Does the GI-MAP test for SIBO?

No. SIBO is diagnosed with a hydrogen/methane breath test. The GI-MAP is a stool test that reflects the large intestine; it can flag methanogens and dysbiosis but does not diagnose SIBO.

Can a stool test replace a SIBO breath test?

No. Because SIBO is about overgrowth in the small intestine, a stool test cannot confirm it. Breath testing remains the standard, and the GI-MAP is complementary at most.

SIBO and the GI-MAP: What It Can and Cannot Show

SIBO is diagnosed with breath testing, not stool testing. Here is what the GI-MAP can and cannot tell you about bacterial and methanogen overgrowth.

Educational overview · Medically reviewed by Madison Ordway, FDN-P

Key facts

What SIBO is: excess bacteria in the small intestine (IMO is the methane form).
How it's diagnosed: breath testing (hydrogen/methane) — not stool.
GI-MAP's role: a large-intestine stool profile; it does NOT diagnose SIBO.
Where it can help: flags methanogens and dysbiosis patterns some practitioners weigh alongside breath testing.

Small intestinal bacterial overgrowth (SIBO) — and its methane-predominant form, intestinal methanogen overgrowth (IMO) — involves excess microbes in the small intestine. An important point up front: SIBO and IMO are diagnosed with breath testing, not stool testing. The GI-MAP (Gastrointestinal Microbial Assay Plus) is a stool test and does not diagnose SIBO.

Why a stool test is not a SIBO test

SIBO is fundamentally about where microbes are — too many in the small intestine. A stool sample reflects the large intestine, so it cannot confirm small-bowel overgrowth. That is why the standard tests for SIBO and IMO are hydrogen and methane breath tests, and why the GI-MAP should not be used as a substitute for them.

What the GI-MAP can still add

The GI-MAP does detect methanogenic archaea (Methanobacteriaceae) and can show broader dysbiosis patterns — shifts in the balance of gut bacteria that are studied as a general marker of gut imbalance (PMID: 32438689). Some practitioners review these findings alongside a breath test to build a fuller picture of the gut. On their own, they are context, not a SIBO diagnosis.

If SIBO or IMO is suspected, the right next step is to discuss breath testing with a qualified practitioner.

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References

Magne F, Gotteland M, Gauthier L, et al. The Firmicutes/Bacteroidetes ratio: a relevant marker of gut dysbiosis in obese patients? Nutrients. 2020;12(5):1474. PMID: 32438689.

Medically reviewed by

Madison Ordway, FDN-P

Functional Diagnostic Nutrition Practitioner specializing in gut health, hormone balance and mineral optimization. Madison uses GI-MAP testing in her work with clients and has been featured in US Insider, Women’s Journal and The Science Times. See press features →

Content reviewed against Diagnostic Solutions Laboratory documentation and peer-reviewed literature. Last reviewed 6 July 2026.

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