Cause Of Irritable Bowel Syndrome

A Cause Of Irritable Bowel Syndrome: Mast Cell Activation

Do you live in Ottawa? Are you looking for the cause of Irritable Bowel Syndrome?

If so, you are in the right place.

Today, I will discuss the role of mast cell activation as a cause of Irritable Bowel Syndrome.

In This Article:

Let’s begin by looking at what mast cells are.

What Are Mast Cells?

Mast cells are essential and are found in many of the body’s barriers, including the skin and the mucosal lining of the digestive tract.

Mast cells also affect systemic immune responses to pathogens such as bacteria or viruses.

Mast cells can be activated by a wide range of factors, some of which we will talk about later.

They also produce a wide range of immune mediators (small proteins) responding to an invader (e.g., microbes).

Abnormal, chronic activation of mast cells can contribute to a wide range of conditions, including the following:

  • Mastocytosis
  • Mast Cell Activation Syndrome (MCAS)
  • Respiratory conditions such as seasonal allergies
  • Skin conditions such as Eczema
  • Gastrointestinal disorders

Let’s look at what symptoms chronically activated mast cells play a role in different parts of the GI tract.

What Symptoms To Chronically Activated Mast Cells Produce In The GI Tract?

The chronically activated mast cells produce the following symptoms in The GI tract:

  • Esophageal – heartburn, dysphagia, globus and chest pain.
  • Stomach – Dyspepsia
  • Small and Large intestine – Abdominal pain and discomfort, diarrhea and constipation.

Many of these symptoms overlap common GI conditions such as IBS or Irritable bowel syndrome.

This similarity can make diagnosis difficult; however, we will discuss how, rather than mast cells being a separate cause, they may play a role in the mechanism that produces IBS symptoms.

Let us examine how mast cells orchestrate the immune system’s response to pathogens.

How Mast Cells Orchestrate The Immune Systems Response To Pathogens In The Gut

Mast cells orchestrate the immune system’s response to invaders in the gut by stimulating the release of various immune mediators.

An example of an invader in the gut is food allergies and sensitivities, which stimulate the release of IgE and IgG antigens.

These antigens attach to the Mast cell and stimulate an immune response, including the following:

  • B and T cells are part of your frontline or Adaptive immunity.
  • Mast cells can affect the permeability of the cells that line the gut leading to fluid moving into the gi tract and bloating.
  • Neutrophils, Dendritic cells and Macrophages kill pathogens in the gut.
  • Cytokine and mucous production produce an increased inflammatory response in the gut.
  • Mast cells also play a role in the leaky gut by affecting the Epithelial cells.
  • Mast cells affect the smooth muscle in the gut lining causing poor gut motility and visceral Hypersensitivity. Poor gut motility can lead to IBS.

Let’s examine and look at now what GI conditions are commonly associated with mast cell activation.

What Conditions Are Commonly Associated With Mast Cell Activation?

The GI conditions associated with mast cell activation are split into two main categories, including the following:

Functional GI Disorders

  • Irritable Bowel Syndrome
  • Functional Dyspepsia – recurring symptoms of an upset stomach that have no apparent cause.

Adverse Food Reactions

  • Food Allergies
  • Food Sensitivities
  • Food Intolerances

Let’s look at the growing scientific evidence of the association between IBS and activated mast cells.

The Growing Scientific Evidence Of An Association Between IBS And Mast Cell Activation

There have been several recent scientific papers concluding an association between IBS and mast cell activation, including the following:

Let’s now look at what factors and mechanisms underlie mast cell activation in the gut.

What Factors And Mechanisms Underlie Mast Cell Activation In The Gut?

Several factors underlie mast cell activation in the gut, including the following:

  • Gastroenteritis or food poisoning
  • Dybiosis includes the overgrowth of bacteria (e.g. staph aureus), h.pylori, Candida and parasites.
  • Chronic stress
  • Past emotional and physical trauma
  • Food allergies and sensitivities

Let’s now summarise what we have found.

