title: Racial differences in bone turnover and calcium metabolism in adolescent females.
abstract: Blacks develop a higher peak bone mass than whites which is associated with a reduced risk for bone fracture. The physiological basis for the difference in bone mass was investigated by metabolic balance and calcium kinetic studies in adolescent black and white girls. The hypothesis that the greater peak bone mass in blacks compared with whites is due to suppressed bone resorption was tested. Subjects were housed in a supervised environment for 3 wk during which time they consumed a controlled diet and collected all excreta. Subjects were given stable calcium isotopes orally and intravenously after 1 wk adaptation. Blacks have greater calcium retention (mean +/- SD, 11.5 +/- 6.1 vs. 7.3 +/- 4.1 mmol/d, P < 0.05) consistent with greater bone formation rates (49.4 +/- 13.5 vs. 36.5 +/- 13.6 mmol/d, P < 0.05) relative to bone resorption rates (37.4 +/- 13.2 vs. 29.4 +/- 10.9 mmol/d, P = 0.07), increased calcium absorption efficiency (54 +/- 19 vs. 38 +/- 18%, P < 0.05) and decreased urinary calcium (1.15 +/- 0.95 vs. 2.50 +/- 1.35 mmol/d, P < 0.001), compared with whites. The racial differences in calcium retention in adolescence can account for the racial differences in bone mass of adults.
authors.affiliation: Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Bryant
authors.forename: M E
authors.initials: ME
authors.lastname: Wastney
authors.forename: B R
authors.initials: BR
authors.lastname: Martin
authors.forename: O
authors.initials: O
authors.lastname: Wood
authors.forename: G P
authors.initials: GP
authors.lastname: McCabe
authors.forename: M
authors.initials: M
authors.lastname: Morshidi
authors.forename: D L
authors.initials: DL
authors.lastname: Smith
authors.forename: M
authors.initials: M
authors.lastname: Peacock
authors.forename: C M
authors.initials: CM
authors.lastname: Weaver
mesh_terms: D000293:Adolescent; D044383:Black People; D015519:Bone Density; D016723:Bone Remodeling / Q000502:physiology*; D001862:Bone Resorption / Q000208:ethnology*; D002118:Calcium / Q000378:metabolism*; D005260:Female; D006801:Humans; D010012:Osteogenesis / Q000502:physiology; D044465:White People
chemical_list: D002118:Calcium