However, a recent study of SIBO and IBS concluded "The data do not support an important role for SIBO according to commonly used clinical definitions, in IBS. However, mildly increased counts of small-bowel bacteria seem to be more common in IBS, and needs further investigation. Motility alterations could not reliably predict altered small-bowel bacterial flora."
Also the value of the latulose breath test for detecting SIBO is in question. Another recent study concluded "While interest in small bowel bacterial overgrowth in IBS continues, the utility and specificity of lactulose hydrogen breath testing is yet again called into question. Methane appears to slow intestinal transit and constipation appears more common among methane-positive patients."
In summary the role of SIBO in IBS is controversial and there is little substantive evidence yet to show it plays a significant role in IBS. However, a link has been shown between individuals with fructose malabsorption and possible SIBO. You can read about in this article
References Bratten, J. R. and M. P. Jones, 2007: Small intestinal motility. Current Opinion in Gastroenterology, 23, 127-133.
Posserud, I., P. O. Stotzer, E. S. Bjornsson, H. Abrahamsson, and M. Simren, 2007: Small intestinal bacterial overgrowth in patients with irritable bowel syndrome. Gut, 56, 802-808.
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