SIBO Explained: What to Know about Small Intestinal Bacterial Overgrowth

As research points to a connection between gut bacteria and health, getting tested for SIBO is worth considering for patients with undiagnosed gastrointestinal problems.

The small intestine connects the stomach to the large intestine, and it is the part of the digestive system where about 90% of food digestion and nutrient absorption takes place. A variety of enzymes, acids, bile and bacteria help to break down food particles into a form that can be absorbed into the tissues of the body.

When bacteria in the small intestine (also referred to as the small bowel) reaches excessive levels — a disorder known as Small Intestinal Bacterial Overgrowth, or SIBO — the result can produce unpleasant symptoms such as diarrhea or constipation, abdominal pain, abdominal distension, bloating and gas. SIBO can also lead to unintended weight loss, dehydration and fatigue because the condition can result in damage to the lining of the walls of the small intestine, making it more difficult to absorb essential nutrients during the digestion process.


Risk Factors for SIBO

One of SIBO’s distinct features is that it is much more likely to affect people who have already been diagnosed with another chronic condition, including:
  SIBO symptoms are quite similar to symptoms of many other conditions, so a patient with IBS, for example, might assume all of their symptoms are being caused by IBS, not realizing that some are actually from SIBO and should be properly diagnosed and treated. Other SIBO risk factors include older age; being female; a prior history of bowel surgery; and alcohol consumption. Long-term use of proton pump inhibitor medications (PPIs) is also a SIBO risk factor, since PPIs reduce acid production, thereby making it easier for bacteria to grow.
 

SIBO Diagnosis: Breath test

Diagnosing SIBO is typically done with a hydrogen breath test. It is a safe, simple and non-invasive diagnostic procedure that is relatively inexpensive and easy for the patient to tolerate. Bumrungrad is one of a small number of hospitals in Thailand that offer hydrogen breath testing, as it requires dedicated equipment and extensive technical training to be able to conduct the test properly and measure the results accurately.
 
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The purpose of the test is to identify whether any hydrogen or methane is present in the patient’s breath, a positive indication for a SIBO diagnosis. That is determined by having the patient exhale into a balloon or container several times at specific time intervals, usually every 20 minutes, and after the patient has consumed a liquid at the start of the test. The full test is spread over two to three hours — for most of that time, the patient can relax at their leisure until it is time to provide the next breath sample.
 
Patients are required to follow certain pre-test restrictions, including fasting for the 12-hour period leading up to the test. A full set of instructions is provided in advance of the test.
 

SIBO Treatments

A number of antibiotics have been shown to be effective in reducing the bacterial overgrowth caused by SIBO. For patients who have another underlying condition, receiving proper treatment for that condition may also help reduce bacteria production in the small intestine. In addition to antibiotics, doctors may recommend dietary changes and nutritional supplementation for patients with nutritional deficiencies related to SIBO.

Until now, the medical community has still not developed a full and complete understanding of what causes SIBO, and what kind of impact it might have when a patient has another chronic condition. That is beginning to change with more attention being paid to the gut microbiome in health and disease. Patients who are currently experiencing SIBO-type symptoms are advised to talk to your doctor about whether you should be tested for the condition.  
 
 
By Dr. Vibhakorn Permpoon, a specialist in Gastroenterology and Hepatology at the Digestive Disease Center, Bumrungrad International Hospital
 

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