Posted on: January 21, 2016 at 9:40 pm
Last updated: September 30, 2016 at 1:12 pm

An estimated 6-15% of healthy people have SIBO, and up to 80% of people with irritable bowel syndrome (IBS) have SIBO. I often suspect SIBO in my patients when they say they feel bloated, uncomfortable, and have bowel irregularities “no matter what I do or eat”.

What is SIBO?

SIBO is an overgrowth of bacteria in the small intestine. In a normally functioning gut, there is a small number of bacteria that colonize the small intestine, and a much, MUCH larger number of bacteria that colonize the large intestine. As food travels down the digestive path it reaches the small intestine first, where further breakdown of the food and absorption of nutrients occurs. Next, the food reaches the large intestine (where it encounters more bacteria) and there, the gut re-absorbs water and bulks up the soon-to-be stool.

In people with SIBO, there is an overgrowth of bacteria in the small intestine with bacteria that should normally be found in the large intestine. This excess bacteria feasts on food particles in the small intestine before it has the chance to be fully broken down and absorbed. This feast causes bloating, pain, constipation, diarrhea, and gas.


The bacterial overgrowth also causes inflammation that damages the lining of the small intestine. As a result, we get reduced absorption of certain nutrients like vitamin A, B12, and D, and an increased amount of food intolerances and inflammation in the body.

What causes SIBO?

A variety of factors can alter the amount of bacteria living in the small intestine. Low stomach acid, taking antacid medications, antibiotics, being on the birth control pill, and drinking alcohol are common causes of SIBO.

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How is SIBO diagnosed?

Breath testing is the primary test used to diagnose SIBO. It measures hydrogen and methane produced by bacteria in the small intestine that is exhaled from the lungs.

To do the test, patients drink a solution of lactulose, which is a sugar that only bacteria can break down. After bacteria consume lactulose they produce a gas, which is reflected in levels of hydrogen and methane measured on the breath test. A glucose breath test can also be used to diagnose an overgrowth in the first two to three feet of the small intestine, where humans normally absorb glucose.


How is SIBO treated?

To treat SIBO the overgrowth of bacteria in the small intestine must be killed. MDs use pharmaceutical antibiotics, while NDs use natural herbal antibiotics. Protocols can vary, but usually include allicin (from garlic), berberine, oregano, olive leaf extract and other potent antimicrobial herbs. It is also important to disrupt bacteria’s defense system (called a biofilm) by using supplements like NAC and certain enzymes.

Dietary changes must also be made to help starve the bacteria and reduce symptoms during the “killing” phase of treatment. I recommend the low FODMAP diet, which has a low amount of fermentable foods. The Specific Carbohydrate Diet is similar to the low FODMAP diet and also shows success with SIBO.

After treatment, the breath test(s) can be repeated to confirm eradication. The bowels should then be re-colonized with good bacteria using a quality probiotic, and the lining should be healed with a protein called L-glutamine.


SIBO can recur in up to 50% of patients, so it’s important to monitor the diet and eliminate the factors that may have initially caused the SIBO.

This article was republished with permission from

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Dr. Shawna Darou
Naturopathic Doctor
Contributor to The Hearty Soul.

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