What is SIBO? Causes, Symptoms, and How to Finally Treat It

Small Intestinal Bacterial Overgrowth, or SIBO, occurs when bacteria that normally live in your large intestine migrate and multiply in your small intestine, where they don’t belong. Even beneficial bacteria can cause problems when they’re in the wrong place![1] As someone who works with clients struggling with digestive issues every day, I’ve seen firsthand how proper SIBO diagnosis and natural therapies can transform lives.

What Exactly Is SIBO?

SIBO occurs when bacteria that should primarily be in your large intestine find their way into your small intestine and multiply excessively.[1] Your small intestine should have relatively few bacteria compared to your large intestine, but when this balance is disrupted, symptoms emerge.

When you have SIBO, the excess bacteria in your small intestine start breaking down and consuming your food prematurely, before your body has a chance to digest and absorb the nutrients. This premature bacterial breakdown creates various gases (hydrogen, methane, or hydrogen sulfide) that lead to uncomfortable symptoms like bloating, pain, and other digestive troubles.

Common Symptoms of SIBO

Most people with SIBO experience:

• Bloating – especially after meals, sometimes severe enough to look “8 months pregnant” (as my clients often describe it!)
• Gas and excessive flatulence
• Abdominal pain and cramping
• Diarrhea, constipation, or alternating between both
• Excessive belching or burping
• Reflux, heartburn, or nausea (in some cases)

Interestingly, symptoms often worsen when you try to eat healthier foods like fruits and vegetables, or when taking probiotics. This counterintuitive reaction happens because bacteria feed on the fiber and fermentable carbohydrates in these foods.

Another telling sign: if you’ve ever taken antibiotics for something unrelated and noticed your digestive symptoms improved, SIBO could be the culprit.

What Causes SIBO?

Our bodies have multiple protective mechanisms to prevent bacterial overgrowth in the small intestine:

1. Strong stomach acid – kills bacteria we ingest
2. Migrating motor complex – wave-like contractions that sweep bacteria toward the large intestine
3. Pancreatic enzymes and bile – create an environment unfavorable for bacterial growth
4. Ileocecal valve – prevents backflow from the large intestine
5. Proper motility – keeps food and bacteria moving through the digestive tract

When these protective mechanisms fail, SIBO can develop. Several factors can increase your risk:

• Low stomach acid – which might be present if you consistently have low B12 or iron levels despite eating nutrient-rich foods
• Acid-suppressing medications – including proton pump inhibitors and certain antacids that reduce your natural digestive acid production
• Health conditions affecting gut movement – such as diabetes, autoimmune disorders like scleroderma, and imbalances in thyroid function
• Structural issues like adhesions, fistulas, diverticulosis, or strictures
• Previous abdominal surgeries
• Food poisoning – can trigger an autoimmune response affecting digestive motility
• Traumatic brain injury – disrupts vagal nerve communication
• Prolonged stress – impairs proper digestion and motility

How Is SIBO Diagnosed?

SIBO symptoms overlap with many other digestive conditions, making accurate diagnosis crucial. The most common diagnostic tool is a breath test, which measures hydrogen and methane gas levels after consuming a glucose or lactulose solution.[2]

Depending on the predominant gas produced, SIBO typically presents as:

• Hydrogen-dominant SIBO – usually causes diarrhea
• Methane-dominant SIBO – typically causes constipation
• Hydrogen sulfide SIBO – can present with various symptoms and often shows as a flat line on certain breath tests

Effective SIBO Therapies

SIBO treatment typically follows a multi-pronged approach:

1. Antimicrobial Treatment

Antibiotic Therapy:

• Rifaximin (Xifaxan) is the preferred antibiotic for SIBO. It works locally in the intestine and doesn’t cause all the damage typically associated with other antibiotics – a big plus![3]
• Treatment usually lasts about 10 days for hydrogen-dominant SIBO.
• For constipation-dominant (methane) SIBO, rifaximin may be combined with neomycin for better results.

