title: High dose dietary vitamin D3increases bone mass and strength in mice.
abstract: Vitamin D plays a critical role in skeletal homeostasis. Vitamin D supplementation is used worldwide to maintain optimal bone health, but the most appropriate level of supplementation remains controversial. This study aimed to determine the effects of varying doses of dietary vitamin D3on the mechanical properties and morphology of growing bone. Eight-week-old female mice were supplied with one of 3 diets, each containing a different dose of vitamin D3: 1000 IU/kg (control), 8000 IU/kg or 20,000 IU/kg. Mice hadad libitumaccess to the specialty diet for 4 weeks before they were culled and their tibiae collected for further analysis. The collected tibia underwent three-point bending and reference-point indentation from which their mechanical properties were determined, and cortical and trabecular morphology determined by micro computed tomography. Dietary supplementation with 20,000 IU/kg vitamin D3resulted in greater ductility (~ 200%) and toughness (~ 150%) compared to the 1000 IU/kg control. The 20,000 IU/kg diet was also associated with significantly greater trabecular bone volume fraction and trabecular number. The 8000 IU/kg diet had no significant effect on trabecular bone mass. We conclude that vitamin D3supplementation of 20,000 IU/kg during early adulthood leads to tougher bone that is more ductile and less brittle than that of mice supplied with standard levels of dietary vitamin D3(1000 IU/kg) or 8000 IU/kg. This suggests that dietary vitamin D3supplementation may increase bone health by improving bone material strength and supports the use of vitamin D3supplementation, during adolescence, for achieving a higher peak bone mass in adulthood and thereby preventing osteoporosis.
authors.affiliation: Department of Medicine, St. Vincent's Hospital Melbourne, The University of Melbourne, Melbourne, VIC 3065, Australia.
authors.forename: Liam
authors.initials: L
authors.lastname: Williamson
authors.affiliation: Institute for Sport, Exercise and Active Living (ISEAL), College of Health and Biomedicine, Victoria University, Melbourne, VIC 8001, Australia; Australian Institute for Musculoskeletal Science (AIMSS), Western Health, Melbourne, VIC 3021, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Hayes
authors.affiliation: Institute for Sport, Exercise and Active Living (ISEAL), College of Health and Biomedicine, Victoria University, Melbourne, VIC 8001, Australia; Department of Exercise & Sport Science, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Erik D
authors.initials: ED
authors.lastname: Hanson
authors.affiliation: St Vincent's Department of Surgery, The University of Melbourne, Melbourne, VIC 3065, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Pivonka
authors.affiliation: Department of Medicine, St. Vincent's Hospital Melbourne, The University of Melbourne, Melbourne, VIC 3065, Australia; St. Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, VIC 3065, Australia.
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Sims
authors.affiliation: Department of Medicine, St. Vincent's Hospital Melbourne, The University of Melbourne, Melbourne, VIC 3065, Australia.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Gooi
keywords: 3 point bending; Bone strength; Cholecalciferol; Vitamin D3