Does bacterial overgrowth in the small intestine play a role in irritable bowel syndrome in children?

When kids often complain about stomach pain, in most cases, no clear cause is found. These children are typically diagnosed with "functional abdominal pain," which includes irritable bowel syndrome, according to the Rom-III criteria.

Factors like altered movement of the intestine, heightened sensitivity, changes in gut bacteria, and social-psychological issues play a part in this disorder's origin.

Moreover, some early studies suggested that high bacteria levels in the small intestine (SIBO) might be linked to functional pain.

Researchers from the Netherlands studied children aged 6-18 with this diagnosis. They tested the breath of 161 children after giving them glucose. They checked for hydrogen exhalation every 15 minutes. If the child exhaled more than 20 ppm of hydrogen when fasting or if the hydrogen level rose more than 12 ppm, it indicated bacterial overgrowth.

18 kids (11.2%) exhaled more than 20 ppm when fasting, averaging 26.2 ± 5.7 ppm. Six kids (3.7%) showed a rise in exhalation over 12 ppm, averaging 16.5 ± 7.8 ppm. One child showed both symptoms. Usually, the rise appeared within 30 minutes.

The topic of functional stomach pain and SIBO is debated. Some argue that if bacterial overgrowth is diagnosed, there's a physical reason for the pain, contradicting the definition of "functional" pain. However, the line between physical and functional causes is blurry.

But the study has some validity: the SIBO rate is lower than in past studies. Also, patients with altered bowel patterns, belching, and appetite issues more frequently had bacterial overgrowth, which fits with our understanding of the issue.

Most children were diagnosed with SIBO due to increased fasting exhalation. This measure can be distorted if non-absorbable carbs are eaten the night before the test, but the study tried to control for this.

However, questions remain. We should check if the increased fasting exhalation happens consistently over multiple days. Furthermore, to prove SIBO's significance to symptoms, antibiotics should be tested in a blind study to see if they relieve symptoms.

Overall, when conducting breath tests with lactose and fructose, we should closely watch for high fasting exhalation and early rises and frequently add glucose breath tests.

Based on experience, bacterial overgrowth in the small intestine is often overlooked in pediatric gastroenterology.