title: Rates of bone loss in postmenopausal women randomly assigned to one of two dosages of vitamin D.
abstract: We conducted a study to determine whether increasing vitamin D intake above the recommended dietary allowance (RDA) of 5.0 micrograms (200 IU)/d reduces bone loss in healthy postmenopausal women residing at latitude 42 degrees N. In this double-blind, randomized 2-y trial, we enrolled 247 healthy ambulatory postmenopausal women who consumed an average of 2.5 micrograms (100 IU) vitamin D/d in their usual diets. The women were given either 2.5 micrograms (100 IU) or 17.5 micrograms (700 IU) vitamin D/d. All women received 500 mg supplemental calcium per day as citrate malate. Duplicate hip and spine and single whole-body scans were performed by dual-energy x-ray absorptiometry at 6-mo intervals selected to flank the periods when 25-hydroxycholecalciferol (calcidiol) concentrations are highest (summer/fall) and lowest (winter/spring). Plasma calcidiol and serum osteocalcin were measured in these seasons in year 1. Both treatment groups lost bone mineral density from the femoral neck, but the 17.5-micrograms group lost less than (-1.06 +/- 0.34%; mean +/- SE) the 2.5-micrograms group (-2.54 +/- 0.37%, P = 0.003). Seventy percent of the benefit each year occurred in winter/spring and 30% in summer/fall. Changes in spinal and whole-body bone densities did not differ by treatment group and were minimal after 2 y. Serum osteocalcin and plasma calcidiol (2.5-micrograms group only) fluctuated with season. In conclusion, in healthy, calcium-supplemented, postmenopausal women residing at latitude 42 degrees N, an intake of 5.0 micrograms (200 IU) vitamin D/d is sufficient to limit bone loss from the spine and whole body but it is not adequate to minimize bone loss from the femoral neck.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA.
authors.forename: B
authors.initials: B
authors.lastname: Dawson-Hughes
authors.forename: S S
authors.initials: SS
authors.lastname: Harris
authors.forename: E A
authors.initials: EA
authors.lastname: Krall
authors.forename: G E
authors.initials: GE
authors.lastname: Dallal
authors.forename: G
authors.initials: G
authors.lastname: Falconer
authors.forename: C L
authors.initials: CL
authors.lastname: Green
mesh_terms: D000368:Aged; D015519:Bone Density / Q000187:drug effects; D001842:Bone and Bones / Q000378:metabolism; D002112:Calcifediol / Q000097:blood; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005272:Femur Neck / Q000503:physiopathology; D006801:Humans; D008875:Middle Aged; D009751:Nutritional Requirements; D015675:Osteocalcin / Q000097:blood; D015663:Osteoporosis, Postmenopausal / Q000178:diet therapy / Q000503:physiopathology* / Q000517:prevention & control*; D012621:Seasons; D013131:Spine / Q000503:physiopathology; D014807:Vitamin D / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D015675:Osteocalcin; D014807:Vitamin D; D002112:Calcifediol