The Inside Study II: Oligosaccharides Versus Placebo and Hard Stools

Inclusion Criteria: * Written informed consent * aged 1-4 years * Hard and/or firm stools as scored by a stool questionnaire Exclusion Criteria: * Children that meet the Rome IV criteria for functional constipation * Children who suffer from any other GI complaints, known structural GI abnormalities, or previous GI surgery * Any condition that would make it unsafe for the child to participate. * Children with clinically significant cardiac, vascular, liver, pulmonary, psychiatric disorders, severe renal insufficiency, human immunodeficiency virus, acquired immunodeficiency syndrome, hepatitis B or C or known abnormalities of haematology, urinalysis, or blood biochemistry, as checked by the inclusion questionnaire. * Children who are allergic to cow's milk or fish * Use of antibiotics or other medicines or food supplements, and breast milkfeeding, which can influence defecation and gut microbiota 4 weeks prior to the study * Children that participate in another clinical trial