Following an application from Synbiotec S.r.l. submitted pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Italy, the Panel on Dietetic Products, Nutrition and Allergies was asked to deliver an opinion on the scientific substantiation of a health claim related to Synbio, a combination of Lactobacillus rhamnosus IMC 501® and Lactobacillus paracasei IMC 502®, and contribution to maintaining and improving intestinal well-being. The food constituent Synbio is sufficiently characterised. The Panel considers that maintenance or improvement of intestinal well-being by increasing intestinal regularity and faecal volume might be a beneficial physiological effect. The target population is healthy adults. The applicant identified 19 references to be pertinent to the health claim. These references included two published articles, one unpublished article, two references on patents, a PhD thesis, six unpublished technical reports on the strains added to different foods and seven communications to conferences. In weighing the evidence, the Panel considers that only one human study evaluated outcomes related to the claimed effect and that the weaknesses of this study (e.g. small sample size, effect of food matrices disregarded, inadequate questionnaire/scale used for measuring the outcomes, and lack of objective outcome measures) limit its value for the scientific substantiation of the claimed effect. The Panel concludes that a cause and effect relationship has not been established between the consumption of Synbio, a combination of Lactobacillus rhamnosus IMC 501® and Lactobacillus paracasei IMC 502®, and contribution to maintaining and improving intestinal well-being by increasing intestinal regularity and faecal volume.