ABSTRACT
Controversy persists concerning the impact of community water fluoridation on bone health in adults, and few studies have assessed relationships with bone at younger ages. Ecological studies of fluoride's effects showed some increase in bone mineral density of adolescents and young adults in areas with fluoridated water compared with non-fluoridated areas. However, none had individual fluoride exposure measures. To avoid ecological fallacy and reduce bias, we assessed associations of average daily fluoride intake from birth to age 15 yr for Iowa Bone Development Study cohort members with age 15 yr dual-energy x-ray absorptiometry (DXA) bone outcomes (whole body, lumbar spine, and hip), controlling for known determinants (including daily calcium intake, average daily time spent in moderate-to-vigorous intensity physical activity, and physical maturity). Mean (SD) daily fluoride intake was 0.66 mg (0.24) for females and 0.78 mg (0.30) for males. We found no significant relationships between daily fluoride intake and adolescents' bone measures in adjusted models (for 183 females, all p values ≥ .10 and all partial R(2) ≤ 0.02; for 175 males, all p values ≥ .34 and all partial R(2) ≤ 0.01). The findings suggest that fluoride exposures at the typical levels for most US adolescents in fluoridated areas do not have significant effects on bone mineral measures.
Subject(s)
Bone and Bones/drug effects , Cariostatic Agents/therapeutic use , Fluorides/therapeutic use , Absorptiometry, Photon , Adolescent , Body Height , Body Weight , Bone Density/drug effects , Bone Development/drug effects , Calcium, Dietary/administration & dosage , Cariostatic Agents/administration & dosage , Cohort Studies , Female , Fluorides/administration & dosage , Growth , Humans , Longitudinal Studies , Lumbar Vertebrae/drug effects , Male , Motor Activity , Pelvic Bones/drug effects , Prospective Studies , Vitamin D/administration & dosage , Vitamins/administration & dosageABSTRACT
OBJECTIVE: This study compared accelerometry to self-report for the assessment of physical activity (PA) in relation to bone mineral content (BMC). In addition, we compared the ability of these measures to assess PA in boys versus girls. METHODS: Participants in this cross-sectional study included 449 children (mean age 11 years) from the Iowa Bone Development Study. PA was measured via 3-5 days of accelerometry using the Actigraph and 7 day self-report questionnaire using the Physical Activity Questionnaire for Children (PAQ-C). Hip, spine, and whole body BMC were measured via dual energy x ray absorptiometry (DXA). RESULTS: Partial correlation analysis (controlling for height, weight, and maturity) showed the Actigraph was significantly associated with hip (r = 0.40), spine (r = 0.20), and whole body (r = 0.33) BMC in boys, as was the PAQ-C (r = 0.28 hip, r = 0.19 spine, and r = 0.22 whole body). Among girls, only the Actigraph was significantly associated with hip (r = 0.18) and whole body (r = 0.16) BMC. Both the Actigraph and PAQ-C were significant in hip, spine, and whole body multivariable linear regression models (after controlling for body size and maturity) in boys. Only the Actigraph entered hip BMC regression model in girls. CONCLUSIONS: Our study supports previous work showing associations between everyday PA and BMC in older children. These associations are more likely to be detected with an objective versus subjective measure of PA, particularly in girls.
