To assess the effect of L. casei DG® (Lactobacillus paracasei CNCMI1572; Enterolactis® plus) on abdominal symptoms and gut microbiota metabolism/composition in non constipated patients with IBS (Irritable Bowel Syndrome). Patients will be randomized to receive L. casei DG® capsules, b.i.d. for 12 weeks the a 4 weeks Follow Up period will follow.

Inclusion Criteria:

• Age > 18 years and ≤ 65 years

• A positive diagnosis of non constipated IBS (i.e., IBS-D and IBS-M, both males and females), according to Rome IV criteria.

• A negative outcome of colonoscopy performed within 5 years before screening if patient is at least 50 years old, or if patient meet any of the following alarm features:

  1. Has a documented weight loss within the past 6 months; or
  2. Has nocturnal symptoms; or
  3. Has a familiar history of colon cancer; or
  4. Has blood mixed with their stool (excluding blood from hemorroids).

• Negative relevant additional screening or consultation whenever appropriate

• Ability to conform to the study protocol.

Exclusion Criteria:

• Patients with IBS-C or IBS-U according to Rome IV 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, (i.e..liver or kidney functional levels 2-times greater than the upper reference values)
• Ascertained intestinal organic diseases, including celiac disease, food allergies or inflammatory bowel diseases (Crohn's disease, ulcerative colitis, diverticular disease, infectious colitis, ischemic colitis, microscopic colitis).
• Previous major abdominal surgery.
• 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.
• Use of probiotics or topical and/or systemic antibiotic therapy during the last month.
• Systematic/frequent use of contact laxatives.
• Pregnant females or females of childbearing potential in the absence of effective contraceptive methods.
• Inability to conform to protocol.
• Treatment with any investigational drug within the previous 30 days.
• Recent history or suspicion of alcohol abuse or drug addiction.
• Presence of red or white flags at the Rome IV Psychosocial Alarm Questionnaire for Functional gastrointestinal Disorders.