Effect of Galacto-oligosaccharides (GOS) on Faecal Gut Microbiota in Adult Women

Inclusion Criteria: * Apparently healthy women * Aged between 40 - 70 year * Body Mass Index (BMI) between 18.5 - 30 kg/m2 Exclusion Criteria: * Having a gastro-intestinal disease, such as celiac disease, Crohn's disease, Ulcerative colitis, or diagnosed irritable bowel syndrome; * Having a history of intestinal surgery that might interfere with study outcomes. This does not include an appendectomy or cholecystectomy; * Diagnosed with diabetes mellitus; * Use of medication that may influence the study results, such as laxatives, lactase preparations, metformin, antibiotics, proton pomp inhibitors, antipsychotics, NSAID's (judged by our research physician); * Self-perceived and diagnosed constipation; * Having a food allergy to cow's milk or being lactose intolerant; * Self-reported slimming, medically prescribed or other diets * Reported weight loss or weight gain of \>5kg in the month prior to screening * Use of (foods with) pre-, pro-, syn- and/or postbiotics\* (should be stopped at least 4 weeks before the start of the study), or other supplements that can influence the study results (to be determined by the medical investigator); * History of side effects with the use of prebiotic supplements * Use of antibiotic treatment less than 3 months before start of the study * Pregnant or lactating (or having the wish to become pregnant during the study period, self-reported); * Not able to comply with study procedures; * Use of drugs (should be stopped at least 4 weeks before the study); * Alcohol intake ≥7 glasses of alcoholic beverages per week, on average * Participation in another clinical trial at the same time; * Being an employee of the Food, Health \& Consumer Research group of Wageningen Food \& Biobased Research or employee of FrieslandCampina R\&D.