Methane-Dominant SIBO and IMO 6-Week Food Protocol
Methane-dominant SIBO, now formally called Intestinal Methanogen Overgrowth (IMO), is one of the most common findings on a stool test for people with chronic constipation, slow transit, and bloating that worsens through the day. The driver is Methanobrevibacter smithii, an archaeon (not a bacterium) that produces methane gas by combining hydrogen with carbon dioxide. Methane gas directly slows the smooth muscle of the small bowel, which is why a single marker on a stool test can drive symptoms that feel structural. This 6-week protocol works in three phases. Phase 1 reduces the substrate methanogens depend on by introducing partially hydrolyzed guar gum and antimicrobial herbs. Phase 2 ramps the antimicrobial pressure with oregano oil and concentrated polyphenols. Phase 3 establishes a maintenance plan that prevents regrowth without permanent antimicrobial use. Most people see motility improvements within 2 to 3 weeks. The full microbiome reset typically takes the full 6 weeks plus 8 to 12 weeks of post-protocol stabilization.
Who this protocol is for
Adults with chronic constipation, abdominal bloating that worsens through the day, methane breath on a SIBO breath test, or elevated Methanobrevibacter smithii on a GI-MAP, Genova GI-Effects, or Biomesight report.
What to expect, week by week
- 1 Week 1 to 2: Less daily bloating, slightly easier bowel movements, possible mild herxheimer (die-off) reactions in the first 5 to 7 days.
- 2 Week 3 to 4: Noticeable transit time improvement. Most people report a normal daily bowel movement by week 4.
- 3 Week 5 to 6: Symptom stabilization. Bloating after meals reduces significantly. Energy improves as fermentation pressure drops.
- 4 Post-protocol: 8 to 12 weeks of maintenance is critical. Methanogens regrow easily without sustained motility support.
The 6-week food plan
Built from the protocol for Methanobrevibacter smithii, the primary marker behind this condition. Phase 1 is partially visible. The full plan with exact quantities unlocks when you upload your stool test PDF.
- Partially hydrolyzed guar gum (PHGG) See your personalized dose
- Peppermint oil capsules See your personalized dose
Unlock the full personalized version
This is the off-the-shelf protocol for Methane SIBO protocol. Upload your stool test PDF and we will build the version that handles your specific marker pattern (most people have 4 to 7 abnormal markers, not just one), with conflicts resolved and a grocery list ready to send to Instacart or Kroger.
Upload my lab PDFThe markers behind this protocol
The primary driver is Methanobrevibacter smithii. Click through for what the result means in detail. Supporting markers below often co-occur and inform the full protocol.
Common mistakes practitioners see
- Stopping at Week 2 because symptoms improve. The microbiome reset has not happened yet.
- Skipping the migrating motor complex spacing (4-hour gaps between meals). Constant snacking defeats the protocol.
- Using probiotics with high lactobacillus counts in Phase 1 (can worsen methane production initially).
- Treating with antibiotics alone without the dietary component. Recurrence rates exceed 50 percent.
When to escalate
- No bowel movement at all for more than 5 days despite the protocol.
- Severe abdominal pain (not just pressure or bloating).
- Vomiting or inability to keep food down.
- Unintended weight loss greater than 5 percent of body weight.
These signs mean stop the protocol and see a clinician. The protocol is not designed to manage acute or severe disease.
