mentioned above the former method is not practical. The breath test measures the quantity of hydrogen of methane produced in the small intestine. This method is relatively straightforward but there is no consensus on how to interpret the results. This lack of consensus makes it difficult to establish a firm definition based on the results of a breath test.


So what does this mean? There are three possible measures you could use to define SIBO: the number of bacteria, the type of bacteria and the gases produced in the small intestine. Using any of these measures to establish a correct definition is made difficult because of the limitation of the two main testing measures. It is my observation that currently, the majority of Functional Medicine practitioners (including myself) use the more practical breath test results to diagnose SIBO.



This article is not intended to provide medical advice, diagnosis or treatment.

Now I’d like to hear from you. Let us know in the comments below.


Like what you’ve read? Sign up for FREE updates delivered to your inbox.

* indicates required


7 Little Known Warning Signs That You Have SIBO

7 Little Known Warning Signs That You May Have SIBO

SIBO or Small Intestinal Bacterial Overgrowth is characterised, as the name implies, by excessive bacteria in the small intestine.

Typical symptoms of SIBO include bloating, gas and constipation and or diarrhoea.

If you thought that not having any of these symptoms meant you do not have SIBO, think again.

There is a growing amount of evidence to show that SIBO can manifest with symptoms both inside and outside of the gut. Read on to find out more about some of the little-known signs and symptoms of SIBO that I observe every day in my practice.

Do you Burp after meals?

The majority of your friendly bacteria or microbiota should reside in your large intestine. Your small intestine should be virtually sterile.

One of the main occupations of the microbiota is to breakdown fermentable carbohydrates and produce valuable nutrients for your body as well as gases.

When SIBO occurs your microbiota overgrows from your large intestine to your small intestine. The microbiota that now lives in your small intestine continues to feed on these carbohydrates and produce gases.

These gases become partially trapped in the small intestine leading to the typical bloating and gas.  These gases are expelled upwards causing burping.

So, if you find yourself burping a lot especially after eating, this could be a symptom of SIBO.

Do you experience Fibromyalgia symptoms?

Fibromyalgia symptoms include chronic muscle pain and stiffness, especially across the upper back, neck and shoulders. There has been growing evidence of a link between Fibromyalgia and SIBO two studies published in the Annals of Rheumatic Disease, researchers from the Cedars-Sinai Medical Center found a direct association between subjects with fibromyalgia and SIBO. (1) (2)

Do you get Interstitial cystitis?

Interstitial cystitis (IC) is a chronic condition causing bladder pressure, bladder pain and sometimes pelvic pain. A large number of people who suffer from IC have SIBO. In a study published in Digestive Diseases and Sciences, researchers found 81% of 21 subjects with IC tested positive for SIBO. (3)

Are You Lactose Intolerance?

People with lactose intolerance are unable to completely digest lactose. Lactose is a sugar found in milk. A small but significant amount of people with a lactose intolerance also has SIBO. In a study published in the Saudia Arabia Journal of Gastroenterology, researchers found that 18% of subjects with IBS were also lactose intolerant. (4)

Do you have chronic low Iron and or B12?

You may have SIBO if you suffer from chronic low B12 or iron that does not increase with supplementation. It is thought that the bacteria that have overgrown into the small intestine take up nutrients such as B12 and iron before they can be absorbed. (5)

Do you suffer from Restless Legs?

Restless legs syndrome (RLS) is a condition in which you have an uncontrollable urge to move your legs. It typically occurs in the evenings while you’re sitting or when you first lie down to go to bed. Recent research has found a strong association between IBS and RLS. In a study published in 2012, researchers found that 25% of people with RLS suffered from SIBO compared to 6.5% of controls. (6)

Do you have Diabetes?

If you have been diagnosed diabetes and suffer from digestive symptoms then you may have SIBO. A recent study observed that SIBO was present in 43% of diabetic patients with chronic diarrhea, and 75% had a positive change in their symptoms after being treated with antibiotics. (7)


If you suffer from any of the above conditions with or without other digestive symptoms then I suggest that it worth looking into the possibility you have SIBO.

SIBO is diagnosed using a Lactulose breath test.


This article in not intended to provide medical advice, diagnosis or treatment.

Now I’d like to hear from you. Do you suffer from any of the above conditions? Have you heard of SIBO? Let us know in the comments below.


Like what you’ve read? Sign up for FREE updates delivered to your inbox.

* indicates required


What diet is best for IBS

How to choose the best diet for IBS?

Is there a best diet for IBS? The answer is: it depends.

The actual cause of IBS, short for irritable bowel syndrome,  is unknown although there have been numerous factors associated with it including food sensitivities, epigenetics, nutritional deficiencies, genetics and psychological stress. (1)

In my clinical experience, there is never one single cause for a condition it always a blend of factors.

The food we eat can often be a common constituent of this blend but deciding which foods are triggering your IBS symptoms can be confusing.

Read on to learn about the most clinically and scientifically valid diets for IBS and how to work out the best diet for you.

Diets for IBS

There are various of diets that have been shown either clinically or through scientific research to help with symptoms of IBS. In this next section, I will briefly outline each of these diets, beginning with the simplest.

A Gluten Free Diet

Gluten is a protein found in the protective casing around all grains. The most well known and most toxic glutens include:

  • Wheat gluten.
  • Barley gluten.
  • Rye gluten.
Other less well known but potentially harmful glutens are found in Spelt, Kamut, farro and durum.
If you suspect that gluten may be triggering your IBS symptoms, it is crucial that when following a gluten free diet you exclude all the above grains.

