SIBO: A Comprehensive Guide to Diagnosis and Treatment
Small Intestinal Bacterial Overgrowth (SIBO) is an increasingly recognised digestive condition that affects thousands of people in the UK. At theEdinburgh Centre for Functional Medicine, we specialise in identifying and treating the root causes of SIBO, helping patients achieve lasting relief from uncomfortable digestive symptoms.
What Is Small Intestinal Bacterial Overgrowth?
Your large intestine naturally houses trillions of beneficial bacteria that play crucial roles in digestion, immunity, and overall health. However, when these microorganisms migrate backwards into the small intestine—where they don’t belong in large numbers—they create an imbalance known as SIBO.
The small intestine should contain relatively few bacteria compared to the colon. When bacterial populations grow excessively in this region, they begin fermenting dietary carbohydrates and sugars, producing excessive gas and triggering a cascade of digestive symptoms.
Recognising the Signs of SIBO
SIBO manifests through a variety of uncomfortable symptoms that can significantly impact quality of life:
- Persistent bloating, particularly after meals
- Excessive gas and flatulence
- Abdominal discomfort or cramping
- Alternating diarrhoea and constipation
- Belching and reflux
- Nausea
- Fatigue
- Nutrient deficiencies (iron, B12, fat-soluble vitamins)
- Unexplained weight loss
When bacterial overgrowth persists, it can damage the delicate finger-like projections (villi) lining the small intestine. These structures are essential for nutrient absorption, and their impairment often leads to deficiencies in vitamins and minerals, even when dietary intake appears adequate.
Understanding the Root Causes
At the Edinburgh Centre for Functional Medicine, we recognise that SIBO rarely occurs in isolation. It typically develops when normal digestive motility—the rhythmic muscular contractions that move food through your system—becomes compromised. When this natural “housekeeping” function slows down, bacteria have the opportunity to proliferate where they shouldn’t.
Common Contributing Factors Include:
- Structural abnormalities: Previous abdominal surgery, intestinal scarring, or diverticula
- Motility disorders: Conditions affecting the migrating motor complex (MMC), which sweeps bacteria through the digestive tract
- Low stomach acid: Reduced gastric acid production (hypochlorhydria) or use of proton pump inhibitors
- Bile insufficiency: Inadequate bile flow, which normally has antimicrobial properties
- Immune dysfunction: Compromised immune responses in the gut
- Thyroid disorders: Hypothyroidism can slow digestive transit
- Diabetes: High blood sugar can affect nerve function controlling gut motility
- Chronic stress: Prolonged stress impacts digestive function through the gut-brain axis
- Food poisoning: Post-infectious IBS can trigger SIBO development
- Medications: Antibiotics, opioids, and other drugs affecting gut flora or motility
This list represents just a fraction of the potential underlying causes. Our functional medicine approach involves investigating your unique health history to identify the specific factors driving your condition.
Accurate Testing and Diagnosis
We utilise breath testing to diagnose SIBO—a non-invasive method that measures hydrogen and methane gases produced by bacterial fermentation. The test involves consuming a sugar solution (either lactulose or glucose) and then providing breath samples at regular intervals over a three-hour period.
As bacteria ferment the sugar substrate, they produce measurable gases that appear in your breath. Elevated levels of hydrogen and/or methane indicate bacterial overgrowth in the small intestine.
Different SIBO Subtypes
SIBO is not a one-size-fits-all condition. We commonly identify three distinct patterns:
- Hydrogen-dominant SIBO: Characterised by elevated hydrogen production, often associated with diarrhoea
- Methane-dominant SIBO (IMO): Now termed Intestinal Methanogen Overgrowth, typically linked with constipation
- Hydrogen sulphide SIBO: Cannot be measured on standard breath tests but suspected based on specific symptoms like sulphur-smelling gas
Identifying your specific SIBO subtype is crucial because each requires a tailored treatment approach.
Our Treatment Philosophy
Successful SIBO treatment extends beyond simply eliminating bacteria. At the Edinburgh Centre for Functional Medicine, we focus on three essential pillars:
1. Symptom Management Through Dietary Modification
Many patients experience significant relief by temporarily reducing fermentable carbohydrates. A low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) approach can help minimise bacterial fermentation and associated symptoms.
