SIBO Protocol: Systems Biology Treatment Framework

Why SIBO recurs: the missed candidate upstream mechanism

Recurrent SIBO is not a failure of prior approaches to produce durable clarity. It's a framing failure.

Most clinicians treat SIBO as a bacterial problem: bacteria overgrow, you kill them with antibiotics or botanicals, the SIBO resolves. If it recurs, you treat it again. This works for acute infections. It doesn't work for SIBO because SIBO isn't primarily a bacterial problem — it's a colonocyte bioenergetic failure that cascades into dysbiosis.

When you target bacteria without addressing the underlying energy crisis in the intestinal barrier, you're clearing the symptom while leaving the causal lesion untouched. The dysbiosis returns because the host environment — the colonocyte's mitochondrial capacity — never changed.

This is the Host Capacity Model applied to SIBO. It inverts conventional thinking by asking: why did bacteria overgrow in the first place? The answer isn't "they invaded." The answer is: your colonocytes ran out of energy.

Understanding SIBO through systems biology

The standard model (why it fails)

Conventional SIBO teaching:

1. Bacteria overgrow in the small intestine
2. They ferment carbohydrates, producing hydrogen and methane
3. These gases cause bloating, constipation, and diarrhea
4. Treat with rifaximin, herbals, or diet, and bacteria decrease
5. Symptoms resolve — until they recur

This is descriptive, not mechanistic. It describes what happens without explaining why bacteria overgrew in the first place.

The mechanistic model: colonocyte bioenergetic failure

Colonocytes are the most metabolically active epithelial cells in the body. They maintain tight junctions (claudins, ZO-1) via ATP-dependent active transport, the barrier mucus layer (goblet cell secretion requires sustained mitochondrial ATP), antimicrobial peptides (lysozyme, defensins), and healthy microbial ecology through metabolite signaling.

When mitochondrial function fails in colonocytes, all of these collapse simultaneously. The upstream cascade: CD38 upregulation from chronic inflammation depletes NAD+; Complex I/II electron transport impairment produces pseudohypoxia; SIRT3 loss-of-function from NAD+ depletion causes mitochondrial proteome acetylation chaos; Fe-S cluster biosynthesis failure (ISCU bottleneck) shuts down the electron transport chain. Net result: colonocyte ATP production drops 40–60% while energy demand remains constant.

With ATP limiting in colonocytes, claudins (especially Claudin-2) become phosphorylated and internalized, ZO-1 loses structural integrity, and tight-junction permeability increases — opening the door to LPS translocation. Goblet cell ATP depletion thins the mucus layer. Paneth cell energy deficit reduces antimicrobial peptide output. Increased permeability plus reduced microbial suppression equals dysbiosis opportunity.

Facultative anaerobes expand into the small intestine (SIBO-H₂). Sulfate-reducing bacteria (Desulfovibrio, Desulfobacter) flourish when the mucus layer thins. Methanogenic archaea (Methanobrevibacter smithii) increase in those with slower transit. The dysbiotic metabolite profile emerges: ↓ butyrate, ↑ secondary bile acids, ↑ H₂S, ↑ LPS, ↑ D-lactate.

LPS translocation binds TLR4 on lamina propria macrophages, triggering TNF-α, IL-6, and IL-1β production. This perpetuates CD38 upregulation, consuming more NAD+, closing the loop. This is why antibiotics alone fail. You break the dysbiosis temporarily, but the colonocyte energy deficit remains. The dysbiosis re-establishes within weeks to months.

The Host Capacity Model: four-phase recovery protocol

Phase 1: Bioenergetic assessment (weeks 1–2)

Identify the specific bioenergetic bottleneck driving colonocyte failure. Panel: Organic Acid Test (Krebs cycle intermediates, B-vitamin markers, oxidative stress); intracellular NAD+ panel (target >500 μM; <300 indicates severe depletion); mitochondrial markers (lactate, pyruvate/lactate ratio, carnitine, CoQ10); Fe-S cluster proxies (iron, ferritin, TIBC, B2, B3); inflammation and barrier integrity (hs-CRP, LPS/LBP, zonulin, calprotectin).

