Did you know that in at least one-third of people with Irritable Bowel Syndrome (IBS), Small Intestinal Bacterial Overgrowth (SIBO) could be an underlying cause? Some studies suggest that SIBO might actually underlie up to 78% of IBS cases, depending on diagnostic methods. This often under-recognised condition may help explain why so many people with IBS experience persistent symptoms.
In at least one-third of people with Irritable Bowel Syndrome (IBS), Small Intestinal Bacterial Overgrowth (SIBO) could be an underlying cause.
What is SIBO (and IMO)?
SIBO
SIBO occurs when bacteria that typically reside in the large intestine begin to overpopulate in the small intestine. The small intestine is one of the main sites of nutrient digestion and absorption, typically containing far fewer bacteria than other parts of the gut. When bacteria proliferate here, they interfere with digestion and nutrient absorption, leading to uncomfortable symptoms like bloating, abdominal pain, and changes in bowel habits.
IMO
A closely related condition is Intestinal Methanogen Overgrowth (IMO), which involves an overgrowth of methanogens (microbes that produce methane) rather than bacteria. IMO often causes many of the same symptoms as SIBO, though it’s typically associated with constipation rather than diarrhoea.
Consequences of SIBO and IMO
The microbes involved in both SIBO and IMO ferment the food we eat, producing gases as a byproduct. This gas buildup can lead to symptoms like burping, discomfort, bloating, and flatulence. Additionally, the overgrowth from either SIBO or IMO can lead to inflammation in the small intestine and nutrient deficiencies over time, as nutrients aren’t effectively absorbed. This inflammation may also contribute to symptoms that affect the entire body, such as muscle pain, brain fog, and joint pain, highlighting how SIBO’s impact often extends beyond the gut.
Small Intestinal Fungal Overgrowth (SIFO)
In addition to bacterial overgrowth (SIBO), Small Intestinal Fungal Overgrowth (SIFO) can also occur in the small intestine. This condition involves an excess of fungi, such as candida, which can disrupt digestion and cause symptoms similar to SIBO, including bloating, gas, nausea and abdominal discomfort. While testing for SIFO can be challenging, a comprehensive stool test may provide valuable insights by identifying markers of general fungal overgrowth in the gut, potentially indicating the presence of SIFO. A nutritionist may also assess SIFO based on symptoms, response to antifungal treatments, and overlapping risk factors with SIBO—such as impaired motility or immune issues.
What Causes SIBO?
A variety of factors can contribute to developing SIBO, including:
Slow Gut Motility
Conditions that slow down digestion, such as hypothyroidism (underactive thyroid), gastroparesis (delayed stomach emptying), and even diabetes, can create an environment where bacteria linger and multiply. Autoimmune conditions, Lyme disease, and mould toxicity can also affect gut motility and immune function, making the small intestine more susceptible to bacterial overgrowth.
Gastroenteritis and Post-Infectious IBS
Gastroenteritis is one of the major causes of SIBO, as the infection can disrupt gut motility. In some people, this leads to a form of IBS known as post-infectious IBS, where altered motility and bacterial imbalance persist even after the initial infection has cleared.
Chronic Use of Antibiotics
Antibiotics can disrupt the balance of gut bacteria, allowing certain types to overgrow and establish in the small intestine.
Digestive Disorders
Digestive issues like IBS, Crohn's disease, or coeliac disease may contribute to SIBO, especially when these conditions are associated with motility problems or inflammation.
Common Symptoms of SIBO and IMO
While both SIBO and IMO cause similar digestive distress, there are key distinctions in their symptoms. In both types, bloating and discomfort shortly after meals are common, as bacteria or methanogens ferment food in the small intestine. Identifying the specific type of overgrowth—whether hydrogen-dominant SIBO or methane-dominant IMO—is essential for targeted treatment, as each type requires a different approach to effectively address its unique symptoms and underlying causes.
Hydrogen-Dominant SIBO
This type typically leads to diarrhoea, bloating, and abdominal discomfort shortly after eating. Many people experience poor tolerance for certain carbohydrates, with symptoms often appearing within 30 minutes to an hour after a meal. This rapid fermentation of these foods by bacteria can produce excessive gas, resulting in abdominal distension, burping, and flatulence. Brain fog or fatigue are also common, as SIBO’s effects often extend beyond the digestive tract.
