What is SIBO? Part 1: Symptoms and Causes

Have you heard of SIBO?  I hadn’t heard of SIBO until I suspected that I had it.

SIBO stands for small intestine bacterial overgrowth. SIBO is a digestive disorder in which bacteria normally found in the large intestine migrates to the small intestine, where it becomes overgrown.  We need bacteria in order to live, but this is a case of the right bacteria in the wrong place. SIBO can wreak havoc on one’s health and is the main cause of a leaky gut.  To read more about leaky gut, click here. The actual number of healthy people with SIBO is not known, but it is estimated that approximately 80% of people with irritable bowel syndrome (IBS) have SIBO. 

Approximately 80% of people with irritable bowel syndrome (IBS) have SIBO. 

Normally, the small intestine has very little bacteria in comparison to the large intestine. Overgrown bacteria in the small intestine can cause a number of problems:

• Damage to Microvilli. The small intestine is like a shag carpet with microvilli “fingers,” which give the small intestine a huge surface area for absorption of nutrients. Bacteria produce methane and hydrogen gas, which damage the microvilli.  One function of the microvilli is to digest small starch molecules from food, and when the microvilli become damaged, the bacteria uses the small starch molecules to cause fermentation, creating more methane and hydrogen. This is uncomfortable and further damages the microvilli, creating a perpetual cycle and eventually leading to a leaky gut.  

• Malabsorption of Nutrients. When the microvilli become damaged by the bacterial overgrowth, nutrients cannot be absorbed into our body.  This may manifest in a wide variety of symptoms (see below).

• Slowed Motility. When the small intestine is not working properly due to the bacterial overgrowth, digestion (motility) slows down.  This results in even more fermentation as bacteria thrive in a digestive system which is sluggish. 

Nasty stuff!

How would you know if you have SIBO?  Symptoms can vary enormously from person to person. To complicate matters, a person can also be entirely asymptomatic. Here are some common associations with SIBO:

• Irritable bowel syndrome or inflammatory bowel disease

• Constipation or diarrhea or both

• Bloating after meals

• Gas, abdominal pain, or cramping

• Odorous, loose stools

• Food sensitivities or intolerances 

• Joint pain

• Fatigue

• Skin issues such as eczema, psoriasis, hives, rosacea or rashes

• Asthma

• Restless leg syndrome

• Unexplained weight loss

• Nutrient deficiencies 

• Autoimmune disease

The gold standard test for SIBO is a breath test.  When I suspected that I had SIBO, I asked for this test, but it was not available through conventional medicine.  I hope this will change in the future, but at the time I needed it, I turned to functional medicine.  I will discuss the SIBO breath test in next week’s blog. 

Treatment of SIBO is complicated.  Mild cases may respond to dietary changes, but severe cases require a combination of diet and either herbal or prescription antimicrobials.  Dietary approaches include:

• Specific Carbohydrate Diet

• Low FODMAP Diet

• SIBO Bi-Phasic Diet

• Elemental Diet

Learn more about the treatment of SIBO.

Meanwhile, you may be wondering what causes SIBO in the first place.  Common causes of SIBO include:

• Low stomach acid (read about stomach acid in this article)

• High sugar and starch diet

• Alcohol consumption

• Chronic stress

• Bacterial infections

• Medications (PPIs, H2 blockers, laxatives)

• Surgery scars or other structural issues

How are SIBO and rheumatoid arthritis connected?  Not everyone with rheumatoid arthritis has SIBO, and not everyone with SIBO has a leaky gut. However, if you have an autoimmune disease, you, by default, have a leaky gut.  SIBO is one of the causes of leaky gut, and leaky gut is the underlying condition in all autoimmune diseases. If SIBO isn’t treated, the gut cannot heal, and the immune system stays on high alert.

Do you think you may have SIBO?  If you do, it must be treated in order for the gut to heal so your immune system and your inflammation can calm down. If you want to learn more about SIBO testing, read this article. To learn about how to treat SIBO, read this article. If you’ve had SIBO in the past, learn about SIBO prevention here.

If you have any questions about SIBO, please send me a message or comment below. 

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