Managing SIBO Through Dietary Interventions

By Kara Fitzgerald, ND, IFMCP, and Lara Zakaria, RPh, MSc, CNS, CDN, IFMCP.

SIBO Basics

Awareness of small intestinal bacterial overgrowth (SIBO) has increased in recent years, in part as relatively common risk factors have become more widely recognized. For instance, low stomach acid (including from PPI use), pancreatic insufficiency, irritable bowel syndrome (IBS) and Crohn’s, celiac diagnosis, and diabetes all raise the risk of SIBO.^1-3

Despite its prevalence, SIBO can be challenging to diagnose. SIBO sufferers often describe a range of agonizing gastrointestinal (GI) symptoms, including:^4,5

• Abdominal distension
• Flatulence
• Cramping
• Diarrhea 
• Constipation

Non-GI symptoms attributed to SIBO include systemic symptoms like brain fog, headaches, fatigue, skin conditions, and joint pain.^5-8

Interventions focus on the primary pathophysiology, which includes dysbiosis, altered GI motility, hypochlorhydria, reduced production of digestive enzymes, osmotic pressure, fermentation, and nutrient depletion due to malabsorption and maldigestion along with altered local and/or systemic immunity and intestinal permeability.^4,5,9,10

The mainstay of SIBO treatment is antimicrobial therapy (prescriptive and herbal),^4,11 although recurrence of infection may be common.⁵ Additionally, used solo, antibiotics are insufficient for addressing the full spectrum of underlying pathologies.^9,12,13

(Video Time: 2 minutes) In this video, Patrick Hanaway, MD, IFM educator and senior advisor to IFM’s CEO, discusses possible nutritional approaches in personalized SIBO treatment strategies. Dr. Hanaway is a board-certified family physician who teaches the clinical application of nutritional biochemistry, with an emphasis on digestion, immunology, mitochondrial function, and wellness. He is also the former medical director of the Center for Functional Medicine at the Cleveland Clinic.

Elimination Diet and Other Nutritional Considerations

In our clinic, we emphasize safe, nutrient-dense therapeutic foods with anti-inflammatory, antioxidant, and phytonutrient properties. An elimination diet can remove problematic foods contributing to local inflammation while reducing FODMAPs, starches, and sugars, which may aggravate GI symptoms.⁹ 

In the context of an elimination diet, specific foods can help these patients. Therapeutically beneficial healthy fats should be leveraged, including medium-chain triglycerides (MCTs), omega-3 sources, and butyric-acid and vitamin A–rich ghee. Bone broth is rich in L-glutamine and can help satiate and provide added minerals and collagen support to heal hyperpermeability.^14,15 Due to the nature of the pathophysiology, supplementation is usually necessary to enhance micro/macronutrient status,⁴ and we often use the following: 

• Digestive enzymes
• Betaine HCL titration
• A multivitamin with attention to fat-soluble vitamins and B12

Ideally, nutrient supplementation is informed by advanced nutrient testing to cover any nutritional gaps.

Certain prebiotic sources may be helpful;¹⁶ however, tolerance varies. Therefore, we implement prebiotics cautiously as they may contribute to GI distress, activation of inflammatory response, and non-compliance.⁷ For the same reasons, fermented foods and probiotics are generally not tolerated.⁷ Fructooligosaccharides (FOS) and inulin are common prebiotics that are not well-tolerated, but low-FODMAP fruits, vegetables, and sources of hydrolyzed guar gum or psyllium are better tolerated and contribute to improving antimicrobial efficacy.^17,18

Migrating Motor Complex Support

Support of the migrating motor complex (MMC) is essential; therefore, it’s important to integrate mindful eating, careful chewing, meditation, and pre-meal breathing and gratitude practice. Additionally, singing and gargling exercises have been shown to support MMC activation.^19,20

Meal timing strategies can be leveraged to ameliorate GI discomfort. Meal spacing and intermittent fasting might be beneficial for some with slow bowel motility.^21,22 Furthermore, therapeutic herbs such as Swedish bitters, bitter greens, ginger, and fennel seeds might also be useful.^23,24

Final Considerations

Due to the complexity and risk for nutritional inadequacy, the elimination diet should be followed under careful supervision of a nutritionist.⁹ Furthermore, this should be considered a temporary intervention meant to be followed by a careful reintroduction as soon as is safely tolerated to diversify the diet and to prevent unnecessary restriction and potential hyperreactivity. Symptom tracking during the process of careful challenge can help the clinician evaluate protocol success and guide on next steps in treatment. 

Finally, in refractory SIBO cases, using an elemental diet alone, or with a few carefully selected, well-tolerated foods may be useful as a first step or for periodic intervention.²⁵ In our clinic, we have noted a rise in the number of patients presenting with SIBO who have failed antibiotic monotherapy or suffer from relapse as a result. Augmenting antibiotic therapy with a nutrition strategy that addresses all underlying pathologies can greatly improve results, prevent recurrence, and restore health.