What Have We Found?

GI infections and mast cells may play a role in food-triggered symptoms in patients with functional disorders such as IBS (via local IgE responses).

Dybiosis (e.g. Staph Aureus overgrowth) may prime mast cell activation, further promoting food antigen-triggered symptoms.

Now It’s Over To You

Do you suffer from IBS?

Do you understand more about the role of mast cell activation as a cause of irritable bowel syndrome?

Leave me a comment below.

Do You Need Help?

If you need help, I suggest you book a free functional medicine discovery session with me to determine whether my functional medicine approach fits your child’s needs.


The information provided on this website is for educational purposes only and is not intended to diagnose or treat any disease. Please do not apply this information without first speaking with your doctor.

Saccharomyces Boulardii Is Good For SIBO

Latest Research: Saccharomyces Boulardii Is Good For SIBO

Do you live in Ottawa? Are you wondering whether the probiotic Saccharomyces Boulardii is good for SIBO?

If so, you are in the right place.

Today I will talk about some latest research that shows that the probiotic Saccharomyces Bourlardi is good for SIBO.

In This Article:

Let’s begin by describing what SIBO is.

What Is SIBO?

SIBO, or Small Intestinal Bacterial Overgrowth, is a condition in which there is an overgrowth of bacteria in the small intestine, leading to symptoms such as heartburn, bloating, diarrhea, and constipation.

The small intestine is where most of our calories and nutrients are absorbed, so the inflammation from SIBO can lead to malabsorption issues.

Furthermore, the small intestines have the body’s highest percentage of immune cells.

SIBO can cause these immune cells to trigger inflammation, affecting the rest of the body.

This inflammation can cause symptoms such as non-alcoholic fatty liver disease, skin issues, body odour, depression, metabolic disorders, and even malabsorption of thyroid medication.

Let’s look at what Saccharomyces Bourlardi is.

What Is Saccharomyces Bourlardi?

Henry Bourlard discovered Saccharomyces Bourlardii.

Henry Boulard was travelling through Indo-China to discover a new type of yeast for winemaking.

Simultaneously, there was an outbreak of Cholera when Boulard observed that those who drank a particular tea did not have cholera-induced diarrhea.

Later, Boulard isolated the yeast used in the fermentation of the tea, which was Saccharomyces Bourlardi.

Since then, researchers have found Saccharomyces Bourlardi has anti-bacterial, anti-carcinogenic, and anti-parasitic properties.

Because they have these properties does not mean they are effective as a treatment.

A double-blind, randomized clinical trial is the best scientific way to show the effectiveness of a particular treatment.

Let’s look at a recent study examining whether Saccharomyces Bourlardi’s is good for SIBO.

Latest Research: Saccharomyces Boulardii Is Good For SIBO

A recent study published in January 2023 looked at the effect of Saccharomyces Bourlardii plus a Low Fodmap diet on people with bacterial overgrowth associated with IBS-D and its impact on the intestinal microbiota.

The results of the study showed the following:

  • Reduced Bacterial Overgrowth in the Small Intestines
  • Reduced Abdominal Pain
  • Reduced Diarrhea
  • Restoration of the Microbiota

The study comprised two groups, one on the low Fodmap diet and the other on Saccharomyces Bourlardii plus a Low Fodmap diet.

After two weeks, researchers saw a 40% improvement in SIBO for people on Saccharomyces Bourlardii plus a Low Fodmap diet and 30% for people on the low Fodmap diet.

This confirms typical clinical findings that people usually see symptom improvements after 2-3 weeks.

The typical time to expect optimal symptom changes when taking probiotics is 2-3 months.

Let’s now look at a simple protocol based on the above study.

A Simple SIBO Treatment Protocol Using Saccharomyces Bourlardii.

Based on the study, I recommend taking a Saccharomyces Bourlardii supplement such as Floramyces, one capsule twice daily.

