Following an application from Clasado Ltd., submitted pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of the United Kingdom, the Panel on Dietetic Products, Nutrition and Allergies was asked to deliver an opinion on the scientific substantiation of a health claim related to Bimuno® GOS and reducing gastro-intestinal discomfort. The food constituent that is the subject of the health claim, Bimuno® GOS, is sufficiently characterised. The claimed effect is reduction of gastro-intestinal discomfort, which is a beneficial physiological effect. The applicant identified eight human intervention studies, two human observational studies, and three non-human studies as being pertinent to the health claim. The Panel considers that owing to important methodological limitations, no conclusions with respect to the scientific substantiation of the claim can be drawn from the two human intervention studies which investigated the effect of Bimuno® GOS on symptoms related to gastro-intestinal discomfort. The remaining human studies, and the animal and in vitro studies, addressed the effects of either Bimuno® GOS or other galacto-oligosaccharides from a variety of sources on the gut microbiota. The Panel considers that the evidence provided does not establish that an effect of Bimuno® GOS on bifidobacteria per se is sufficient to predict an effect of Bimuno® GOS on gastro-intestinal discomfort in vivo in humans. The Panel considers that no human studies have been provided from which conclusions can be drawn for the scientific substantiation of the claim. The Panel concludes that a cause and effect relationship has not been established between the consumption of Bimuno® GOS and reducing gastro-intestinal discomfort. © European Food Safety Authority, 2011