Inclusion Criteria:  Age 8-18 years Any sex ROME IV diagnostic criteria Pediatric functional digestive disorders: in children and adolescents. H2. Functional abdominal pain disorders H2a. Functional dyspepsia H2b. Irritable bowel syndrome H2d. Functional abdominal pain not otherwise specified H3. Functional defecation disorders H3a. Functional constipation H3b. Non-retentive fecal incontinence Meet the criteria during the last three months with the onset symptoms for at least six months before diagnosis IBS rated moderate to severe according to GSRS-IBS score (Spanish / LA) At least two episodes of abdominal pain per week No consumption of probiotics at least two weeks before baseline measurements (but preferably four weeks); Dad, Mom, or Guardian able to understand the protocol; Be willing to maintain stable dietary habits throughout the study period; Be able to communicate well with the Investigator, to understand and comply with the requirements of the study and be judged suitable for the study in the opinion of the Investigator; Signature of Informed Consent.  Exclusion Criteria:  Children with systemic, organic or metabolic diseases, immunosuppression, different from IBS Previous major abdominal surgery; Consumption of proton pump inhibitors, H2 antagonists; Consumption of probiotics in the two weeks before baseline measurements; Are less than 8 or older than 18 years of age at the time of consent; Subject who has been on antibiotics during the past 3 months; Subjects who have not had at least two episodes of abdominal pain per week; Subject with a malignant disease or any concomitant end-state organ disease and/or laboratory abnormalities considered by Investigators to be risky or that could interfere with data collection; Subject who are coeliac or lactose intolerant; Known allergy to any of the components of the test product; Participation in a clinical study with an investigational product within 60 days before screening, or plans to participate in another study during the study period; Subject has a history of non-compliance; Use of dietary supplements or other fermented foods that contain live bacteria. Pregnant or lactating females.