SIBO: What Is the Underlying Cause?

Small intestinal bacterial overgrowth (SIBO) is associated with IBS and can be a primary cause of gastrointestinal symptoms. To eradicate SIBO, the underlying cause needs to be understood and treated.¹

What is SIBO?

SIBO occurs when bacteria that usually reside in the large intestine end up in the small intestine. This is due to a slowdown in the transit time of food through the gut, which decreases the normal clearance of bacteria. Often seen in people with SIBO is dysbiosis, or an imbalanced microbiome. Common symptoms include bloating, abdominal pain, constipation/diarrhea, and/or anemia.^1,2

If you’re wondering if you have SIBO, find a health practitioner or doctor who can arrange testing for you.

Underlying causes of SIBO

Here are the main underlying causes that need to be addressed to resolve SIBO.

1. Altered motility

Motility is an important concept to understand in SIBO. Motility, or the migrating motor complex
(MMC), is a pattern of activity that happens in the gastrointestinal tract during fasting. For most people, this is usually overnight. The MMC sweeps the intestines, moving chyme, secretions, and bacteria along. This movement usually prevents SIBO from occurring.^1,2

Due to a range of issues, motility can slow down, which may lead to SIBO. These issues include:^1,2

• Adhesions from endometriosis or from abdominal surgery
• Changes in motility from infections like traveler’s diarrhea or food poisoning
• Neuropathy or nerve damage (such as damage to the vagus nerve)
• Pelvic floor dysfunction
• Medications such as opioids, proton pump inhibitors, or anticholinergics
• Aging – Older adults are at higher risk for SIBO because they may produce less gastric acid that helps break down food. They are more likely to have health conditions or complications that can affect their digestive system.

2. Changes or damage to the mechanics or structure of the gut

These can include:^1,2

• Ileocecal valve dysfunction
• Tumors, polyps, diverticulosis, or endometriosis
• Changes to anatomy due to surgery such as gastric bypass
• Small intestine stricture or fistula

3. Systemic health issues

SIBO can be associated with systemic health issues such as:^1,2

• Diabetes
• Parkinson’s disease
• Systemic sclerosis
• Celiac disease
• Crohn’s disease
• Chronic kidney failure
• Hypothyroidism
• Cystic fibrosis
• Multiple sclerosis
• Alcoholism
• Fibromyalgia
• Lupus

4. Other conditions of the gut

These may include:^1,2

• Antibiotic use, which disrupts the microbiome
• Impaired gastric acid and bile production – These protect the body from bacteria passing through the intestines after eating.
• Lactase/small intestine enzyme deficiency
• Pancreatic insufficiency
• Gastroparesis
• Liver disease/cirrhosis
• Autoimmune gastritis
• Helicobacter pylori infection

5. Impaired immune system

Immune system disorders may include:^1,2

• Immunoglobulin A (IgA) deficiency, which impacts the immune system’s ability to fight off infections
• Common variable immunodeficiency (CVID), an immune disorder that presents with
  frequent infections and low antibody levels
• Immune conditions such as HIV
• Chronic stress or trauma, which weakens the immune system

If you suspect you have any underlying conditions, talk with your health practitioner so they can
work out a plan to achieve the best success with your SIBO treatment.