Methane-Dominant SIBO (IMO)
IMO is more commonly associated with constipation rather than diarrhoea. People with IMO often experience bloating and discomfort soon after eating, as well as gas and distension that tend to be more persistent due to slowed motility. Methane production slows down digestion, which can make weight gain or difficulty losing weight an additional challenge. Brain fog and fatigue are also frequently reported with IMO, adding to the overall impact on wellbeing.
Nutritional Therapy for SIBO
Functional Testing
To effectively manage SIBO, comprehensive testing can be crucial for pinpointing the type of overgrowth and other gut imbalances. Here are some functional tests nutritionists can order to help identify gut imbalances and tailor a treatment plan. These tests help provide a comprehensive picture of the gut environment, guiding a personalised approach to treatment.
SIBO Breath Tests
Lactulose or glucose breath tests to detect hydrogen or methane overgrowth, helping determine whether SIBO is hydrogen- or methane-dominant.
Comprehensive Stool Test
A comprehensive stool test to assess general bacterial balance and fungal overgrowth (SIFO), as well as markers of inflammation and digestive health.
Blood Tests for Nutrient Deficiencies
To identify any deficiencies that may have resulted from impaired absorption due to SIBO, such as vitamin D, B vitamins (including B12 and folate), magnesium, zinc, iron and calcium.
Dietary Interventions
Nutrition and lifestyle play a significant role in managing and treating SIBO. Instead of using restrictive diets, I focus on analysing each client’s current diet and creating a personalised plan to support gut health. This might include reducing or avoiding certain foods, such as gluten, sugar, caffeine, dairy, and processed foods, based on individual needs. I also emphasise an anti-inflammatory, whole-foods approach to nourish and restore balance in the gut, tailored to each person’s unique requirements.
Targeted Supplementation and Gut Support
Based on testing and a thorough assessment of symptoms, there are many natural solutions that can effectively support SIBO management and gut health. Herbal antimicrobials—such as oregano oil, allicin, berberine, and neem—can help reduce bacterial overgrowth while preserving the gut microbiome. Natural prokinetics can further support gut motility, helping prevent bacterial accumulation in the small intestine.
Addressing related issues like leaky gut and nutrient deficiencies is essential for effective SIBO management, as it helps restore nutrient absorption and reduce inflammation.. This approach helps improve nutrient absorption and reduces inflammation. Supporting digestion with betaine HCl and digestive enzymes enhances nutrient breakdown, ensuring the body can better absorb essential nutrients.
Additionally, activating the Migrating Motor Complex (MMC) is key to maintaining a healthy gut environment; this can be achieved by spacing meals 3-5 hours apart and avoiding frequent snacking.
Prebiotics like partially hydrolysed guar gum (PHGG) are especially helpful for methane-dominant SIBO, as they gently fuel beneficial bacteria without supporting methanogens. Later in treatment, probiotics may also be introduced to restore a balanced and resilient gut microbiome.
Lifestyle Factors
Lifestyle adjustments are crucial for preventing SIBO recurrence and supporting long-term gut health. Stress management techniques, such as meditation, yoga, and deep breathing, improve gut motility and support immune function, while regular physical activity reduces the risk of bacterial buildup by promoting motility.
Additionally, consistent meal timing and thorough chewing support enzyme production, enhancing digestion. Prioritising restful sleep is also essential, as it strengthens immune function and reduces the likelihood of digestive issues.
By addressing these lifestyle factors, we can create a supportive environment for sustainable gut health.
Ready to Take Control of Your Gut Health?
If you suspect SIBO might be driving your digestive issues, it can feel overwhelming to navigate the diagnosis and treatment options on your own. I’ve helped many clients uncover the root causes of their digestive symptoms and develop a personalised plan to manage and relieve them. Let’s work together to address what’s really behind your symptoms and create a clear, manageable path forward.
Ready to Take the Next Step?Book a FREE 30-Minute Consultation with a Registered Nutritional Therapist today to discuss how we can help you achieve better health and wellbeing. Let’s work together to create a personalised plan that meets your unique needs. |
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