title: Psychosocial factors influencing calcium intake and bone quality in middle school girls.
abstract: Calcium intake has been associated with promoting bone health in children and adolescents, thus preventing osteoporosis later in life. Behavior change such as increased calcium intake, as well as physiological factors such as bone quality, may be facilitated by psychosocial and environmental factors. The purpose of this study was to identify pathways by which psychosocial factors influence calcium intake and bone quality in middle school girls. The study design was cross-sectional. Baseline data from the Incorporating More Physical Activity and Calcium in Teens (IMPACT) study, collected in 2001-2003, were used. IMPACT was a 1.5-year nutrition and physical activity intervention study, designed to improve bone density in 717 middle school girls in Texas. Main outcome measures were calcium intake determined using mean milligrams of calcium consumed per day and number of glasses of milk consumed per day, and bone quality determined using a calcaneal stiffness index. Confirmatory factor analysis and path analysis were performed to identify the direct and indirect pathways used by various psychosocial factors such as knowledge, self-efficacy, outcome expectations, and milk availability at home, to influence calcium intake and bone quality. Results showed that knowledge of osteoporosis and calcium-rich foods had an indirect effect on calcium intake, with outcome expectations as the mediating variable (beta=.035 and beta=.03, respectively; P<0.05). Calcium self-efficacy had a significant indirect effect on calcium intake, with outcome expectations as the mediator (beta=.085, P<0.05). None of the variables significantly influenced bone quality. Thus, several direct and indirect pathways used to influence calcium intake among adolescent girls were identified. These findings are critical for the development of effective interventions to promote calcium intake in this population.
authors.affiliation: Michael and Susan Dell Center for the Advancement of Healthy Living, School of Public Health, The University of Texas Health Science Center at Houston, 1200 Herman Pressler, E RAS 603, Houston, TX 77030, USA. Shreela.V.Sharma@uth.tmc.edu
authors.forename: Shreela V
authors.initials: SV
authors.lastname: Sharma
authors.forename: Deanna M
authors.initials: DM
authors.lastname: Hoelscher
authors.forename: Steven H
authors.initials: SH
authors.lastname: Kelder
authors.forename: Pamela
authors.initials: P
authors.lastname: Diamond
authors.forename: R Sue
authors.initials: RS
authors.lastname: Day
authors.forename: Albert
authors.initials: A
authors.lastname: Hergenroeder
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D017195:Adolescent Nutritional Physiological Phenomena / Q000502:physiology*; D000818:Animals; D015519:Bone Density / Q000187:drug effects* / Q000502:physiology; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D002648:Child; D053198:Child Nutrition Sciences / Q000193:education*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology* / Q000523:psychology; D005163:Factor Analysis, Statistical; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008892:Milk; D010024:Osteoporosis / Q000517:prevention & control / Q000523:psychology; D000297:Psychology, Adolescent; D020377:Self Efficacy; D012931:Social Environment
chemical_list: D050071:Bone Density Conservation Agents; D002136:Calcium, Dietary