If you do not see any change in your symptoms by the two-week mark, I recommend trying a different type of probiotic.

The two other types of probiotics include the following:

If you see improvements, continue for 2-3 months or until symptoms level out.

If some symptoms remain, you could try introducing another type of the types of probiotics.

Note: If you start a probiotic and get digestive upset for more than 2-3 days, change to a different type.

Now It’s Over To You

Do you suffer from SIBO?

Have you tried taking Saccharomyces Bourlardii?

Did it help your symptoms?

Leave me a comment below.

Do You Need Help?

If you need help, I suggest you book a free functional medicine discovery session with me to determine whether my functional medicine approach fits your child’s needs.


The information provided on this website is for educational purposes only and is not intended to diagnose or treat any disease. Please do not apply this information without first speaking with your doctor.

2 Best Leaky Gut Tests - Dominick Hussey - Functional Medicine

2 Best Leaky Gut Tests

Susan was experiencing severe bloating, gas and diarrhea. She had been to see her GP, 3 Gastroenterologists. All her tests were normal including bloodwork, an endoscopy and a colonoscopy. No one could explain her symptoms. Like most people in her position, Susan began to look for answers on the internet. Eventually, she came across an article on a condition known as leaky gut. Her symptoms appeared to match those of leaky gut. Her question was what were best leaky gut tests.

In this article, we will cover the fundamentals basics of leaky gut, is testing for leaky gut a good idea, and the two best leaky gut tests.

The Fundamentals of Leaky Gut

A leaky gut is a popular term that describes a condition where the lining of the intestines is not functioning correctly. The correct medical term for leaky gut is increased intestinal permeability.

The intestinal lining covers a surface area of about 400 metres squared and requires about 40 per cent of the body’s energy expenditure.  That is pretty extraordinary when you think that the brain needs only 20 per cent of the body’s energy expenditure.

This fact tells us that the intestinal lining is essential to our health.

The gut is a hollow tube that connects the mouth to the anus.  So, everything that is inside of the gut is technically outside of the body. Therefore everything that is inside of the gut is not technically inside of the body.

Therefore anything that is in the gut to move into the body has to cross that intestinal lining. A fundamental function of the intestinal lining is to let in things that should get in and keep out things that should not stay out.

When certain conditions are present, the intestinal lining’s capability of doing that task breaks down, and then all kinds of problems can happen.

Many factors can interfere with the function of the intestinal lining including:

  • A western-type inflammatory diet, lacking in fermentable carbohydrates and fermented foods
  • Bacterial, viral, parasitic infections
  • Fungal overgrowth
  • Heavy metals
  • Mold
  • Certain medications like proton pump inhibitors, antibiotics, or NSAIDs
  • Lifestyle factors like chronic stress or sleep deprivation or inappropriate physical activity, like too little or too much
  • Inadequate immune stimulation during our developmental period. Insufficient immune stimulation is known as the hygiene hypothesis. Better hygiene has done a lot to reduce acute infections, but these overly sterilised environments may have contributed to immune dysregulation because our immune systems aren’t adequately stimulated.

There are other factors which we call endogenous factors. Endogenous means they are factors that occur inside of the body that can contribute to leaky gut.

Endogenous factors include chronic inflammation, SIBO, or gut-brain axis problems

Is testing for leaky gut a good idea?

In my opinion, a leaky gut is almost always a symptom of a deep-seated underlying issue, meaning that the underlying problem comes before a leaky gut.

Causes of a leaky gut may include any of above factors that interfere with the function of the intestinal lining.

One of the critical principles of functional medicine is that we want to get to the bottom of what is causing symptoms or even manifestations of a disease. We want to remove or address those causes or triggers before we try to do anything about the symptom or the sign. The more we can get to the root of the problem, the more effective the intervention will be.

In other words, by suppressing symptoms, it is going to be less effective, and will not last for as long because we have not addressed the underlying cause.