It is a well known scientific fact that gluten is associated with IBS. (2) A gluten-free diet has also been shown to help with IBS symptoms. (3)


FODMAP is an acronym, for a group of carbohydrates, which stands for Fermentable, Oligosaccharides, Disaccharides, Monosaccharides and Polyols. These carbohydrates are found in various foods and alcohols including:

  • Oligosaccharides –Fructans and Galacto-oligosaccharides found in wheat, rye, barley, onions, leek, shallots, garlic, legumes, lentils, artichokes, and chicory.
  • Disaccharides – Lactose found in dairy products.
  • Monosaccharides – Fructose found in honey, mango, watermelon, apples, pears, and high fructose corn syrup.
  • Polyols – Alcohols found in Apples, pears, apricots, nectarines, plums, cauliflower, products (e.g., gums & confectionery) sweetened with artificial sweeteners such as sorbitol known as polyols.

To download a more comprehensive list of FODMAP foods, please click here.

The low FODMAP diet has been shown to help IBS symptoms in several high-level clinical trials significantly. (4, 5)

FODMAPs are broken down by our friendly bacteria that normally reside in our large bowel.

In a significant percentage of people with IBS, these bacteria overgrow into the small intestine, known as small intestinal bacterial overgrowth or SIBO.

When the bacteria break down FODMAPs in the small intestine, they produce an excess of gases. These gases cause the symptoms of bloating and altered bowel function.

The diet is thought to help symptoms by starving the bacteria of FODMAPs.

It is important to see this diet as a short term measure to get symptoms under control since there concerns about the future health of the bacteria in the large bowel.

A Low Histamine Diet

Histamine is a compound produced by your immune system when it encounters an allergen.

Histamine Intolerance occurs where there is an excess production of histamine. Histamine intolerance has been associated with the development and severity of IBS. (6)

Histamine is found naturally in various foods and food additives.

In my clinical experience, I have observed IBS symptoms improve when clients have followed a diet low in histamine foods. A present there have no clinical trials to show that a low histamine diet helps with IBS.

A brief list of high histamine foods includes:

  • Leftover meats and fish
  • Processed or smoked meats
  • Fermented foods such as sauerkraut and kefir
  • Aged Cheeses and meats
  • Tomatoes and Avocados

To download a more comprehensive list of high histamine foods, please click here.

How to choose the best diet for IBS

If you suffer from IBS and are confused by which of the above diets to follow I suggest taking a simple step by step approach.

Begin by putting yourself on a gluten-free diet for at least two weeks. If your symptoms totally disappear, then you have your answer.

If your symptoms only partially improve, I suggest starting the low FODMAP and following that for another two weeks.

If your symptoms significantly improve, then this would strongly suggest that you may have SIBO. In such case, I recommend that you seek out a health professional, such as a Functional Medicine Practitioner or Naturopathic Doctor, that has experience in diagnosing and treating SIBO.

If your symptoms only partially improve, I suggest moving to a low histamine low FODMAP diet for another two weeks. If your symptoms significantly improve, then this is also a strong indication of SIBO.

To download a more comprehensive list of Low FODMAP Histamine Diet, please click here.

If your symptoms do not improve on the Low FODMAP Histamine diet, I strongly recommend you go to your doctor and ask to be referred to a GI specialist for further investigation including a colonoscopy.


This article in not intended to provide medical advice, diagnosis or treatment.

Now I’d like to hear from you. Do you suffer from IBS? Have you been confused about what diet to try? Do you have any other suggestions that have worked well for you? Let us know in the comments below.


Like what you’ve read? Sign up for FREE updates delivered to your inbox.

* indicates required


signs of sibo

SIBO: Everything you need to know

Have you ever consumed some food or drink and within a few hours seen that your belly is so bloated that you can’t fasten your pants? It’s not unusual for my clients to inform me that they get up with a flat tummy and by the close of the day they look seven months pregnant. Even if you haven’t endured abdominal swelling to such an extreme, any amount of bloating is not healthy, and it is a mark of intestinal inflammation. If you’re producing gas and bloating frequently, you could have food sensitivities and a gut infection, such as SIBO.

What is SIBO?

SIBO or Small Intestinal Bacterial Overgrowth happens when the bacteria in our gut get out of balance and overgrow. Most of your friendly bacteria should reside in your large intestine. When you have SIBO, these bacteria overgrow into your small intestine. This overgrowth occurs when you have a slowing down peristalsis through the digestive tract.

What causes weak peristalsis?

  1. Intestinal wall nerve damage, For example, diabetes mellitus and scleroderma can both affect the muscles in the gut.
  2. Scarring from surgeries or Crohn’s disease.
  3. Diverticulitis, which are tiny pouches that can form in the wall of the small intestine.
  4. Medications such as antibiotics, acid-blocking drugs, and steroids.
  5. A diet high in sugar processed carbohydrates and alcohol.

17 Signs Of Small Intestinal Bacterial Overgrowth (SIBO)

  1. Abdominal bloating
  2. Belching,
  3. Flatulence
  4. Abdominal pain or cramps
  5. Constipation and or Diarrhea.
  6. Heartburn
  7. Nausea
  8. Food Sensitivities
  9. Headaches
  10. Joint Pain
  11. Fatigue
  12. Eczema or rashes
  13. Asthma
  14. Depression
  15. Fatty stools – stools that float
  16. Iron Deficiency Anaemia or B12 deficiency that does not resolve with supplementation
  17. Weight Loss

How to test for SIBO

The gold standard test for testing SIBO is a lactulose breath test. This test is not readily available in Canada but can be obtained from labs in the US such as Genova Diagnostics.

If you have any questions about this article either post them in the comments section below or email using the form on my contact page.


This article in not intended to provide medical advice, diagnosis or treatment.