sponsor decided they are not interested in the study due to finacial reasons

Probiotics are defined as 'mono- or mixed cultures of live micro-organisms which, when applied to animal or man, beneficially affect the host by improving the properties of the indigenous flora'. Certain probiotics possess potent antibacterial and antiviral properties. Probiotic antibacterial activity may derive from the direct secretion of bacteriocins, the elaboration of proteases directed against bacterial toxins or through their ability to adhere to epithelial cells and thus exclude pathogens. The antiviral properties of some probiotic organisms, including the stimulation of interferon production, together with the well-documented efficacy of certain probiotics in the therapy of rotavirus diarrhea suggests the potential for a role for these agents in PI-IBS. The efficacy of some probiotics in preferentially relieving 'gas-related' symptoms may be related to qualitative changes in the colonic flora, as described earlier, or through the suppression of Small intestinal bacterial overgrowth (SIBO) , as there are reports of efficacy of probiotics in SIBO.

The aim of the proposed study is to investigate whether the probiotic preparation "co biotic" can change the composition of fecal bile acids, fatty acids and bacterial composition, and whether such changes, if they occur, are correlated to a change in the symptoms of patients with IBS.

Materials and methods:

Patients diagnosed as having IBS by the Rome III criteria will be included in the study.

Study subjects will be interviewed by a physician who will asses the diagnosis of IBS according to the Rome III criteria. Subjects will sign an informed consent and fill an IBS questionnaire and a health related quality of life questionnaire,

A fecal sample will be obtained

The subject will receive the probiotic product in a dose of 2 tablets/day, or a placebo containing all the active ingredients in the probiotic capsule, besides the bacteria, for 4 weeks. They will then enter a washout period of 2 weeks in which they will not receive anything, and then another 4 weeks in which they will receive the probiotic product in a dose of 2 tablets/day, or a placebo. Patients will be randomized so that they will receive the study drug for 4 weeks and the placebo for 4 weeks, in a double-blinded fashion. Thus each patient will be his own control.

Inclusion Criteria:

• IBS by Rome III criteria

Exclusion Criteria:

• other GI disease