SIBO
Functional Medicine Gold Coast
wave functional health
Dr Matt le Roux
Small Intestinal Bacterial Overgrowth is one of the most common and consistently missed drivers of chronic bloating, IBS, and digestive dysfunction.
A Diagnosis That Hides in Plain Sight
Bloating That Begins Immediately After Eating and Never Fully Resolves
An important note. Functional medicine does not replace specialist care, prescribed medication, or medical monitoring. It can help identify modifiable factors that may influence inflammation, immune resilience, symptom burden, flare frequency, and quality of life - alongside your existing medical team.
You may have tried every elimination diet available — removed gluten, dairy, FODMAPs, and more — and still found yourself bloated within thirty minutes of a meal that should have been perfectly safe. The symptoms are so consistent and so predictable that you have started planning your life around them.
What has likely not been investigated is whether bacteria have colonised the part of your digestive system where they should not be, and are fermenting the food you eat before it can be properly absorbed.
SIBO — small intestinal bacterial overgrowth — occurs when bacteria migrate into or fail to be cleared from the small intestine, where bacterial populations should be very low. These bacteria ferment carbohydrates early in the digestive process, producing gas and triggering an immune response that explains the bloating, discomfort, and systemic symptoms that follow meals.
It is not a sensitivity to the food. It is a structural problem in the gut environment. And it requires a different approach to the one that treats the symptom rather than the cause.
You have tried everything.
The bloating keeps coming back.
The Gap in Standard Care
Why SIBO Is So Often Missed by Conventional Medicine
SIBO is not part of a standard gastroenterological workup. A colonoscopy assesses the large intestine. An endoscopy assesses the upper stomach and oesophagus. The small intestine, which is where SIBO occurs, is largely inaccessible through standard endoscopic procedures and is not routinely cultured or tested.
Most patients with SIBO receive an IBS diagnosis and are advised to follow a low-FODMAP diet, which can reduce symptoms but does not address the bacterial overgrowth itself. Without eradicating the overgrowth, symptoms persist or return whenever dietary restrictions are relaxed.
Even when SIBO is suspected, the hydrogen breath test offered in standard care is often not sensitive to methane-producing organisms, which represent a distinct and very common pattern of SIBO that produces constipation-predominant symptoms. The result is that a significant proportion of patients with methane SIBO receive a negative test result and are effectively dismissed despite ongoing and significant digestive symptoms.
What We Look For
What Drives SIBO and Why It Keeps Coming Back
The small intestine is designed to be a relatively low-bacteria environment. It is kept that way by several protective mechanisms: the migrating motor complex, which sweeps the small intestine clean between meals; gastric acid, which kills ingested bacteria before they reach the small intestine; the ileocecal valve, which prevents backflow of bacteria from the large intestine; and the immune tissues lining the gut wall. When any of these mechanisms fail, bacteria migrate upward from the large intestine or are not adequately cleared from the small intestine after a meal, leading to overgrowth.
Common triggers include prior food poisoning or gastroenteritis, which can damage the nerve cells controlling the migrating motor complex; chronic stress, which slows motility and reduces gastric acid output; proton pump inhibitor use, which reduces the acid barrier; hypothyroidism, which slows gut transit systemically; and structural issues including adhesions from abdominal surgery. Identifying the predisposing factors is as important as treating the overgrowth itself, because SIBO has a high recurrence rate when the underlying drivers are not addressed.
At Wave Functional Health we assess not just whether SIBO is present but the type of gas-producing organisms involved, the state of the broader gut ecosystem through comprehensive microbiome testing, the motility mechanisms through clinical history and functional markers, and the systemic factors including thyroid function, cortisol patterning, and nutritional status that affect gut integrity and immune defence. This gives us a complete picture of both the overgrowth and the conditions that allowed it to develop.
Our Approach
How Wave Functional Health Tests and Treats SIBO
We use lactulose or glucose breath testing to identify hydrogen and methane gas production patterns consistent with SIBO, alongside comprehensive stool analysis through GI MAP or Nutripath MicrobiomiX to assess the broader gut microbiome context.
Blood chemistry through OptimalDX identifies nutrient depletions, particularly fat-soluble vitamins A, D, E, and K, B12, and iron, that commonly result from malabsorption driven by SIBO. Thyroid function and cortisol patterns are assessed where indicated as systemic contributors to impaired gut motility.
Treatment is sequenced based on what the testing shows. We do not treat SIBO with a generic protocol because the type of overgrowth, the underlying drivers, and the broader gut environment all influence which approach will be most effective.
Frequency Specific Microcurrent can be used to support gut motility and vagal nerve tone as part of the recovery protocol.
Test and identify the gas pattern
Breath testing measuring both hydrogen and methane identifies whether hydrogen-dominant, methane-dominant, or mixed SIBO is present — each with different clinical implications for treatment.
Assess the broader gut ecosystem
Stool testing via GI MAP or MicrobiomiX assesses the large intestinal microbiome, digestive markers, and immune function — providing the full gut context beyond the SIBO finding alone.
Address the overgrowth directly
Targeted antimicrobial or herbal protocols are selected based on the specific gas pattern and patient history. Dietary management supports treatment but does not replace it.
Repair the intestinal lining
Once the overgrowth is addressed, mucosal lining repair, immune support, and microbiome restoration are sequenced to rebuild gut integrity and reduce reactivity.
