This study evaluates the effect of a symbiotic fermented milk on health-related quality of life and irritable bowel syndrome (IBS) symptoms in patients with constipation-predominant IBS.

Irritable bowel syndrome (IBS) is one of the most common digestive disorders in the developed world which. It is associated to numerous symptoms, of which the most characteristic are recurrent pain or discomfort in the abdominal region, changes and difficulties related to bowel movements, and bloating. Although not dangerous, the disease may significantly impair the patients' quality of life. Treatment is symptomatic, but currently not very efficient. The use of probiotics in the treatment of IBS is a promising approach and has been the subject of much research in the last two decades.

The purpose of this randomized, placebo-controlled study is to assess changes in health-related quality of life in patients with constipation-predominant IBS after regular consumption of symbiotic fermented milk (containing probiotics and dietary fibres) and to assess its effects on some symptoms, like abdominal pain or discomfort, bloating, and chronic constipation.

Inclusion Criteria:

• Confirmed constipation-predominant irritable bowel syndrome (on the basis of Rome III criteria) (≥ 25 % lumpy or hard stools and ≤ 25 % mushy or watery stools).
• Meeting Rome III criteria for the determination of irritable bowel syndrome in the last 6 months prior to inclusion and the presence of symptoms such as abdominal pain, bloating and general digestive discomfort at least twice a week in the last 3 months prior to inclusion.
• Colonoscopy in the last 7 years prior to inclusion with normal results.

Exclusion Criteria:

• Diarrhoea-predominant irritable bowel syndrome (≥ 25 % mushy or watery stools and ≤ 25 % lumpy or hard stools).
• Clinical signs of alarm, such as rectorrhagia, fever, recent unexplained weight loss.
• Organic gastrointestinal diseases, including chronic inflammatory bowel disease and systemic diseases with gastrointestinal difficulties.
• Severe abdominal pain and the taking of analgesics or antispasmodics for the previous 5 days or more.
• Having begun treatment with psychotropic medicines or other drugs for the treatment of irritable bowel syndrome within the previous month.
• Dietary habits that could influence the assessment of the investigational product, such as slimming or a vegetarian diet.
• Known allergy to ingredient(s) in the investigational product.
• Known medical or psycho-physical condition that is, in the opinion of the investigator, in conflict with consumption of the investigational product and/or the course of the study.
• Participation in another clinical study less than one month before inclusion or concurrent participation in another clinical study.