Gut Dysbiosis / SIBO
1. Root Cause Overview
Gut dysbiosis refers to a pathological imbalance in the composition, diversity, or metabolic activity of the intestinal microbiome. Small intestinal bacterial overgrowth (SIBO) is a specific form where colonic-type bacteria colonise the small intestine in excess, causing fermentation, malabsorption, and systemic immune activation. Both conditions disrupt the gut-immune-brain axis and are implicated in IBS, IBD, autoimmunity, mood disorders, and metabolic dysfunction. Key drivers include antibiotic overuse, proton pump inhibitor use, poor dietary fibre intake, chronic stress, and impaired motility.
2. Common Signs & Symptoms
- Bloating, particularly after meals or carbohydrate intake
- Excessive flatulence, belching
- Alternating diarrhoea and constipation (IBS pattern)
- Abdominal cramping and discomfort
- Nutrient deficiencies (B12, iron, fat-soluble vitamins)
- Brain fog and cognitive impairment
- Skin conditions: rosacea, eczema, acne
- Food intolerances (multiple, worsening over time)
- Fatigue and low energy
- Recurrent yeast infections or oral thrush
3. Labs to Consider
CBC/CMP, ferritin/B12/vitamin D, stool testing when indicated, lactulose or glucose breath test for SIBO, celiac serology when appropriate.
Choose the lab option based on what you want to assess within this root cause.
GI-MAP
Diagnostic Solutions
4. Clinical Priorities
Confirm SIBO with appropriate testing before initiating antimicrobial protocols, and assess for contributors such as impaired motility, hypochlorhydria, prior infections, adhesions, medication effects, constipation, or structural issues. Use a phased approach: reduce bacterial load, support gut lining integrity, reintroduce beneficial flora as tolerated, and maintain progress with diet and lifestyle. Avoid prolonged antimicrobial use without reassessment.
Where to Start: Top 2 Supplements
The single most evidence-backed probiotic for dysbiosis and SIBO. Antibiotic-resistant (safe to use alongside antimicrobial protocols), reduces pathogen load, restores sIgA, and protects the gut barrier. Start here before adding bacteria-based probiotics.
Broad-spectrum antimicrobial with the strongest evidence base among herbal agents for SIBO and dysbiosis. Simultaneously addresses pathogen overgrowth, reduces gut inflammation, and improves microbiome balance. Comparable to metronidazole in some studies.
5. Diet Strategy
During active dysbiosis/SIBO: consider a low-FODMAP diet (4–6 weeks) to reduce fermentable substrate. Emphasise easily digestible proteins and cooked vegetables. Avoid raw garlic, onions, legumes, and high-sugar foods during treatment phase. After treatment: gradually reintroduce prebiotic fibres and fermented foods (kefir, sauerkraut, kimchi) to rebuild microbiome diversity. Chew food thoroughly; avoid eating under stress.
6. Lifestyle Strategy
Optimise the migrating motor complex (MMC) by spacing meals 4–5 hours apart and avoiding snacking. Manage stress actively — the gut-brain axis is bidirectional and stress directly alters microbiome composition. Regular moderate exercise improves gut motility and microbiome diversity. Avoid unnecessary antibiotics and PPIs when possible. Address sleep quality — circadian disruption impairs gut barrier function.
7. Supplement Strategy
Full supplement list below. See Section 4 (Clinical Priorities) for the recommended Top 2 starting supplements. Add additional supplements based on lab results and clinical response at 4–6 week reassessment.