Address the underlying drivers
Motility support, thyroid assessment, stress physiology, and dietary reintroduction guidance address the conditions that allowed SIBO to develop — reducing the high recurrence rate when these factors are left unaddressed.
Monitor and adjust throughout
Retesting confirms eradication and guides the transition into the repair and prevention phases. Treatment response is monitored clinically and adjusted at each review point.
Common Presentations
SIBO symptoms are often attributed to IBS, food intolerance, or stress. The pattern of timing — particularly the rapid onset after eating and the worsening with fibre and fermented foods — is a clinically useful distinguishing feature.
Symptoms Patients Commonly Present With
Advanced Diagnostics
← Scroll to see full table
| Test | What it reveals |
|---|---|
| SIBO Breath Test (Lactulose or Glucose) | Hydrogen and methane gas production over 120 to 180 minutes, identifying hydrogen-dominant, methane-dominant, or mixed SIBO patterns with direct clinical implications for treatment selection |
| GI MAP (Diagnostic Solutions) | Quantitative PCR stool analysis assessing the large intestinal microbiome, digestive markers including pancreatic elastase, and intestinal immune markers — essential context for the full gut picture beyond the SIBO finding alone |
| Nutripath MicrobiomiX Metagenomics | Comprehensive shotgun sequencing of the gut microbiome identifying the full bacterial, fungal, and parasitic landscape alongside functional pathway analysis and metabolic capacity |
| OptimalDX Blood Chemistry | Nutrient status markers commonly depleted in SIBO including B12, iron, ferritin, vitamin D, and fat-soluble vitamins — alongside liver function and inflammatory markers assessed at functional reference ranges |
| Full Thyroid Panel | Hypothyroidism is a significant and common driver of the reduced gut motility that predisposes to SIBO. A full panel including TSH, free T3, free T4, and antibodies identifies thyroid-mediated contributions to recurrence |
| Organic Acids Testing | Fermentation byproducts from small intestinal bacteria including D-lactate and arabinose that confirm bacterial and fungal overgrowth patterns at the metabolic level and provide additional diagnostic specificity |
| Cortisol and HPA axis assessment | Chronic stress reduces gastric acid output, impairs gut motility, and increases intestinal permeability — three mechanisms that directly predispose to SIBO development and recurrence |
Testing we use to investigate SIBO
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Common drivers we investigate
Who This Is For
This approach may suit you if...
SIBO is worth investigating whenever the clinical picture involves chronic bloating, digestive symptoms that have not resolved with dietary changes, and a history of IBS diagnosis without meaningful improvement.
You do not need a confirmed SIBO diagnosis to begin an investigation. If the symptom pattern suggests bacterial overgrowth as a plausible explanation for what you are experiencing, that is sufficient reason to look more closely.
Frequently Asked Questions
What people ask about SIBO care at Wave
Hydrogen-dominant SIBO involves bacteria in the small intestine producing hydrogen gas as they ferment carbohydrates. It typically presents with bloating, diarrhoea, and cramping. Methane-dominant SIBO, more accurately called intestinal methanogen overgrowth, involves archaea producing methane gas, and is strongly associated with constipation and slower gut transit.
The two patterns often require different treatment approaches, which is why breath testing that measures both gases is important for directing the right protocol.
A low-FODMAP diet reduces the fermentable substrate available to bacteria in the small intestine and can significantly reduce symptoms, but it does not eliminate the overgrowth. As soon as FODMAP-containing foods are reintroduced, the bacteria that remain in the small intestine will begin fermenting them again and symptoms will return.
Dietary management is a useful tool for symptom control during treatment, but the overgrowth itself requires direct antimicrobial intervention followed by strategies to prevent recurrence.
Yes, and this is a significant and underappreciated consequence of untreated SIBO. Bacteria in the small intestine compete with the host for nutrients, particularly B12 and iron. They also damage the brush border of the intestinal lining, reducing the enzyme capacity needed to absorb carbohydrates, fats, and fat-soluble vitamins including vitamins A, D, E, and K.
Iron deficiency anaemia that does not respond to oral iron supplementation is a clinical red flag for SIBO in the absence of obvious blood loss.
SIBO recurs when the underlying conditions that allowed it to develop in the first place are not addressed. The most common reasons for recurrence include impaired motility from a damaged migrating motor complex following gastroenteritis, ongoing hypothyroidism reducing gut transit, continued use of proton pump inhibitors reducing the acid barrier, structural issues such as adhesions, or insufficient repair of the intestinal environment after treatment.
At Wave, identifying and correcting the predisposing factor is a central part of the SIBO treatment approach rather than an afterthought.
Probiotic use in active SIBO is nuanced and depends on the type of organisms involved, the clinical picture, and the phase of treatment. In some patients probiotics can worsen symptoms by adding to the bacterial load in the small intestine. In others, specific Lactobacillus and Bifidobacterium strains can be beneficial, particularly in the post-treatment phase.
We assess this individually based on your test results and clinical history rather than applying a general recommendation that may not suit your specific presentation.
Your bloating has a cause.
And that cause can be investigated.
The problem is not what you are eating. It is what is happening to the food before it can be absorbed. At Wave Functional Health, Dr Matt tests for SIBO directly, identifies the type and the drivers, and builds a treatment plan that addresses both the overgrowth and the conditions that created it.
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