Inclusion criteria:
Definitive diagnosis of cystic fibrosis (CF): The child or adolescent must have a CF diagnosis confirmed by a specialist physician, with medical documentation including pancreatic insufficiency and fecal elastase less than 200 μg/g
Age between 6 and 13 years: Patients must fall within the study’s age range to allow assessment of growth and physical functioning.
Stable clinical condition: The child must be in a stable clinical state and must not have had an acute infection or hospitalization in the 4 weeks prior to the start of the study
Ability to participate in the study and complete questionnaires: The patient or parents must be able to accurately respond to questionnaires regarding quality of life, respiratory, and gastrointestinal symptoms.
Informed consent from parents or legal guardians: Participation in the study is only possible with written consent from the parents or legal guardian.
No use of similar probiotics in the past month: Patients must not have used other probiotic supplements in the 4 weeks prior to the study to ensure the effect of the study probiotic is accurately assessed.
Exclusion criteria:
Allergy or intolerance to probiotics: Patients who are allergic to Lactobacillus reuteri or other components of the supplement, or who experience severe adverse effects from probiotic consumption, will be excluded from the study
Severe chronic or underlying diseases unrelated to CF: Children who, in addition to CF, have severe chronic conditions (e.g., advanced heart, liver, or kidney failure) that could affect weight, appetite, or quality of life. Concurrent autoimmune diseases such as celiac disease or immunodeficiency disorders are also considered exclusion criteria
Concurrent use of other probiotics or supplements: Patients who use other probiotics, similar nutritional supplements, or medications that directly affect gastrointestinal or respiratory symptoms of CF during the study.
Incomplete questionnaires or lack of follow-up: Children who do not complete the questionnaires fully or fail to participate in regular follow-ups over the two-month study period.
Acute infections or hospitalization during the study: Patients who are hospitalized or receive new inpatient treatments due to severe infections, as this could confound the effects of the probiotic.