So with intestinal permeability, if we remove the triggers that are causing leaky gut in many cases, you will not need to address intestinal permeability because it will take care of itself.

One of the astonishing things about the cells in the gut is they regenerate every two to three days. Therefore if you remove the triggers that are causing the problem, the cells will revive and the tight junctions can restore themselves, and the intestinal permeability will disappear.

Hence typically in my practice clinic, before looking at a leaky gut, I will test and treat the triggers such as food sensitivities, gut infections and stress. If the patient is still having problems that we could associate with leaky gut, at that point, I will consider testing for intestinal permeability.

Testing options for intestinal permeability

If you look at the research, many different leaky gut tests have been used to define or identify intestinal permeability. Some of these are more common than others, but I am just going to mention a few different ones, and then I will tell you what I use in my practice and what I recommend.

The first is the lactulose/mannitol permeability assay. This test uses molecules, sugars, long-chain sugars called oligosaccharides, and I will explain a little bit more about that in a later.

The second test is an antigenic permeability screen. This test looks at antibodies to particular antigens like lipopolysaccharides and then also antibodies to endogenous molecules like actomyosin, occludin and zonulin. These are proteins that the body produces in the gut that help to regulate tight junction permeability, the structure of the gut and determine whether the gut is permeable or not.

The next marker that researchers sometimes use in studies is an organic acid called D-lactate or D-lactic acid. D-lactate is different from lactic acid that you may have heard about that can be high after exercise. This organic acid is a product of bacterial metabolism which is produced in the gut. Some studies have shown a correlation between high D-lactate and increased intestinal permeability.

Butyrate, which is a short-chain fatty acid, has been investigated as a potential marker for intestinal permeability. Low butyrate is a sign of leaky gut.

Finally, zonulin is a protein that regulates the tight junctions in the gut has been investigated as a marker for intestinal permeability.

What Are The Best Leaky Gut Tests?

In terms of clinical practice and what is readily available and has been most validated by the scientific research, the lactulose/mannitol test and the antigenic permeability screen are the two best leaky gut tests.

The Lactulose/Mannitol Test

The lactulose/mannitol test involves measuring levels of two sugars in the urine after the patient consumes those sugars. By looking at the ratio of the two sugars in the urine you can tell you whether the gut is permeable.

The lactulose/mannitol test is available through Genova Diagnostics.

There are some shortcomings of lactulose/mannitol testing.

One of the issues is that the transport of lactulose or mannitol through the gut barrier is not actually or not necessarily an indicator of a malfunction of the intestinal tight junctions. In other words, a positive result doesn’t necessarily mean that there is intestinal permeability present.

There are a lot of variables that can influence the uptake of the sugars, like GI motility, use of medication like NSAIDs, the surface area of the intestine, gastric emptying, and mucosal blood flow so these variations can affect the result.

Another issue is that some studies have shown that only large molecules (over 5,000 daltons) can change the permeability of intestinal epithelial cells and then result in an inflammatory response in the body.

Lactulose and mannitol are below 500 daltons, which suggests that they may not be appropriate as challenge molecules for an intestinal permeability test.

There are ways to increase lactulose/mannitol testing accuracy including:

  1. Avoiding foods containing lactulose 24 hours before the test. Lactulose is found in heat-processed dairy and non-dairy beverages such as soy milk and some yoghurts.
  2. Avoid mannitol for 24 hours before the test. Mannitol is found in brown seaweed, celery, carrot, coconut, cauliflower, cabbage, pineapple, lettuce, watermelon, pumpkin, squash, cassava, pea, asparagus, coffee, olives and berries, and chewing gum.
  3. Avoid dairy products for 24 hours before the test.
  4. On the day of the test avoid drinking too much water.

The Antigenic Permeability Screen

The second test for leaky gut is called the antigenic permeability screen.  This test was developed by Doctor Aristo Vojdani at Cyrex Labs.

In large part, Dr Vojdani developed the test because of the shortcomings of the lactulose/mannitol test.

