Archaea · Archaeon

Methanobrevibacter smithii

Commensal The dominant gut archaeon (a separate domain of life from bacteria). It makes methane from bacterial byproducts and is enriched in constipation-predominant IBS, methane-positive SIBO, and slow transit.

Associated with these conditions

Irritable bowel syndrome (IBS) Elevated

This methane-producing archaeon is enriched in constipation-predominant IBS and linked to slower transit.

Moderate evidence

Small intestinal bacterial overgrowth (SIBO) Elevated

The driver of methane-predominant overgrowth (IMO); breath methane tracks its abundance.

Moderate evidence

Chronic constipation Elevated

Methane slows intestinal transit; methanogen load repeatedly tracks constipation severity.

Moderate evidence

Obesity Elevated

Reported in HMDAD (1 cited study).

Moderate evidence

Parkinson’s disease Associated with

Reported in Disbiome.

Preliminary

Multiple sclerosis Associated with

Reported in Disbiome.

Preliminary

Inflammatory Bowel Disease Associated with

Reported in Disbiome.

Preliminary

Anorexia Nervosa Associated with

Reported in Disbiome.

Preliminary

Bacterial Vaginosis Associated with

Reported in Disbiome.

Preliminary

Migraine Associated with

Reported in Disbiome.

Preliminary

Crohn Disease Associated with

Reported in Peryton.

Preliminary

Inflammatory bowel disease (IBD) Associated with

Reported in Peryton.

Preliminary

Parkinson Disease Associated with

Reported in Peryton.

Preliminary

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