Understanding SIBO: A Functional Medicine Approach with Peter Williams & Tracey Randall

Small Intestinal Bacterial Overgrowth (SIBO) is an often-overlooked condition that affects a significant proportion of individuals with digestive complaints.

In this episode of the Functional Medicine Bite-Size Podcast, Peter Williams welcomes his long-time colleague, Tracey Randall, an experienced IFM-certified practitioner specialising in digestive health.

Together, they explore the complexities of SIBO, its symptoms, causes, and treatment strategies. 

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What is SIBO?

SIBO occurs when bacteria, typically found in the large intestine, overgrow in the small intestine, leading to digestive distress. These bacteria ferment food particles, producing excess gas (hydrogen, methane, or hydrogen sulfide), which can lead to symptoms like bloating, abdominal discomfort, diarrhoea, constipation, and reflux.

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Why Do People Develop SIBO?

Many factors can contribute to the onset of SIBO, including:

• A history of food poisoning or traveller’s diarrhoea
• Gut motility issues and dysfunction of the migrating motor complex (MMC)
• An impaired ileocecal valve, which allows bacteria to move back into the small intestine
• Prolonged use of NSAIDs or antibiotics
• Chronic stress or a significant life event that impacts gut function
• Underlying conditions like inflammatory bowel disease (IBD) or autoimmune disorders

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Recognising the Symptoms of SIBO

If you've been experiencing digestive discomfort that hasn’t resolved, SIBO could be the underlying cause. Key symptoms include:

• Persistent bloating, especially worsening throughout the day
• Gas and belching
• Alternating constipation and diarrhoea
• Reflux and indigestion
• Brain fog and fatigue
• Unexplained nutrient deficiencies, such as low B12 and iron

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Testing for SIBO

Diagnosing SIBO is crucial for targeted treatment. The gold standard test is the hydrogen and methane breath test, which measures gas production over a three-hour period after consuming a sugar solution. In cases of hydrogen sulfide SIBO, results may appear as a ‘flat line,’ indicating an overgrowth of sulfur-reducing bacteria.

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Treatment Approaches for SIBO

Addressing SIBO requires a multi-faceted approach, as it tends to recur if underlying factors aren’t resolved.

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1. Dietary Modifications

• A low FODMAP diet can provide symptom relief by reducing fermentable carbohydrates that fuel bacterial overgrowth.
• Patients with hydrogen sulfide SIBO may need to temporarily limit sulfur-rich foods like garlic, onions, and cruciferous vegetables.
• Diet alone won’t cure SIBO but plays a vital role in managing symptoms during treatment.

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2. Antimicrobials & Antibiotics

• Herbal antimicrobials such as berberine, allicin, and neem are often used to target bacterial overgrowth.
• The antibiotic Rifaximin is a standard pharmaceutical treatment for hydrogen-dominant SIBO, while methane-dominant cases may require additional treatment with neomycin or metronidazole.
• Treatment duration varies, often requiring multiple rounds to fully resolve overgrowth.

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3. Supporting Gut Motility

• Prokinetics, such as ginger, prucalopride, and low-dose erythromycin, can help stimulate the MMC to prevent bacterial stasis.
• Addressing the gut-brain connection is essential, as stress and poor vagal nerve function can impair motility.

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4. Probiotics, Prebiotics & Postbiotics

• Emerging research suggests specific probiotic strains can support SIBO treatment, despite the previous assumption that probiotics exacerbate symptoms.
• Saccharomyces boulardii and spore-based probiotics have shown promise in clinical practice.
• Prebiotics should be introduced cautiously, as they can exacerbate symptoms in some cases.

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5. The Role of Sulfur in Gut Health

One of the more recent breakthroughs in SIBO treatment involves the use of MSM (methylsulfonylmethane) to support sulfur detox pathways. Patients with hydrogen sulfide SIBO often have difficulty metabolising sulfur, leading to dysbiosis. Some cases have shown symptom resolution with MSM supplementation, highlighting a potential shift in treatment strategies.

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Why Treating SIBO Matters

SIBO is not just a digestive issue—it has systemic implications. Left untreated, it can contribute to conditions such as:

• Autoimmune disorders
• Chronic fatigue syndrome and fibromyalgia
• Mood disorders, including anxiety and depression
• Nutrient deficiencies impacting overall health

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Final Thoughts: A Long-Term Approach

Successfully managing SIBO requires more than just clearing the overgrowth—it’s about preventing relapse. Lifestyle modifications, gut-friendly diets, and stress management play a key role in maintaining gut health post-treatment.

Want to take control of your gut health?

If you suspect you have SIBO, working with a functional medicine practitioner at FMA can help you develop a personalised approach to healing.

Book a consultation today and start your journey towards lasting relief.

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