IBS Diagnosis? What you should know about SIBO.
You walk out with a diagnosis of IBS after all the tests come back “normal” but you feel anything but normal. Your day and thoughts are ruled by GI issues, and where the bathroom is - this is not living! So, let’s talk about ONE thing that could be driving your IBS - SIBO or Small Intestinal Bacterial Overgrowth.
How SIBO and IBS are connected:
SIBO is a form of gut dysbiosis that can affect up to ~ 80% of those diagnosed with IBS. SIBO is classified as a functional gastrointestinal disorder characterized by an abnormal amount of bacteria in the small intestine where under normal conditions, the large intestine is where the majority of our gut bacteria live. SIBO can be classified by 3 types depending on the gas produced by the bacteria:
Hydrogen Dominant
Methane Dominant (also known as intestinal methane overgrowth (IMO))
Hydrogen Sulfide Dominant
Signs and Symptoms
SIBO can manifest with various gastrointestinal symptoms such as:
Bloating (after fiber, starches, and sugar)
Abdominal Pain or Discomfort
Diarrhea/Constipation or Mixed
Flatulence
Reflux
Weight Loss - more often associated with hydrogen dominant
Weight Gain - more associated with methane dominant.
Common Nutrient deficiencies: Fat soluble vitamins (D, A, E, K), B12, calcium, magnesium, and iron
Additionally, seemingly unrelated symptoms may be manifestations of SIBO outside of the GI tract.
Brain fog
Memory issues
Anxiety
Depression
Skin issues like rosacea
With 70% of the immune system residing in the gut, damage to the gut from SIBO has far reaching effects. In an imbalanced gut, lipopolysaccharides (LPS) are toxic inflammatory byproducts produced in the gut that eventually wind up in circulation causing an inflammatory cascade throughout the body. SIBO predisposes us to increased LPS and LPS predisposes us to SIBO. As a result of a chronic inflammatory state, we may be more at risk of other disease processes such as memory impairment, insulin resistance, increased cardiovascular risk, and autoimmune conditions to name a few.
Diagnosis
Diagnosing SIBO involves a thorough assessment of medical history, symptoms, and diagnostic tests. Common diagnostic methods include:
Non-invasive Breath Tests:
These tests measure the levels of hydrogen and methane in the breath after ingesting a specific carbohydrate solution of either glucose or lactulose. The test is a 3 hour long test and can be performed either in your GI’s office or at home. Diagnosis varies based on the amount and type of gas the bacteria produce from the testing solution and the time at which it shows up in the testing. The SIBO testing we use here is through Genova Diagnostics.
Invasive testing: a jejunal aspirate is a more invasive test where a sample of fluid is removed from the top of the small intestine and sent to the lab for testing.
What Causes SIBO?
There are many root causes of SIBO and within the causes some of them may even overlap. Below are some of the causes but it’s important to determine your root cause.
Impaired Motility:
Traumatic brain Injury
Vagus nerve dysfunction
Ehlers-Danlos syndrome
Hypothyroid
Opioid and/or anticholinergic use
Structural Abnormalities and adhesions:
Surgery such as c-sections, bariatric surgery, gallbladder removal other abdominal surgeries
Anatomical abnormalities
Endometriosis
Short bowel syndrome
Hypochlorhydria: Low stomach acid levels can fail to adequately sterilize ingested food, allowing bacteria to survive and thrive in the small intestine. Refer to the last blog post on stomach acid to learn about reasons why it may be low.
Pancreatic insufficiency
Food Poisoning
Conditions that affect the vagus nerve: like traumatic brain injuries, falls, stress or trauma
Ileocecal Valve Dysfunction
Infections: Mold/mycotoxins, environmental toxins, parasites, viral
Digestive Disorders: Certain gastrointestinal conditions like Crohn's disease, or celiac disease, can increase the risk of developing SIBO.
Treatment and Management
SIBO often requires a multi-faceted approach to address the overgrowth, alleviate symptoms, provide digestive and motility support, while working to address the root cause.
Some common treatments to reduce the number of bacteria in the small intestine include:
Antibiotics:
Standard treatments include Rifaximin for hydrogen dominant, combined with neomycin for methane dominant
2 week courses
May need multiple courses
Not everyone responds to these
Expensive
Antimicrobials/herbals: different combinations of herbals depend on the type of SIBO/IMO. Courses often last at least 4 weeks.
Elemental Diet: A medical food/beverage that is solely consumed over 14-21 days
In addition to eradication of the bacteria in the small bowel the following are other management components of a comprehensive approach.
Dietary changes like a LowFODMAP diet can help manage symptoms but alone are not a treatment for SIBO and a restrictive diet is not meant to be long term. The pros of a dietary change are symptom reduction but the cons are fear of food, removing foods that may not need to be removed, and decreasing microbial diversity when used longer than recommended
Probiotics: when it comes to SIBO not all probiotics are equal. Certain strains are beneficial with SIBO and others should be avoided.
Providing digestive support is another key element as the digestive secretions are often inadequate as a result of SIBO or are an underlying driver of SIBO.
Motility support is another key piece of a comprehensive SIBO plan to help prevent relapse.
Rebalancing and repairing the gut beyond treatment is another critical component of a comprehensive approach with SIBO
SIBO can be often overlooked as a cause of IBS and while it may be a cause of IBS it can be a symptom of something greater. Talking with a provider well versed in SIBO will help uncover what could be driving your IBS and SIBO could be the first step in uncovering the pieces of the puzzle. Think you may have SIBO based on what you read here? Reach out, I can help!
References:
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Efremova I, Maslennikov R, Poluektova E, Vasilieva E, Zharikov Y, Suslov A, Letyagina
Y, Kozlov E, Levshina A, Ivashkin V. Epidemiology of small intestinal bacterial
overgrowth. World J Gastroenterol. 2023 Jun 14;29(22):3400-3421. doi:
10.3748/wjg.v29.i22.3400. PMID: 37389240; PMCID: PMC10303511.
Ghoshal UC, Shukla R, Ghoshal U. Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy. Gut Liver. 2017 Mar 15;11(2):196-208. doi: 10.5009/gnl16126. PMID: 28274108; PMCID: PMC5347643.
