Small Intestinal Bacterial Overgrowth (SIBO) and Allergies
Most of us have experienced it at some point – the uncomfortable kind of bloating that makes you feel six months pregnant. If you’ve landed here, you may be wondering if you have food allergies and intolerances, or if there is something deeper going on.
When bloating starts to show up every day and brings its friends, farts and weird poos, suddenly you’re questioning every food and becoming wary of your jeans. The frustration only continues when all the tests come back normal and you’re lumped with the IBS label and told to put up with it.
What a lot of people haven’t heard about is a cause of bloating known as Small Intestinal Bacterial Overgrowth (SIBO). Exactly what it says on the tin, SIBO is an overgrowth of bacteria in the small intestine, where it shouldn’t be.
The large majority of our gut microbes comfortably reside in the large intestine, so when the amount in the small intestine increases to a problematic number, they let us know about it by fermenting our food and producing some nasty gas.
This leads to bloating, flatulence, burping, stool changes and other unpleasant experiences, both in the gut and other aspects of our health.
Where it gets complicated is SIBO can contribute to the development of allergies and food intolerances, which many of our Positive Association Technique (PAT) clients come to us with to seek relief.
What causes SIBO?
The causes of SIBO can be complex and multifactorial. The gist is that the body has a master plan in place to prevent bacteria from gathering in the small intestine, but when these mechanisms falter, SIBO can develop.
The two main methods of keeping SIBO at bay include a good amount of stomach acid and a strong cleansing wave moving through the gut.
Gastric juices such as stomach acid, enzymes and bile are responsible for restricting food borne bacteria from making their way into the intestines. Sometimes these digestive juices can be lacking, such as when stress or medications like proton-pump inhibitors reduce their output.
Additionally, a periodic peristaltic wave called the Migrating Motor Complex (MMC) passes through the small intestine in between meals. The MMC has been dubbed the “intestinal housekeeper” and helps keep SIBO at bay by moving bacteria towards the colon and preventing backflow.
Illnesses and structural abnormalities of the gut which affect motility can also contribute to SIBO, such as hypothyroidism, diabetes, diverticular disease, hypermobility disorders and abdominal surgery. Also, as we age both our motility and gastric acid production slow, making us more susceptible to SIBO.
SIBO is also more commonly found in people with certain health conditions, including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), Helicobacter pylori infection, obesity, liver disease, fibromyalgia, endometriosis, rosacea and dyspepsia.
Signs and Symptoms of SIBO
SIBO is a tricky beast and can present itself in a variety of ways depending on which type of bugs are present and which type of gas is produced.
Methane gas slows motility and contributes to constipation, whereas hydrogen gas often causes loose stools. It is also common to produce both gasses and have mixed stools.
Symptoms of SIBO can often include:
- Bloating, particularly uncomfortable fullness after eating
- Flatulence
- Burping
- Reflux
- Nausea
- Reduced appetite
- Constipation, diarrhoea or both
- Abdominal pain
- Nutrient deficiencies
- Weight loss
The flow-on effects of SIBO can also contribute to symptoms outside of the gut. For example, numerous studies show a link between SIBO and rosacea, acne, psoriasis and dermatitis, another sign of the gut-skin axis.
Other clues SIBO might be present include:
- Bloating and/or burping within an hour of meals
- Reacting to high FODMAP foods – as they are so widespread, it can feel like you are reacting to every food and make it difficult to pinpoint triggers
- Probiotics worsening symptoms
- Increasing fibre (or prebiotics in supplements) can worsen symptoms
- Improvement in symptoms when using antibiotics, even for a different issue
- Restless legs at night
- Chronic B12 or iron deficiency without other cause
- Gut issues starting with a bout of gastritis
- History of recurrent antibiotic use
- History of recurrent antacid use
The Link Between SIBO and Allergies
When gut symptoms are present it can be difficult to understand their origin – is it food allergies and intolerances, or SIBO?
We know that people with SIBO have low tolerance for FODMAP foods, as these fermentable carbohydrates are what the overgrowth of bacteria like to feast on most. But can we blame other food sensitivities on SIBO too?
The impact of SIBO on immunity and inflammation is complex and there are a few ways it can be linked to allergies and sensitivities.
Imbalanced gut bacteria
SIBO involves an excessive number of bacteria in the small intestine which are normally found in the colon, leading to imbalanced gut bacteria, also called dysbiosis.
The role of the microbiome in allergies has been widely studied, showing that through multiple pathways, dysbiosis can reduce tolerance to foods and lead to food allergies forming.
Studies on the gut microbiome of infants have connected it to the development of allergies later in life. Factors like antibiotic use can disrupt the microbiome, playing a role in both the development of SIBO and allergic conditions such as asthma and food allergies in childhood.
Evidence also points to a link between low microbial diversity in early life and the risk of allergies. This is a good reason to aim for a diverse plant-based diet from an early age.