Doctor Vojdani wanted to create a test that would better reflect pathological permeability of the gut. So instead of using larger sugars, he decided to screen for antibodies to proteins and bacterial endotoxins, since those are the primary concern when it comes to immunoreactivity.

We know that the uptake of antigens, proteins and bacterial endotoxins, plays a significant role in the pathogenesis of a gastrointestinal and autoimmune disease.

Many studies are showing that the inappropriate transfer of proteins and endotoxins from the gut into the bloodstream initiates an inflammatory response and can contribute to autoimmune disease. This understanding explains the connection between leaky gut and autoimmune disease. Less than 10 per cent of subjects with a genetic susceptibility to autoimmune disease progress to having a clinical autoimmune disease in their lifetime. This fact suggests that environmental triggers like toxic chemicals and infections and dietary proteins are probably involved in the development of autoimmune disease.

The Antigenic Permeability Screen is a blood test. This test is only offered by one lab, Cyrex Labs, and is called Cyrex Array 2.

This test needs to be ordered by a healthcare practitioner who is registered with the Cyrex.

The test involves drawing a blood sample and then testing for antibodies to lipopolysaccharide, IgM, IgG and IgA antibodies,


In practice, for the reasons I explained above I do not check for intestinal permeability very often. Typically I tend to look at the underlying cause of intestinal permeability and address that first. So although the mannitol/lactulose and antigenic permeability screen are the best leaky gut tests, If I do a sound job with addressing the root, in most cases, the intestinal permeability will resolve on its own.

When I do test for permeability, I use the Cyrex test.



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

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5 Complications of SIBO - Dominick Hussey - Functional Medicine

5 Complications of SIBO

You will not die from SIBO, but it does lead to various complications. The main complications of SIBO include:

  • Nutrient Deficiency and Excess
  • Malabsorption
  • Increased Small Intestinal Permeability
  • Autoimmunity
  • Blunted Small Intestinal Villi

Read on to learn about the complications of SIBO occur in the body.

Vitamin B12  Deficiency

SIBO is known to cause a B12 deficiency in the scientific literature. Vitamin B12 deficiency happens in SIBO as a result of utilisation of the vitamin by bacteria. When bacteria take up the vitamin, the bacteria partly metabolise it to inactive analogues, which compete with normal vitamin B12 binding and absorption.

Symptoms of B12 deficiency may include things like neuropathy, cognitive decline, or even dementia.

There is a high prevalence of SIBO in the elderly. This fact could make you question whether the B12 deficiency seen in the elderly is related to SIBO and not just “ageing.”

Fat Malabsorption

SIBO can also cause fat malabsorption, which leads to a buildup of free bile acids. A build-up of bile leads to mucosal inflammation can lead to increased intestinal permeability. Increased intestinal permeability aka leaky gut can lead to autoimmunity.

Fat malabsorption can also lead to a decline in the absorption of fat-soluble vitamin including:

  • Vitamin D and K2 which will cause osteoporosis
  • Vitamin A which will cause night blindness and retinopathy
  • Vitamin K leading to prolonged clotting times

Stunted Small Intestinal Villi

SIBO can lead to blunted small intestinal villi that will decrease the activity of disaccharides. Disaccharides are enzymes that are required to break down carbohydrate.

A reduction in disaccharide activity will lead to carbohydrate malabsorption. Carbohydrate malabsorption will lead to a build-up of carbohydrates in the small intestine. The bacteria in the small bowels feed on carbohydrates.

So blunted intestinal villi will lead to increase the number of bacteria so worsening the SIBO.

Protein Malabsorption

Bacteria digest protein. When you have too much bacteria in the upper part of the small intestine, where the protein is absorbed, then that will interfere with your absorption of protein.

Excess Folate

While B12 deficiency is prevalent with SIBO, folate levels can often be high in SIBO because of increased synthesis of folate by small intestine bacteria.


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

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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.

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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.

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