Herbal Antimicrobials:

• Many of my clients choose this natural approach.
• A 2014 study showed herbal antimicrobials to be as effective as rifaximin for resolving SIBO.[4]
• Treatment typically lasts 4-6 weeks, longer than antibiotic therapy.
• Most people begin feeling better within 1-2 weeks of starting herbal protocols.

2. Improving Motility and Underlying Issues

Whether using antibiotics or herbal antimicrobials, addressing the root causes is essential for long-term success:

• Enhancing the migrating motor complex
• Improving overall digestive motility
• Addressing structural issues when possible
• Managing contributing conditions
• Identifying and healing from any post-infectious triggers

3. Dietary Approaches

A Low FODMAP diet is often recommended during the treatment phase. While it won’t eradicate SIBO on its own, it can provide symptom relief by reducing fermentable carbohydrates that feed bacteria. However, a low FODMAP diet should never be continued longer than 8 weeks due to the lack of fiber and nutrients, which negatively influences the microbiome.

Preventing SIBO Recurrence

SIBO has a high recurrence rate if underlying causes aren’t addressed. That’s why I focus on understanding what caused your SIBO in the first place. This approach significantly reduces the chances of SIBO returning after successful treatment.

When to Seek Help

If you experience persistent bloating, gas, abdominal pain, add nausea, burping, heartburn or irregular bowel movements, it’s worth consulting with a healthcare professional who understands SIBO. Early intervention can prevent nutritional deficiencies and more severe symptoms down the road.

Particularly significant red flags that might indicate SIBO include:

• Bloating that gets worse when you try to eat healthy foods
• Digestive symptoms that mysteriously improve when you take antibiotics for something else
• Your symptoms do not improve despite trying different dietary approaches
• Bloating every single time you eat
• Bloating that gets worse as the day progresses
• Unexplained burping, heartburn, or nausea

Final Thoughts

SIBO is a complex condition requiring a comprehensive approach.[5] While it can cause significant discomfort and frustration, proper diagnosis and therapy can provide relief and prevent recurrence. As a registered dietitian specializing in digestive health, I work with my clients to not only resolve current symptoms but also address the root causes of SIBO to restore long-term digestive wellness.

If you suspect you might have SIBO, I encourage you to reach out to a healthcare provider knowledgeable about this condition. With the right approach, you can overcome SIBO and finally regain digestive comfort!

Susan Gleaton is a Registered Dietitian trained in Integrative and Functional Medical Nutrition Therapy, specializing in complex digestive issues including SIBO. If you’re struggling with digestive symptoms that might be SIBO-related, schedule a consultation to discuss personalized testing and treatment options.

Footnotes

[1]: Ghoshal UC, Shukla R, Ghoshal U. Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy. Gut and Liver. 2017;11(2):196-208.
Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5347643/

[2]: Pimentel M, Saad RJ. Breath Testing for Small Intestinal Bacterial Overgrowth: Maximizing Test Accuracy. Clinical Gastroenterology and Hepatology. 2014;12(12):1964-1972.
Link: https://pubmed.ncbi.nlm.nih.gov/24095975/

[3]: Gatta L, Scarpignato C. Systematic review with meta-analysis: rifaximin is effective and safe for the treatment of small intestine bacterial overgrowth. Alimentary Pharmacology & Therapeutics. 2017;45(5):604-616.
Link: https://onlinelibrary.wiley.com/doi/full/10.1111/apt.13928

[4]: Chedid V, Dhalla S, Clarke JO, et al. Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Global Advances in Health and Medicine. 2014;3(3):16-24.
Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030608/

[5]: Rao SSC, Bhagatwala J. Small Intestinal Bacterial Overgrowth: Clinical Features and Therapeutic Management. Clinical and Translational Gastroenterology. 2019;10(10):e00078.
Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6884350/