Healthy digestive tracts are the home of billions of bacteria that should exist is the right numbers and types in the right sections of the intestine. Small Intestine Bacterial Overgrowth (SIBO) is a condition where normal gut bacteria overgrow in the small intestine. This can result in significant bloating, gas, abdominal pain, inflammatory symptoms and constipation, amongst other symptoms. SIBO can affect the absorption of nutrients and often causes deficiencies of iron, vitamin B12, and the fat soluble vitamins A, D, E and K.
In a gut where SIBO is a problem, an ounce of milk that would normally result in 50mL of gas if the milk sugars were not properly absorbed could create up to 5000mL of gas if the milk sugars are not properly absorbed. Yes, you read that right! It could make 100 times the volume of normal intestinal gas. (More about what other foods can be an issue in a moment.)
SIBO develops when the normal digestive functions are disturbed, leading to changes in how the body keeps the bacteria of the small intestine in check. This could include problems with:
Gastric acid secretion in the stomach. When gastric acid secretion is impaired, as in defcient hydrochloric acid production in the stomach, or in association with the chronic use of acid-blocking medications, swallowed bacteria are more likely to pass to the small intestine.
Motility (movement of food through the digestive tract). When motility is impaired, as in diabetic neuropathy, surgical scarring, or small bowel diverticulosis, food and bacteria can stagnate in the small intestine.
Immune function. When immunity is impaired—either by illness or dietary choices that irritate the gut— bacterial growth can go unchecked.
SIBO affects the elderly more than younger people, and it’s very common in patients with irritable bowel syndrome (but is it not equivalent to IBS, there can be more than one way to create symptoms that might be considered IBS). Studies show a prevalence of approximately 15% in elderly patients, more than 50% in patients with IBS, and more than 28% of patients with diabetes.
SIBO is associated with the use of proton-pump inhibitor drugs, pancreatic insufficiency, a history of bowel obstruction, celiac disease, liver disease such as cirrhosis, fibromyalgia, post-radiation of the abdomen, scleroderma, and Crohn's colitis.
Testing for SIBO
There are two laboratory options with SIBO.
The typical first test is the SIBO Breath Test. This test looks for the amount of methane and hydrogen resulting from fermentation of food by bacteria in the small intestine. These gases are absorbed into the bloodstream and carried to the lungs. Concentration of exhaled breath hydrogen and methane are measured in the test. Levels over the normal range are considered evidence of SIBO.
The second test is the Comprehensive Digestion and Stool Analysis. This test gives a great deal of information about the digestive process that may be setting you up for the SIBO state. Unfortunately, the culturing of bacteria from stool does NOT tell us about the state of bacterial growth in the small intestine!
Take a look at the Laboratory Testing Hub for more information about both of these tests.
SIBO is treated by two major approaches:
and the use of antibiotics (either conventional or natural).
Diet Therapy for SIBO
The diets that benefit SIBO are, inherently, low in carbohydrates. There are three main diets that can be useful in the mitigation of SIBO- the Specific (Special) Carbohydrate Diet, the GAPS diet, and the FOD-MAP diet.
The Specific Carbohydrate Diet (SCD) relies heavily on protein foods, including meats, poultry, eggs, and some beans. The SCD also allows lactose-free dairy, non-starchy vegetables, ripe fruits, nuts, seeds, and honey. The risk of the SCD is that patients may rely too heavily on fruits and honey, which can provide fermentation substrates for SIBO.
The Gut and Psychology Syndrome (GAPS) diet is a variant of the SCD that incorporates some of the guidelines of the Weston A. Price Foundation. The GAPS diet emphasizes protein-rich foods, vegetables, and lacto-fermented foods. Although there is some evidence that fermented foods might minimize some of the effects of SIBO, these probiotic-rich foods may also aggravate patients with SIBO.
Both the SCD and the GAPS diet can be combined with recommendations for the low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) diet. FODMAPs are carbohydrates that can serve as fermentable substrates for bacteria present in SIBO, and the low FODMAP diet has shown to benefit patients with IBS. The low FODMAP diet, however, is not specific to SIBO and does not eliminate polysaccharide-rich foods, such as grains and starchy vegetables. This diet must be modified to eliminate these starchy foods in cases of SIBO.
Dr. Gaul prefers that patients start with a phased-in version of the SCD diet. Look on the green sidebar of this page to find the main handouts that you will need to get started.
Good adherence to the dietary approach prescribed can minimize or eliminate symptoms in a short period - usually in 4 to 8 weeks. Depending on your individual response and the level of disorder in the small intestine, a version of this diet may be used for a longer period during therapy.
Supplemental Therapy for SIBO
Antibiotics are the standard conventional treatment for SIBO. But antibiotics do not address the underlying causes of the condition. To do that, you need a comprehensive, integrated approach that also includes diet and intestinal support.
Various natural antimicrobials, such as goldenseal, Oregon grape, artemisia, berberine, enteric-coated peppermint oil, cinnamon, and garlic can be effective against SIBO. These natural antimicrobial compounds can help keep bacteria in check. Dr. Gaul will work with you to select the right combination for you.