Small Intestinal Bacterial Overgrowth (SIBO)
Small Intestinal Bacterial Overgrowth (SIBO)
Small Intestinal Bacterial Overgrowth (SIBO) is a digestive condition where bacteria from the large intestine overgrow in the small intestine.
As these bacteria ferment food, they produce gases like hydrogen and methane, which can lead to bloating, pain, changes in bowel habits, slowed gut movement, and reduced nutrient absorption.
Common Symptoms of SIBO
Symptoms can differ from person to person, although the most common SIBO symptoms can include:
- Bloating
- Abdominal discomfort, Abdominal pain
- Nausea, Reflux, Burping
- Excessive wind
- Diarrhea, Constipation
- Early satiety, Unintentional weight loss
Is there a relationship between SIBO and IBS?
SIBO is reported more frequently in people with irritable bowel syndrome (IBS) than in those without digestive symptoms. Research estimates vary depending on the testing method and population studied, but some studies suggest that around one in three people with IBS may also test positive for SIBO. The true prevalence of SIBO in people without symptoms is still not well established.
Testing for SIBO
Breath testing is commonly used to detect elevated levels of hydrogen and/or methane gas. The gold standard is jejunal aspirate testing, this test extracts a small sample of fluid from the jejunum via an endoscope. This is often not performed given the invasive nature of this procedure.
How can a dietitian help me?
Conventional treatment for SIBO typically involves a course of antibiotics, such as rifaximin, which is used to reduce excess bacteria in the small intestine (1-3). Alongside medical treatment, working with a dietitian can help address nutritional deficiencies and provide structured dietary support.
A low FODMAP diet is sometimes trialled following antibiotic treatment to help manage symptoms and potentially reduce the risk of recurrence. This approach is based on the theory that reducing fermentable carbohydrates may limit fuel for bacterial overgrowth in the small intestine. However, current research is limited, and there is insufficient evidence to definitively support or refute this strategy (1).
Nutritional Support Addressing nutritional deficiencies is an important part of SIBO management, particularly for individuals experiencing weight loss or malnutrition. Targeted nutrition support can help improve nutrient status, reduce digestive symptoms, and support healthy weight restoration.
This may include the use of specific vitamin and mineral supplements, such as vitamin B12, iron, and calcium, as well as dietary adjustments. In some cases, a lactose-free diet may be recommended, as SIBO can impair lactose digestion. Some individuals may still tolerate fermented dairy products, such as yogurt.
Sources
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.
2. Aziz I, Tornblom H, Simren M. Small intestinal bacterial overgrowth as a cause for irritable bowel syndrome: guilty or not guilty? Current opinion in gastroenterology. 2017;33(3):196-202.
3. Gatta L, Scarpignato C, McCallum RW, Lombardo L, Pimentel M, D’Incà R, et al. Systematic review with meta‐analysis: rifaximin is effective and safe for the treatment of small intestine bacterial overgrowth. Alimentary Pharmacology & Therapeutics. 2017;45(5):604-16.
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