February 12th, 2019

Small Intestinal Bacterial Overgrowth (IBS)

Small intestinal bacterial overgrowth (SIBO) is a term used to describe the end result of movement of bacteria from the large intestine into the small intestine. SIBO is defined as a bacterial population in the small intestine exceeding 105-106 organisms/mL; normally, less than 103 organisms/mL are found in this segment.  SIBO is largely underdiagnosed, but is now becoming more recognized and discussed by mainstream medicine. We all have the ability to become “infected” with SIBO at some point in our lives; there is also the chance of recurrence later on in life when conditions are favorable for these bacteria.

Causes:

The two main predisposing factors to SIBO development include impaired gastric acid secretion (also known as low stomach acid), and small intestine dysmotility. There are many other predisposing factors such as the presence of diverticula, strictures, and recurrent antibiotic or medication use.  Acute or chronic infections can also create the ideal terrain for these bacteria to flourish.

Stomach acid secretion may be diminished or non-existential for a number of reasons: an aging population generally secretes less hydrochloric acid; chronic stress slows down our digestive function; medication use (such as proton-pump-inhibitors) also reduces stomach acid production and this predisposes us to infection.  Adequate stomach acid is important to defend the body against pathogen ingestion and colonization.  Other medications (opioids, prokinetics, anticholinergics) are known to slow GI motility and this can lead to the development of SIBO as well. On the other hand, small intestine dysmotility occurs as a result of disrupted communication between the brain and small intestinal smooth muscles.  This disrupted communication occurs as a result of toxins being released from bacterial infections, where the normal peristaltic motion of the intestinal smooth muscles is disrupted.  Therefore, people with a history of gastroenteritis and/or food poisoning, and who have never been well since then should be tested for SIBO.   Those who get sick or catch a bug while traveling overseas are also good candidates for SIBO testing. Slow GI motility allows bacteria from the large intestine to migrate up into the small intestine, and whatever residual small intestinal bacteria to remain, where they can thrive off of glucose and other energy sources in order to flourish.  As a side note, it is important to mention that food is absorbed within the small intestine; bacteria in the large intestine are quite happy to colonize this segment of the GI tract.

Testing:

Few testing and/or imaging methods will detect the presence of SIBO.  If you're someone who has had a colonoscopy, ultrasound, and stool test with inconclusive answers for digestive symptoms - SIBO testing may be the next step.  The 3-hour lactulose breath test is a common testing method used by Naturopathic Doctors.   Breath samples are collected in test tubes at 20 minute intervals, and the amount of hydrogen and/or methane gas is measured.  The lactulose solution serves as a substrate for the bacteria; hydrogen and/or methane gases are emitted as a by-product.   Hydrogen-producing bacteria are generally responsible for symptoms of diarrhea/loose stools, whereas the presence of methane-producing bacteria generally presents clinically as harder stools/constipation. For most people, it takes 120 minutes for material to pass from the upper GI tract into the large intestine – the first 120 minutes of testing gives crucial information regarding possible overgrowth.

Symptom Presentation:

People with SIBO vary widely in presentation, from being mildly symptomatic to suffering from chronic diarrhea, weight loss, and malabsorption.  Approximately 80% of people who have been diagnosed with the irritable bowel syndrome are infected with SIBO.  Irritable bowel syndrome is classified as a diagnosis of exclusion in those individuals who present with symptoms of abdominal pain relieved by defecation, and irregular bowel frequency and consistency. Those people presenting with widespread pain, as in fibromyalgia, should also be tested for SIBO.  Symptoms of SIBO include but are not limited to: bloating/distension, gas, cramping, nausea, aches and pains, and abdominal discomfort.

Treatment:

There are three sequential phases of SIBO treatment following proper diagnosis: the preparation phase, eradication phase, and the recovery phase.  Each phase serves its own unique and important purpose.   
The preparation phase is important to ensure that the liver’s ability to eliminate toxins, detoxify, and rid the body of bacterial end-product is maximized.  If liver function is sluggish and toxins are not eliminated properly, the individual may feel worse as toxins pool into the system during the eradication phase and become reabsorbed.  This phase is also necessary to ensure the bacteria are effectively targeted during the eradication phase: breaking up bacterial biofilms is an important step in the treatment process. The preparation phase usually lasts for a minimum of two weeks before the eradication phase begins.

The eradication phase involves the use of natural antimicrobials to target the bacteria.  Certain antibiotics may also be used for eradication during this phase.  Natural antimicrobials are rotated on a biweekly basis to ensure bacterial resistance does not occur.  This phase can persist anywhere from 2 to 6 weeks.  The preparation phase is often continued into the eradication phase.

The recovery phase is complex - it involves starving off SIBO remnants; restoring balance/homeostasis within the body: restoring gastric acid levels, stimulating the MMC, and optimizing gut health via repair and colonization with good bacteria.  Diet is very important during this phase only – an anti-SIBO diet starves off any remnants.  The anti-SIBO diet consists of low FODMAPs (foods in which the bacteria do not feed off of: white rice, eggs, white sugar, cashews, oils, meat, and low fermentable veggies and fruits to name a few).  A study shows that 75.6% of the ninety patients who were followed for a period of 15 months, and who were adherent to the diet, noticed symptom improvement. The recovery phase generally persists for 1-2 months.  Restoring balance with probiotics should be done with caution, and prebiotic-containing probiotics are to be avoided. Prebiotics act as an energy/fuel source for SIBO and this can prevent complete elimination.
 
Conclusion:
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SIBO can manifest as IBS and fibromyalgia.  Anyone with a positive history of gastroenteritis, food poisoning, and who has chronic GI upset should be assessed for SIBO.  SIBO can result from low stomach acid, slow GI motility, and dysbiosis (as a result of underlying acute or chronic infections).  SIBO is an under-diagnosed condition but it is becoming more accepted as a cause for symptoms.  The breath test is the most widely used testing method to detect hydrogen or methane gases emitted by these bacteria.  Hydrogen-producing bacteria are responsible for diarrhea-like symptoms whereas methane-producing bacteria are responsible for constipation-predominant symptoms.  It is possible for breath testing to reveal infection with both types of bacteria as well. SIBO treatment is done in a step-wise approach; it is lengthy and requires patience but for those who follow protocol and who see it through often achieve great results.  Speak with your Naturopathic Doctor about testing, and to determine whether or not SIBO treatment is indicated for you - herb and drug interactions do exist.