Pubertal adolescents were randomly assigned to receive 8 g/d of a mixed short and long degree of polymerization inulin-type fructan product (fructan group) or maltodextrin placebo (control group). Bone mineral content and bone mineral density were mea sured before randomization and after 1 y. Calcium absorption was measured with the use of stable isotopes at baseline and 8 weeks and 1 year after supplementation.Polymorphisms of the Fok 1 vitamin Dreceptor gene were determined.