SIBO Diet Guide: What to Eat and Avoid When You Have Small Intestinal Bacterial Overgrowth
SIBO Diet Guide: What to Eat and Avoid When You Have Small Intestinal Bacterial Overgrowth
By Dr. Onikepe Adegbola, MD PhD — Johns Hopkins-trained physician-scientist and founder of Casa de Sante
Key Takeaways
- SIBO is bacterial overgrowth in the small intestine — dietary management starves these bacteria of fuel while keeping YOU nourished
- The low FODMAP diet is the most commonly recommended dietary approach for SIBO symptom management
- The Elemental Diet (a liquid formula) is a proven SIBO treatment — 80-85% effective at clearing SIBO in 2 weeks (this is a medical intervention, not a long-term diet)
- Meal spacing is CRITICAL for SIBO: 4-5 hours between meals allows the migrating motor complex (MMC) to sweep bacteria out of the small intestine
- Diet alone does not cure SIBO in most cases — it manages symptoms. Antibiotics (rifaximin) or herbal antimicrobials treat the overgrowth itself.
Understanding SIBO and Diet
Why Diet Matters
The bacteria causing SIBO thrive on carbohydrates — particularly fermentable carbohydrates (FODMAPs). When you eat high-FODMAP foods, these bacteria ferment them in the small intestine (where they should NOT be), producing hydrogen and/or methane gas. This causes bloating, pain, distension, diarrhea (hydrogen-dominant) or constipation (methane-dominant).
Types of SIBO
- Hydrogen-dominant SIBO: Produces hydrogen gas. Typically causes diarrhea, urgency, and cramping.
- Methane-dominant SIBO (IMO): Produces methane. Causes constipation, bloating, and distension. Methane slows gut motility.
- Hydrogen sulfide-dominant: Produces hydrogen sulfide gas. Causes diarrhea, foul-smelling gas, and systemic symptoms. Hardest to diagnose.
The SIBO Diet Strategy
Phase 1: Reduce Fermentable Substrates (Low FODMAP)
Foods to eat freely:
- Proteins: chicken, turkey, fish, eggs, beef, pork, tofu (firm)
- Fats: olive oil, coconut oil, butter, garlic-infused oil
- Low FODMAP vegetables: carrots, zucchini, bell peppers, spinach, kale, green beans, potatoes, tomatoes
- Low FODMAP fruits: strawberries, blueberries, oranges, grapes, kiwi, firm bananas
- Grains: rice, oats (small portion), quinoa, GF bread/pasta
Foods to avoid:
- Garlic and onion (all forms)
- Beans, lentils, chickpeas
- Wheat in large amounts
- Dairy (lactose-containing): milk, ice cream, soft cheese
- High fructose fruits: apples, pears, mango, watermelon
- Sugar alcohols: sorbitol, mannitol, xylitol (found in sugar-free products)
- Inulin, FOS, chicory root (found in many "health" bars and supplements)
Phase 2: Meal Spacing
This is unique to SIBO and often overlooked. Space meals 4-5 hours apart with NO snacking between meals. The MMC cycle takes 90 minutes and only runs during fasting. You need at least 2-3 complete MMC cycles between meals to keep the small intestine clear.
Phase 3: Treatment Support
During antibiotic treatment (rifaximin for hydrogen SIBO, rifaximin + neomycin or rifaximin + metronidazole for methane), some practitioners recommend BRIEFLY increasing fermentable carbohydrates to "feed" the bacteria and make them more susceptible to the antibiotic. This is called the "feed and treat" approach. Discuss with your gastroenterologist.
After SIBO Treatment
Clearing SIBO does not prevent recurrence. SIBO recurs in 40-50% of patients within 9-12 months. Long-term prevention strategies:
- Prokinetic agents (prescription: low-dose erythromycin or prucalopride) to support MMC function
- Continued meal spacing (minimum 4 hours between meals)
- Address the underlying cause (adhesions, motility disorders, structural issues)
- Ongoing digestive enzyme support to reduce undigested food reaching the small intestine
🛒 SIBO Management Support
- Digestive Enzymes — Critical for SIBO. Complete digestion in the stomach and upper small intestine means less undigested food available for bacteria to ferment. Reduces symptoms during and after treatment.
- Regularity Companion — Supports motility, especially important for methane-dominant SIBO/IMO where constipation is the primary symptom
- Daily Vitamin — SIBO causes malabsorption of B12, iron, fat-soluble vitamins (A, D, E, K), and zinc. Replenish what SIBO depletes.
Medical Disclaimer: This article is for educational purposes only. SIBO diagnosis requires breath testing and treatment requires medical supervision. Do not self-treat with antibiotics. Dr. Adegbola is the founder of Casa de Sante.
