Following an application from Vivatech, submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of France, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to hydroxyanthracene derivatives and improvement of bowel function. An improvement of bowel function such as reduced transit time, more frequent bowel movements, increased faecal bulk, or softer stools is a beneficial physiological effect, provided that it does not result in diarrhoea. The Panel notes that the effect of hydroxyanthracene derivatives from the root and rhizome of Rheum palmatum L. and/or Rheum officinale Baillon and/or their hybrids, from the leaves or fruits of Cassia senna L. and/or Cassia angustifolia Vahl, from the bark of Rhamnus frangula L., from the bark of Rhamnus purshianus D.C. and from Aloe barbadensis Miller and/or various aloe species, mainly Aloe ferox Miller and its hybrids on the short-term alleviation of occasional constipation is well established. The Panel concludes that a cause and effect relationship has been established between consumption of hydroxyanthracene derivatives and improvement of bowel function.