By S. Anderson, M.D.
The medical community long thought that irritable bowel syndrome
(IBS) had no structural abnormality but would look at stress and
other psychological causes. This is quickly being debunked by new
research. When one suffers from IBS with CFIDS/ME, a recent study
has found a there is a post-infectious IBS (PI-IBS) produced by
low-levels of inflammation. This has been shown by lymphocytic
infiltration in the mucosa of the gut along with more permeability
and an increase in other inflammatory components that include
enterochromaffin and mast cells.
Steroid treatment has not proven to be effective although some
preliminary studies of probiotics may prove beneficial (McCarthy
et al). The studies are concentrating on balancing the
interleukin-10 and interleukin-12 but are not yet complete. Studies
that delve into serotonin as well as histamine metabolism may also
The idea of IBS developing after an infection was first
described in 1962 but the actual study of the mechanisms is quite
new. The severity of the disease along with gender seem to put one
more at risk for IBS. Since 2003, the research in this area has
exploded! The largest study to date was one that found 63% had
diarrhea as a predominating factor while 24% alternated between
diarrhea and constipation and 13% had mostly constipation. Bloating
was part of all groups suffering with PI-IBS.
Interestingly, only a small percentage of those with PI-IBS had
a history of psychiatric features such as anxiety or depression (Curr
Opin Gastroenterol, 2006, 22/1). The above mentioned
enterochromaffin cells contain serotonin and Dunlop et al
have demonstrated that this is also found in plasma levels.
Interestingly, those with constipated IBS had depressed serotonin
release. Two studies (Gwee et al, Wang et al) found an
increased type of interleukin in PI-IBS but not IBS that did not
have an infectious origin. These researchers also linked mast cells
to PI-IBS and found the mucosal nerves were affected by the mast
cells correlating closely with severity and the frequency of
The recent studies of PI-IBS over the last two years that
demonstrate increased inflammatory mediators that include serotonin
and cytokines could prove helpful to many that suffer from this
along with their CFIDS/ME as the work advances.