A randomised, placebo controlled double blind study to assess the efficacy of a probiotic dairy product containing Lactobacillus casei Shirota on symptoms, visceroperception and inflammation in Irritable Bowel Syndrome.

Patients will be included when:

1. Diagnosed with IBS according to the ROME II criteria.

2. Age between 18 and 65 years.

3. Giving informed consent

4. Minimum mean symptom score > 2 (scale 0-20 for the 5 symptoms: discomfort, pain, constipation, diarrhea and bloating) during pre run-in.

1. Patients who have had gastrointestinal surgery resulting in gastric resection, small intestinal or colonic resection.

2. Patients who are allergic to milk protein

3. Patients who have a high intake of yogurt (over 500 ml per day)

4. Patients where LcS was detected before the start of sample ingestion in the fecal samples.

5. Patients not able to stop medication that influences stool frequency (laxatives or antidiarrhoeals)

6. Patients who are vegetarians.

7. Patients who have used probiotics in a period of four weeks prior to the start of the study.

8. Patients who have received antibiotics/antibacterials in a period of four weeks before the start of the study and during the intervention.

9. Patients who did not commit to drinking the minimum dosage of the samples

10. Patients whose submission of fecal samples was done after stopping drinking samples and

11. Patients who submitted fecal samples more than two days earlier than the end of the drinking period

12. Patients with any relevant neurological, cardiovascular, pulmonary, metabolic, haematological or endocrinic disorder that is not stabilised.

13. Patients who have participated in a clinical study with an unregistered (clinical trial) product within four weeks before the start of the study.

14. Patients with a history of drug or alcohol abuse.

15. Any medical condition which the investigator considers sufficiently serious to interfere with the conduct of the trial or that constitutes any risk to the patients.