The aim of the study is to collect data for the assessment of the Lactobacillus casei DG (Enterolactis plus®) effect on overall abdominal pain/discomfort, symptoms and gut microbiota composition in patients with Irritable Bowel Syndrome.

The aim of the study is to collect data for the assessment of the Lactobacillus casei DG (Enterolactis plus®) effect on overall abdominal pain/discomfort, symptoms and gut microbiota composition in patients with Irritable Bowel Syndrome. The investigators suppose that, due to the immunomodulatory action of probiotics, overall abdominal pain/discomfort and symptoms will improve, fecal Immunoglobulin A levels will change, pro-inflammatory cytokine levels will decrease and the production of regulatory cytokines as Interleukin 10 will improve following consumption of Lactobacillus casei DG (Enterolactis plus®).

Inclusion Criteria:

• Age > 18 years and ≤ 65 years.
• A positive diagnosis of Irritable Bowel Syndrome regardless of bowel habit (both males and females), according to Rome III criteria.
• Negative outcome of barium enema or left colonoscopy within the previous two years.
• Negative relevant additional screening or consultation whenever appropriate.
• Ability of conforming to the study protocol.

Exclusion Criteria:

• Presence of any relevant organic, systemic or metabolic disease (particularly significant history of cardiac, renal, neurological, psychiatric, oncology, endocrinology, metabolic or hepatic disease), or abnormal laboratory values that will be deemed clinically significant on the basis of predefined values.
• Ascertained intestinal organic diseases, including ascertained celiac disease or inflammatory bowel diseases (Crohn's disease, ulcerative colitis, diverticular disease, infectious colitis, ischemic colitis, microscopic colitis).
• Previous major abdominal surgeries.
• Active malignancy of any type, or history of a malignancy (patients with a history of other malignancies that have been surgically removed and who have no evidence of recurrence for at least five years before study enrolment are also acceptable).
• Untreated food intolerance such as ascertained or suspected lactose intolerance, as defined by anamnestic evaluation or, if appropriate, lactose breath test.
• Assumption of probiotics or topic and/or systemic antibiotic therapy during the last month.
• Systematical/frequent assumption of contact laxatives.
• Females of childbearing potential, in the absence of effective contraceptive methods.
• Pregnant women.
• Inability to conform with protocol.
• Treatment with any investigational drug within the previous 30 days.
• Recent history or suspicion of alcohol abuse or drug addiction.
• Previous participation in this study.