Decision tree: If NAD+ depleted plus high hs-CRP plus elevated LPS/LBP, prioritize anti-inflammatory and NAD+ restoration. If high lactate plus low carnitine with normal inflammation, prioritize mitochondrial membrane transport restoration. If low B vitamins plus elevated methylmalonic acid, add comprehensive methylation support and cofactor repletion.

Phase 2: Dysbiosis mapping (weeks 2–4)

Shotgun metagenomics for full taxonomic and functional gene profile (look for ↑ Klebsiella, ↑ Citrobacter, ↑ Desulfovibrio, ↓ Faecalibacterium, ↓ Roseburia). Quantitative SCFA panel (butyrate should be >3 mmol/kg feces). H₂S-specific markers if neurological symptoms coexist with negative or low H₂/CH₄ — standard breath tests do not measure H₂S.

Phase 3: Protocol implementation (weeks 4–12)

Antimicrobial strategy. Botanicals first (weeks 1–4): allicin extract (Allimax) 450 mg three times daily; berberine 500 mg twice daily; oil of oregano (carvacrol) 75–150 mg three times daily; bismuth subnitrate 240 mg twice daily. If inadequate response (weeks 5–8): rifaximin 550 mg twice daily for 14 days, or neomycin 500 mg twice daily for 10 days. Follow with a 3–5 day elemental diet to break dysbiotic momentum. For H₂S SIBO add molybdenum cofactor (75–150 mcg daily), zinc carnosine (150 mg twice daily), and reduced L-glutathione (500–1000 mg daily).

Dietary strategy. Weeks 4–8 restriction: low-FODMAP framework; restrict sulfur precursors (cruciferous vegetables, onions, garlic, eggs, red meat) if H₂S-dominant. Emphasize bioenergetic substrates: MCT oil (1–2 tablespoons daily), polyphenols (berries, green tea, dark chocolate), high-quality amino acids (grass-fed meat, wild fish, bone broth). Use small frequent protein feeds rather than large boluses. Weeks 8–12 reintroduction: gradually shift toward Mediterranean-style; bloating after a food signals dysbiotic recurrence.

Bioenergetic restoration. NMN 500–1000 mg daily (preferred) or NR 500–1000 mg daily, or IV NAD+ 250–500 mg weekly for 4–8 weeks if severely depleted; target intracellular NAD+ >500 μM by week 8. Sodium butyrate (enteric-coated) 1–2 g daily, or tributyrin 500–1000 mg daily, for 8–12 weeks minimum. After week 8, prebiotics: inulin 5–15 g, FOS 5–10 g, or partially hydrolyzed guar gum 5 g daily. Mitochondrial cofactors: ubiquinol 200–400 mg, B2 100–200 mg, B3 50–100 mg, L-carnitine 500–2000 mg, iron only if ferritin <50 and inflammatory markers low. Mucosal healing: L-glutamine 5–10 g, zinc carnosine 150–300 mg, bone broth 8–12 oz, slippery elm 1–2 g daily.

Phase 4: Restoration and long-term prevention (week 12+)

Retest at week 12: intracellular NAD+ (>500 μM), SIBO breath test (negative or dramatically improved), metagenomics (↑ Faecalibacterium, ↓ dysbiotic gram-negatives), barrier markers (↓ zonulin, ↓ calprotectin). Discontinue antimicrobials. Begin slow FODMAP reintroduction. Transition butyrate from pharmaceutical to food-based (resistant starch, whole grains). Continue NAD+ support indefinitely (~500 mg daily). Now introduce a multi-strain clinical-grade probiotic, starting low and titrating up.

Maintenance baseline: NMN 500 mg, resistant starch or inulin 10–20 g, polyphenol-rich foods, daily probiotics, bone broth or collagen hydrolysate. Weekly: 16–18 hour intermittent fasting once or twice; stress management (breathwork, cold exposure, meditation) to support parasympathetic tone. Monthly: reassess tolerance and watch for recurrence signals; if recurrence starts, return to Phase 3 for 4 weeks before resuming Phase 4.

Frequently asked questions

Related reading

• The Host Capacity Model
• Dysbiosis treatment framework
• MCAS stratification guide