Testing Modalities: What They Show and What They Don't
Every test is a window, not a wall map
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Lesson 2.3 · Page 1
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Learning objective: Compare the major gut-testing modalities (stool analysis, SIBO breath testing, gut permeability testing), and critically evaluate their respective strengths and limitations.
Before we begin
“A client hands you a £400 private stool microbiome report and asks “so what do I do now?””
What's your honest first response — before you've even read the results?
Watch alongside this lesson
SIBO Breath Collection: Step-by-Step Guide
Genova Diagnostics
A reputable diagnostics lab walks through how a lactulose breath test is actually collected — useful context for what the test does and doesn't capture.
Supporting video selected for this topicOpen on YouTube
Key Points
- A core evidence-based skill is knowing what a test can't tell you — not just what it measures.
- Stool analysis reflects the colon primarily, and there is no single agreed "normal" reference range across labs.
- SIBO breath testing is a useful, non-invasive screening tool — but an indirect proxy with debated thresholds.
- Permeability ("leaky gut") testing is a younger, less standardised field — one data point, never a verdict on its own.
- IgG food-sensitivity testing mainly indicates exposure, not a clinically meaningful reaction.
- No single test tells the whole story: use results as one input alongside a thorough history and timeline. Over-testing is a marker of poor practice, not thoroughness.