title: A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents.
abstract: BACKGROUND
  Short-term studies in adolescents have generally shown an enhancement of calcium absorption by inulin-type fructans (prebiotics). Results have been inconsistent; however, and no studies have been conducted to determine whether this effect persists with long-term use.
  
  
  OBJECTIVE
  The objective was to assess the effects on calcium absorption and bone mineral accretion after 8 wk and 1 y of supplementation with an inulin-type fructan.
  
  
  METHODS
  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 measured before randomization and after 1 y. Calcium absorption was measured with the use of stable isotopes at baseline and 8 wk and 1 y after supplementation. Polymorphisms of the Fok1 vitamin D receptor gene were determined.
  
  
  RESULTS
  Calcium absorption was significantly greater in the fructan group than in the control group at 8 wk (difference: 8.5 +/- 1.6%; P < 0.001) and at 1 y (difference: 5.9 +/- 2.8%; P = 0.04). An interaction with Fok1 genotype was present such that subjects with an ff genotype had the least initial response to fructan. After 1 y, the fructan group had a greater increment in both whole-body bone mineral content (difference: 35 +/- 16 g; P = 0.03) and whole-body bone mineral density (difference: 0.015 +/- 0.004 g/cm(2); P = 0.01) than did the control group.
  
  
  CONCLUSIONS
  Daily consumption of a combination of prebiotic short- and long-chain inulin-type fructans significantly increases calcium absorption and enhances bone mineralization during pubertal growth. Effects of dietary factors on calcium absorption may be modulated by genetic factors, including specific vitamin D receptor gene polymorphisms.
authors.affiliation: US Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, TX 77030, USA. sabrams@bcm.edu
authors.forename: Steven A
authors.initials: SA
authors.lastname: Abrams
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Griffin
authors.forename: Keli M
authors.initials: KM
authors.lastname: Hawthorne
authors.forename: Lily
authors.initials: L
authors.lastname: Liang
authors.forename: Sheila K
authors.initials: SK
authors.lastname: Gunn
authors.forename: Gretchen
authors.initials: G
authors.lastname: Darlington
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ellis
mesh_terms: D000042:Absorption; D000293:Adolescent; D015519:Bone Density; D002113:Calcification, Physiologic; D002118:Calcium / Q000378:metabolism*; D002648:Child; D005260:Female; D005630:Fructans / Q000008:administration & dosage*; D005838:Genotype; D006801:Humans; D007444:Inulin / Q000008:administration & dosage*; D008297:Male
chemical_list: D005630:Fructans; D007444:Inulin; D002118:Calcium