| Supplement | Dosage | Indication | Evidence | Key Results | Example |
|---|---|---|---|---|---|
| Saccharomyces boulardii [1] Generally well tolerated; avoid in immunocompromised patients or those with central venous catheters | 5–10 billion CFU/day during and after antibiotic/antimicrobial treatment | Prevention of antibiotic-associated dysbiosis; Clostridioides difficile protection; gut immune support | Systematic review of RCTs | Significant reduction in antibiotic-associated diarrhoea and C. difficile recurrence; improved gut barrier markers | Jarrow Formulas Saccharomyces Boulardii + MOS |
| Berberine [2] GI upset, constipation; contraindicated in pregnancy; may interact with CYP3A4 substrates | 500 mg TID (with meals) | Antimicrobial activity against SIBO-associated pathogens; gut microbiome rebalancing | RCT and in vitro studies | Significant reduction in pathogenic bacteria; improved IBS symptom scores; anti-inflammatory effects on gut mucosa | Thorne Berberine-500 |
| Oregano Oil (Origanum vulgare) [3] GI irritation; avoid in pregnancy; may alter gut flora broadly — use short-term with probiotic support | 200 mg standardised extract (≥55% carvacrol) BID | Broad-spectrum antimicrobial; SIBO and pathogen eradication support | In vitro and clinical studies | Effective against multiple GI pathogens including E. coli, Klebsiella, Candida; reduced SIBO-related symptoms | Nutricology Oregano Oil |
| Lactobacillus acidophilus + Bifidobacterium blend [4] Transient bloating during first 1–2 weeks; avoid in immunocompromised without physician oversight | 10–50 billion CFU/day (multi-strain) | Microbiome restoration post-antimicrobial treatment; barrier function support | Meta-analysis of RCTs | Significant improvement in IBS symptoms, stool consistency, and gut permeability markers | Klaire Labs Ther-Biotic Complete |
| Bacillus clausii [5] Well tolerated; rare allergic reactions | 2 billion spores TID | Spore-forming probiotic; antibiotic-resistant; SIBO and dysbiosis adjunct | RCT | Reduced duration of acute diarrhoea; improved gut microbiome recovery post-antibiotic treatment | Enterogermina (Sanofi) |
| Garlic Extract (Allicin-standardised) [6] GI upset, halitosis; anticoagulant interaction — caution with warfarin | 600–900 mg/day standardised to allicin | H. pylori eradication support; broad antimicrobial activity | Clinical and in vitro studies | Inhibited H. pylori growth; reduced pathogenic bacterial load in GI tract | Allimax 180 mg Allisure Powder |
8. Safety Notes
Do not initiate antimicrobial protocols without confirmatory testing (breath test, stool PCR). Herbal antimicrobials can disrupt beneficial flora — always pair with probiotic support and follow with a re-inoculation phase. Refer for persistent symptoms, unexplained weight loss, rectal bleeding, or positive red-flag findings. SIBO frequently recurs without addressing the underlying motility or structural cause.
9. Citations & References
- [1]Saccharomyces boulardiiMcFarland LV. Systematic review and meta-analysis of Saccharomyces boulardii in adult patients. World J Gastroenterol. 2010;16(18):2202–2222.View source
- [2]BerberineImenshahidi M, Hosseinzadeh H. Berberis vulgaris and berberine: an update review. Phytother Res. 2016;30(11):1745–1764.View source
- [3]Oregano Oil (Origanum vulgare)Force M, Sparks WS, Ronzio RA. Inhibition of enteric parasites by emulsified oil of oregano in vivo. Phytother Res. 2000;14(3):213–214.View source
- [4]Lactobacillus acidophilus + Bifidobacterium blendFord AC, Quigley EMM, Lacy BE, et al. Efficacy of prebiotics, probiotics, and synbiotics in irritable bowel syndrome and chronic idiopathic constipation: systematic review and meta-analysis. Am J Gastroenterol. 2014;109(10):1547–1561.View source
- [5]Bacillus clausiiUrdaci MC, Bressollier P, Pinchuk I. Bacillus clausii probiotic strains: antimicrobial and immunomodulatory activities. J Clin Gastroenterol. 2004;38(6 Suppl):S86–S90.View source
- [6]Garlic Extract (Allicin-standardised)Soffar SA, Mokhtar GM. Evaluation of the antiparasitic effect of aqueous garlic (Allium sativum) extract in hymenolepiasis nana and giardiasis. J Egypt Soc Parasitol. 1991;21(2):497–502.View source
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