There is an association between other GI infections and the onset of IBS.Most of that work was done in the UK (they have better databases for data mining than we have in the US and what they looked at was diagnosed GI infection diagnosed IBS and matched GI infected vs non-GI infected and found that infection increased the frequency of IBS something on the order of 10X during the year following a GI infection) where Giardia, I believe, isn't much of an issue.However, I have no reason to suspect that Giardia would behave differently than other GI infections as the problem appears to be the damage from the inflamation which is a genral thing seen in most infections rather than something that is specific to a particular species.K.------------------I have no financial, academic, or any other stake in any commercial product mentioned by me.My story and what worked for me in greatly easing my IBS: http://www.ibsgroup.org/ubb/Forum17/HTML/000015.html