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November 10, 2004

Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome

Author Affiliations

Letters Section Editor: Robert M. Golub, MD, Senior Editor.

JAMA. 2004;292(18):2213-2214. doi:10.1001/jama.292.18.2213-a

To the Editor: On reading Dr Lin’s discussion of the hypothesis of small intestinal bacterial overgrowth (SIBO) as a framework for understanding irritable bowel syndrome (IBS),1 I have concerns that the only data put forward are at best indirect, and that alternate conclusions could be drawn from the given findings.

Our report of whole-body calorimeter measurement of 24-hour excretion of hydrogen and methane2 (reference 19 in the article) is referred to incorrectly. Higher hydrogen volumes and 4-fold greater maximal rates of excretion were observed in patients compared with controls, all of whom were eating the same “standard Western diet,” not following lactulose ingestion as was stated. Patients and controls were provided identical food for 14 days prior to measurement, with 3-day rotation of fixed diet. The second reported study from the same group3 (reference 21 in the article) used the same methodology, which is also misstated. Whole-body excretion of hydrogen and methane after lactulose has, to my knowledge, not been studied in IBS patients but would require a prolonged period of measurement, perhaps 18 hours.4