Small Intestinal Bacterial Overgrowth : Causes, Testing, Stages of Treatment Overview

Small Intestinal Bacterial Overgrowth (SIBO): What Is it?

Small intestinal bacterial overgrowth (SIBO) is a term used to describe the 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 per millilitre; normally, less than 103 organisms per millilitre are found in this segment.^[1] It is important to mention that we all have both good and bad bacteria colonizing the gut; SIBO could happen to anybody under favourable circumstances or conditions.

A proper balance of these two types of bacterial populations is imperative for “disease” prevention. SIBO is largely underdiagnosed, but it is now becoming more recognized and discussed by mainstream medicine. We all could become “infected” with SIBO at some point in our lives; there is also the chance of recurrence later in life when conditions are favourable 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 or 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 nonexistential for various 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.^[3] 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 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 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 or imaging methods will detect the presence of SIBO. If you have had a colonoscopy, ultrasound, and stool test with inconclusive answers for digestive symptoms, SIBO testing may be the next step. The three-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 or methane gas is measured. The lactulose solution serves as a substrate for the bacteria; hydrogen or methane gas 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.^[1] Approximately 80% of people who have been diagnosed with 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, irregular bowel frequency, and irregular consistency. Several therapeutic trials targeting gut microbes using antibiotics and probiotics have further demonstrated that not all symptoms in patients with IBS originate in the brain but rather in the gut, providing support for the microorganic basis of IBS.^[2] A study undertaken at Cedars-Sinai Medical Center used 448 subjects who were referred by their doctors for detection of SIBO. After completing a questionnaire, the researchers determined that 202 subjects could be considered as having irritable bowel syndrome according to standard symptom criteria. Of these, 157 (78%) were positive for bacteria overgrowth using the LHBT. The researchers conclude from this small study that subjects with IBS appear to have a high prevalence of SIBO.^[3] 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

Three sequential phases of SIBO treatment follow proper diagnosis: the preparation phase, the 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 two to six weeks. The preparation phase is often continued into the eradication phase.

The recovery phase is complex—it involves starving off SIBO remnants and 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: 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.^[4] The recovery phase generally persists for one or two 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

SIBO can manifest as IBS and fibromyalgia. Anyone with a positive history of gastroenteritis, food poisoning, or chronic GI upset should be assessed for SIBO. SIBO can result from low stomach acid, slow GI motility, or dysbiosis (as a result of underlying acute or chronic infections). SIBO is an underdiagnosed 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 stepwise 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 SIBO treatment is indicated for you—herb and drug interactions do exist.