Immune triggers and leaky gut
The overgrowth of bacteria associated with SIBO triggers mucosal inflammation in the gut by increasing lipopolysaccharide (LPS) levels. This activates a cascade of type 2 inflammatory immune cells which are involved in allergic reactions.
In addition to this, the local inflammation weakens the tight junctions between our gut cells, which form one of our best barriers against the outside world.
This is what we call leaky gut, also known as intestinal permeability, and means the LPS created in the gut is now able to move into systemic circulation, further continuing to fuel type 2 (allergic) inflammation.
Histamine intolerance
When it comes to SIBO and allergies, SIBO can contribute to histamine overload in a few ways. It can allow an overgrowth of certain bacteria which produce histamine, and damage from SIBO can reduce our ability to breakdown and clear histamine.
This can lead to histamine-induced food sensitivity symptoms such as headaches, sinus congestion, flushing, itchy skin, rashes or digestive upset.
Nutrient deficiencies
SIBO can affect absorption of nutrients in the small intestine, including those important for immune function and gut integrity, such as iron, B12 and zinc. This can further reduce our tolerance to foods and make symptoms harder to resolve.
It goes both ways
Another thing to understand is that the connection between SIBO and allergies, goes both ways.
While SIBO can trigger food sensitivities by the mechanisms mentioned, the low-grade inflammation caused by allergies can also worsen gut symptoms. This can create a cycle where symptoms can become more persistent and more difficult to manage.
Testing for SIBO
If you’ve been reading along nodding your head and feeling seen, then it could be time to investigate whether SIBO is a cause of your symptoms.
Visiting a GP and/or Naturopath well versed in SIBO is a great place to start. They can assess your symptoms and help prescribe the appropriate testing.
The gold standard for diagnosing SIBO is a small bowel aspirate culture, which takes a sample of fluid from the small intestine during an endoscopy, to measure the bacteria present.
Thankfully there is a less invasive option – a SIBO breath test which can be performed at home and sent to the lab. The breath test involves drinking a substance which the bacteria like to consume – typically lactose or glucose – and measuring the amount and type of gas produced over a 3-hour period as it travels through the small intestine to the large intestine.
A SIBO breath test result which is high in hydrogen is linked to a number of different bacteria such as E.coli, Klebsiella and Enteroccous and can contribute to diarrhoea or mixed stools (diarrhoea and constipation).
Whereas a SIBO breath test result showing high methane levels is often caused by an archaea known as Methanobrevibacter smithii, and is linked to constipation. As this type of SIBO is not caused by bacteria, but rather archaea, it has been renamed to Intestinal Methanogen Overgrowth (IMO).
SIBO Treatment Options
Once SIBO is identified, the goal is to target the overgrowth to reduce the problematic number of organisms in the small intestine.
Bacterial overgrowth can be targeted with specific antimicrobial herbs and/or a specific, locally acting antibiotic called Rifaximin. Rifaximin is a nonsystemic antibiotic which targets the SIBO with limited detrimental effects on the microbiome.
A low FODMAP diet or similar can often be used short term to reduce symptoms and inflammation caused by trigger foods.
Alongside all of this, we care for whole gut health with herbal and nutritional support for gastric juices, motility and the microbiome. These are important parts of the plan, assisting the treatment to work better, protecting beneficial bacteria and most importantly, helping to target the cause.
An essential part of treatment is understanding and addressing the cause, which can be different for each individual. As with all health conditions, if the cause goes untreated, the problem is likely to recur.
The Role of Positive Association Technique (PAT) with SIBO
Positive Association Technique (PAT) helps re-train the body’s response to food triggers using kinesiology, acupressure and positive conditioning.
Allergies and sensitivities can trigger chronic inflammation, worsening gut symptoms, increasing the histamine load and even contributing to leaky gut.
While working on SIBO naturopathically, PAT can be a gentle way to address reactions to triggers like pollen, dust mites, cats and grasses, to lighten the inflammatory load and help reduce the symptoms that weigh us down.
If you’re reacting to lots of foods, the goal is not to stop eating them but to correct the underlying gut issues which are causing them.
Working with a Naturopath and PAT Practitioner can help you get to the bottom of your symptoms for longer lasting results and ultimately, food freedom!
You can learn more about PAT;
- in our podcast episode – What is Positive Association Technique (PAT)?
- get a copy of our Free PAT Information E-Pack straight to your inbox
- Call our head office on 1300 853 023 (Aus) or 09 479 5997 (NZ) to chat to our friendly staff
Written by Leila DiQuinzio – Melbourne based Naturopath & PAT Practitioner
Leila is a degree qualified Naturopath with over 12 years of experience, and provides Positive Association Technique (PAT) from the multi-modality clinic she co-founded in Northcote, Melbourne named ‘Aēsara Health‘.
Please note that this blog post contains general information only. Always consult your health care professional before changing your diet, starting new supplements or regarding any medical condition.











