Small intestine bowel overgrowth (SIBO) might not be a familiar term, but it plays a key role in irritable bowel syndrome (IBS). It is also involved in successfully treating rosacea, fibromyalgia and other conditions.
What is SIBO?
The large intestine or colon is home to a large number of bacteria. In comparison, the small intestine has 10,000 to 100,000 times fewer bacteria. However, if there are more than 10^5 bacteria per milliliter (ml) in the small bowel, this is considered small intestine bowel overgrowth (SIBO). Typical symptoms of SIBO include nausea, gas, bloating, constipation, abdominal discomfort, diarrhea, fatigue, and even malabsorption and weight loss.
These symptoms are incredibly similar to those of irritable bowel syndrome (IBS), and some studies have shown that up to 80% of patients with IBS have SIBO. A 75% improvement in IBS symptoms has been observed following therapy for SIBO, making a strong argument for treating underlying SIBO to reverse symptoms such as postprandial bloating and distension, altered motility, and increased gut sensitivity.
With SIBO, there is increased permeability of the small intestinal wall, similar to leaky gut syndrome. This allows large, unwanted food proteins to enter the bloodstream, causing a hypersensitive immune response which contributes to chronic disease.
Risk factors for SIBO
Factors that increase the likelihood of having SIBO include:
* Altered intestinal bacteria from antibiotic use, gastroenteritis, or inherited immune system disorders
* Chronic use of proton-pump inhibitors (e.g., Nexium, Prolosec)
* Anatomical changes in the small bowel from surgery, Crohn’s disease, or IBS
* Conditions that impact bowel motility, such as diabetes, scleroderma, and celiac disease
* Not producing enough digestive enzymes, or chronic pancreatitis
Ileocecal valve dysfunction is also associated with an increased likelihood of developing SIBO. A poorly functioning ileocecal valve has been shown to be highly correlated with symptoms in SIBO, such as loss of appetite, bloating, and feeling excessively full after meals.
How SIBO affects other conditions
Fibromyalgia
The causes of fibromyalgia remain poorly understood, but lactulose breath testing, used to test for SIBO, is abnormally elevated in people with fibromyalgia. Researchers also demonstrated a correlation between the amount of fibromyalgia pain and the degree of breath test result abnormalities. A later study showed increased fibromyalgia pain correlated with increased intestinal permeability, or leaky gut.
Rosacea
SIBO is also thought to play a significant role in the skin rash condition rosacea. Significantly more people with rosacea had an abnormal hydrogen breath test (47%) compared to people without rosacea (5%), indicating abnormal intestinal bacteria as a likely cause or strong contributor. Interestingly, patients with abnormal breath tests who were treated with the antibiotic rifaximin achieved complete remission of rosacea for longer than nine months. Additionally, those few who did not recover from rosacea were also found to still have bacterial overgrowth and were treated again with rifaximin, which cleared up their rosacea rash.
Improvement in rosacea symptoms can also be achieved by avoiding bread and simple carbohydrates, which is believed to lower fermentation of bacteria.
SIBO treatment
Treatment for SIBO is similar to that for IBS. It often involves a combination of dietary changes, such as avoiding certain trigger foods, and prescription antibiotics that predominantly stay in the digestive tract and have no clinically relevant bacterial resistance. The most effective antibiotics for this purpose are rifaximin and metronidazole.