Foods to Limit Initially:
- Certain fruits: apples, pears, watermelon, cherries, dried fruits
- High-lactose dairy: milk, soft cheeses, yoghurt
- Wheat and rye products
- Legumes: beans, lentils, chickpeas
- Certain vegetables: onions, garlic, cauliflower, mushrooms
- Sugar alcohols: sorbitol, mannitol, xylitol
However, dietary restriction alone doesn’t address the underlying bacterial imbalance or motility issues. It’s also worth noting that recent research suggests hydrogen sulphide SIBO may actually benefit from higher FODMAP intake—another reason why accurate testing is essential.
2. Addressing Bacterial Overgrowth
We employ targeted antimicrobial protocols—either pharmaceutical antibiotics or herbal antimicrobials—to reduce excessive bacterial populations. The choice depends on your SIBO subtype, medical history, and individual circumstances.
3. Preventing Relapse Through Root Cause Resolution
This is where functional medicine truly differentiates itself. SIBO has one of the highest relapse rates of any digestive condition—often because the underlying cause remains unaddressed.
Our comprehensive approach investigates and treats:
- Motility dysfunction and strategies to restore the migrating motor complex
- Stomach acid optimisation
- Bile flow support
- Thyroid function assessment and treatment
- Blood sugar regulation
- Stress management and vagal tone improvement
- Gut barrier repair and immune support
- Identification of food sensitivities or intolerances
Supporting Your Digestive Health Long-Term
While we always recommend working with a qualified practitioner to develop a personalised protocol, several general principles support digestive health:
- Eat mindfully: Chew thoroughly and avoid eating when stressed
- Space meals appropriately: Allow 4-5 hours between meals to permit the MMC to function
- Stay hydrated: Adequate water intake supports all digestive processes
- Manage stress: Chronic stress profoundly impacts gut function
- Move regularly: Physical activity promotes healthy motility
- Prioritise sleep: Quality rest is essential for gut repair and immune function
- Consider prokinetics: Under practitioner guidance, agents that stimulate motility may prevent relapse
Why Choose Functional Medicine for SIBO?
Conventional gastroenterology often focuses on bacterial eradication without addressing why the overgrowth occurred in the first place. This is why relapse rates remain frustratingly high with standard treatment approaches.
Our functional medicine practitioners at the Edinburgh Centre for Functional Medicine take a broader view. We understand that SIBO is a symptom of underlying dysfunction, not a standalone disease. By identifying and correcting the root causes—whether they involve motility issues, immune dysfunction, hormonal imbalances, or other factors—we help patients achieve lasting resolution rather than temporary relief.
Frequently Asked Questions
Can I get tested for SIBO through the NHS?
While SIBO testing isn’t routinely offered through the NHS, some gastroenterologists will arrange breath testing if you present with appropriate symptoms. However, comprehensive functional medicine investigation of underlying causes typically requires private care.
How long does SIBO treatment take?
Treatment duration varies considerably depending on your specific situation. Initial antimicrobial protocols typically last 2-4 weeks, but addressing underlying causes and preventing relapse is an ongoing process that may take several months. Most patients notice symptom improvement within the first few weeks of treatment.
Will I need to follow a restrictive diet forever?
No. Dietary restriction is a temporary tool to manage symptoms during treatment. Once we’ve addressed the bacterial overgrowth and underlying causes, most patients can gradually reintroduce foods and maintain a varied, nutritious diet.
What's the success rate for SIBO treatment?
When we address both the bacterial overgrowth and the root causes of motility dysfunction, our patients experience excellent outcomes. However, success requires commitment to the full treatment protocol and addressing lifestyle factors that may contribute to the condition.
Take the Next Step
If you’re struggling with persistent digestive symptoms that haven’t responded to conventional treatment, SIBO may be the underlying cause. At the Edinburgh Centre for Functional Medicine, our experienced practitioners specialise in comprehensive gut health assessment and personalised treatment protocols.
We offer both in-person consultations at our Harley Street location and telehealth appointments for patients throughout the UK and internationally. Our approach combines advanced functional testing with evidence-based natural therapies to help you achieve lasting digestive wellness.
Don’t let SIBO control your life. Contact us today to schedule a consultation and begin your journey toward optimal gut health.