The purpose of this study is to determine whether a specifically designed multispecies probiotic decreases visceral hypersensitivity in IBS-patient (defined by an increased pain tolerance threshold). Moreover, the effect on general symptom scores and inflammatory and microbiological parameters will be studied.

Inclusion Criteria:

• Clinical diagnosis of IBS according to the Rome III criteria
• Increased visceral perception according to barostat measurements, defined as a pain tolerance threshold at smaller than or equal to 23 mmHg
• Age between 18 and 65 years
• BMI between 18.5 and 30 kg/m2

Exclusion Criteria:

• Known gastro-intestinal diseases
• Major abdominal surgery
• Previous radiotherapy, chemotherapy
• Clinical significant systemic diseases
• Critically ill patients or patients suffering from severe acute pancreatitis
• Patients with organs failure
• Patients receiving enteral feeding
• Excessive alcohol intake (greater than 15 consumptions per week)
• (planned) pregnancy or lactation
• Use of pre-, probiotics in the month before and during the study
• Use of antibiotics in the two months before and during the study
• Use of anti-diarrhoea medication, anti-laxatives or anti-acid medication in the two weeks before and during the study
• Use of anti depressives (especially SSRI's) in the month before and during the study
• Use of other medication if less then one month on stable dosage