Understanding SIBO: Why Personalized Nutrition Matters
Small Intestinal Bacterial Overgrowth (SIBO) occurs when excessive bacteria accumulate in the small intestine, which normally contains relatively few microbes. When this balance shifts, bacteria ferment food earlier than they should, producing gas and byproducts that lead to symptoms such as bloating, gas, abdominal pain, diarrhea, constipation, nausea, and early fullness.¹
SIBO presents differently depending on the type of gas produced. Hydrogen-dominant SIBO is typically linked to diarrhea, cramping, and rapid gas production, while methane-dominant SIBO (also called intestinal methanogen overgrowth, or IMO) is often associated with constipation, harder stools, and abdominal pressure. Some people have mixed SIBO, showing features of both types.² These differences influence symptoms, treatment, and nutrition strategies, making personalized care essential.
What Causes SIBO?
SIBO develops when normal digestive function is disrupted. Common contributing factors include impaired gut motility, structural changes or prior surgeries, long-term acid suppression, and coexisting digestive or systemic conditions like IBS, celiac disease, diabetes, or connective tissue disorders.³⁻⁴ Because these factors interact differently in each person, SIBO rarely looks the same from one individual to another.
How SIBO Is Diagnosed
SIBO is most often diagnosed using a lactulose or glucose breath test, which measures hydrogen and methane gas production after a carbohydrate drink is consumed. Early rises in gas suggest fermentation in the small intestine.¹ Breath tests are noninvasive and widely used, though results can be influenced by rapid transit or preparation errors, so interpretation by a clinician is important.⁵
Treatment Approaches
Managing SIBO usually involves a combination of strategies:
Antibiotics or antimicrobial therapy: Rifaximin is common for hydrogen-dominant SIBO; methane-dominant cases may require combination therapy.⁴
Motility support: Lifestyle adjustments, prokinetics, and meal spacing help reduce recurrence.³
Addressing underlying causes: Medication adjustments, correction of structural issues, and management of coexisting conditions support long-term success.¹
Nutrition therapy: Diet alone does not cure SIBO, but personalized nutrition can reduce symptoms, support tolerance, and enhance overall digestive health.²,⁶
The Role of Personalized Nutrition
Because SIBO varies by subtype, symptoms, and underlying causes, nutrition therapy should be tailored to the individual. A dietitian can help by:
Adjusting food choices based on symptom patterns and gas type
Supporting nutrient intake and addressing deficiencies²
Guiding gradual reintroduction of foods to restore variety and support the microbiome⁶
Coordinating diet with meal timing, fiber type, and hydration to support motility³
Personalized nutrition is most effective when integrated with medical therapy and other SIBO management strategies.
Takeaway
SIBO is a complex condition with diverse causes and symptoms. A personalized approach — including medical treatment, motility support, and nutrition guidance — provides the best chance for symptom relief and long-term improvement. If you’re experiencing bloating, irregular bowel habits, or other digestive issues, our dietitians can help you understand your symptoms and create a plan tailored to your body’s needs. Schedule an appointment today to start your personalized digestive health plan.
References
StatPearls. Small Intestinal Bacterial Overgrowth. Treasure Island (FL): StatPearls Publishing; 2025.
Wielgosz-Grochowska JP, Domanski N, Drywień ME. Identification of SIBO Subtypes along with Nutritional Status and Diet as Key Elements of SIBO Therapy. Int J Mol Sci. 2024;25(13):7341.
The importance of food quality, gut motility, and microbiome in SIBO development and treatment. Nutrition. 2024;124:112464.
Rezaie A, et al. How to Recognize and Treat Small Intestinal Bacterial Overgrowth? J Clin Med. 2022;11(20):6017.
Shah SC, Day LW. Small Intestinal Bacterial Overgrowth: Current State of the Evidence. Curr Opin Gastroenterol. 2023;39(6):527-535.
Velasco-Aburto S, et al. Nutritional Approach to Small Intestinal Bacterial Overgrowth: A Narrative Review. Nutrients. 2025;17(9):1410.
Written by Martin Aldrich, MS, RD, LN
Martin specializes in: Sports nutrition, men’s health, nutrition for aging adults, digestive concerns including IBS and navigating the FODMAP diet, general wellness, and supporting men navigating disordered eating patterns.