SIBO Explained: Diagnosis and Treatment Options
Small Intestinal Bacterial Overgrowth (SIBO) is a condition that occurs when bacteria that normally live in the large intestine begin to grow excessively in the small intestine. This imbalance can interfere with nutrient absorption and cause a range of digestive symptoms, from bloating and gas to more complex gastrointestinal issues. Because SIBO often mimics other digestive disorders, it is frequently overlooked or misdiagnosed.
In this guide, we’ll break down what SIBO is, how it develops, its most common symptoms, and what current research says about effective diagnosis and treatment. Whether you're experiencing persistent bloating or navigating a chronic digestive issue, understanding SIBO can be a key step toward long-term relief and gut health.
What Is SIBO and Why Does It Happen
SIBO, or Small Intestinal Bacterial Overgrowth, is a condition in which an excessive amount of bacteria is present in the small intestine. While the large intestine is designed to host a dense population of bacteria to aid in fermentation and waste breakdown, the small intestine is meant to have relatively low bacterial levels. When this balance is disrupted and bacteria migrate or multiply in the small intestine, it can interfere with digestion and nutrient absorption.
The overgrowth often occurs when food motility slows down. In a healthy digestive system, the small intestine uses coordinated muscular contractions—known as the migrating motor complex (MMC)—to move food and bacteria into the colon. If this process is disrupted, bacteria can linger in the small intestine, ferment undigested carbohydrates, and produce gases like hydrogen or methane. This fermentation leads to uncomfortable symptoms such as bloating, cramping, gas, and altered bowel habits.
There are two common subtypes of SIBO based on the gas produced:
Hydrogen-dominant SIBO is more frequently associated with diarrhea.
Methane-dominant SIBO tends to be linked with constipation and slower gut motility.
Understanding the underlying type of SIBO is important because it can influence both symptoms and treatment strategy.
What Causes SIBO to Develop
SIBO can develop due to a variety of structural or functional issues that affect digestion and motility. Anything that slows down the natural movement of food and waste through the small intestine can create an environment where bacteria begin to accumulate and thrive.
Common Causes of SIBO Include:
Abdominal surgery or scarring: Surgeries involving the intestines can lead to adhesions or blockages that interfere with motility.
Ileocecal valve dysfunction: The valve separating the small and large intestines may fail to close properly, allowing bacteria to move backward into the small intestine.
Impaired gut motility: Conditions like diabetes, hypothyroidism, or post-infectious IBS can interfere with the migrating motor complex (MMC), which helps clear the small intestine between meals.
Food poisoning or gut infections: These can trigger long-term inflammation or damage to nerves that regulate digestive flow.
Low stomach acid (hypochlorhydria): Insufficient acid allows more bacteria to survive as food moves from the stomach into the small intestine.
Identifying the root cause is essential to successfully managing and preventing recurrence of SIBO.
Common Symptoms of SIBO
SIBO can present with a wide range of symptoms, many of which overlap with other gastrointestinal conditions like IBS or food intolerances. This overlap can make diagnosis challenging without appropriate testing.
Common SIBO Symptoms Include:
Abdominal bloating and distention
Excessive gas and belching
Constipation or diarrhea (or alternating between both)
Abdominal pain or discomfort
Fatigue and brain fog
Nutrient deficiencies (such as B12 or iron)
Unintended weight loss or difficulty gaining weight
Food sensitivities or intolerance to high-FODMAP foods
Because symptoms vary, many individuals go undiagnosed or are misdiagnosed for years before discovering SIBO as the root cause.
How SIBO Is Diagnosed
The most widely used method to diagnose SIBO is the SIBO breath test, which measures hydrogen and methane gases in your breath after consuming a sugar solution. These gases are byproducts of bacterial fermentation in the small intestine.
How Breath Testing Works:
Pre-test dietary prep: Patients follow a restricted diet for 24 to 48 hours to reduce baseline gas levels.
Fasting: A 12-hour fast is required before the test begins.
Testing process: The patient drinks a sugar solution (commonly lactulose) and submits breath samples every 15–20 minutes over a 2 to 3-hour period.
Results: Elevated hydrogen or methane levels within the first 90 minutes typically indicate SIBO.
While not perfect, breath testing is a non-invasive, accessible, and effective tool for evaluating bacterial overgrowth in the small intestine.
Treatment Options for SIBO
SIBO treatment is highly individualized and often includes a combination of dietary support, antimicrobial therapy, motility agents, and lifestyle interventions. The goal is not just to reduce bacteria, but to restore healthy gut function and prevent recurrence.
Common Treatment Approaches:
Prescription or herbal antimicrobials: Medications like rifaximin (for hydrogen-dominant SIBO) or rifaximin plus neomycin (for methane-dominant SIBO) are commonly prescribed. Herbal blends with ingredients like berberine, oregano oil, or allicin may also be used.
Elemental diet: A liquid, nutrient-dense formula that starves bacteria while nourishing the patient. Typically used in more severe or resistant cases.
Prokinetics: These support the migrating motor complex and help prevent bacteria from accumulating after treatment.
Targeted nutrition: Temporary dietary changes, such as a low-FODMAP or SIBO-specific diet, can reduce symptoms while the gut heals.
Stress and nervous system regulation: Because gut motility is closely linked to the vagus nerve, mind-body tools such as breathwork, meditation, and vagal tone exercises can support lasting relief.
Working with a healthcare provider familiar with SIBO is key to identifying the right combination of therapies for your needs.
Why Treating the Root Cause Matters
SIBO is often a symptom of an underlying dysfunction—not just a random occurrence. Treating only the bacterial overgrowth without addressing why it developed in the first place increases the likelihood of relapse.
Sustainable healing requires a deeper look into motility, digestive strength, gut integrity, and lifestyle factors. With proper diagnosis and a comprehensive plan, many patients can find long-term relief and restore optimal gut function.
Conclusion
SIBO is a complex but treatable condition that often goes unrecognized. If you're experiencing persistent bloating, irregular digestion, or food sensitivities, it’s worth exploring whether bacterial overgrowth may be contributing to your symptoms.
At SageMED, we take a root-cause approach to digestive health. Our GI specialists use advanced testing, integrative therapies, and personalized care plans to help patients find lasting relief.
Reference
Center for SIBO Testing. (2017, February 19). About hydrogen and methane breath testing. Center for SIBO Testing. Retrieved February 13, 2023, from https://centerforsibotesting.com/about-hydrogen-and-methane-breath-testing/
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