Self-reported calcium intake and bone mineral content in children and adolescents

Objective: We examined the relationship between self-reported calcium (Cal intake and bone mineral content (BMC) in children and adolescents. We hypot hesized that an expression of Ca adjusted for energy intake (El), i.e., Ca density, would be a better predictor of BMC than unadjusted Ca because of u nderreporting of EI. Methods: Data were obtained on dietary intakes (repeated 24-hour recalls) a nd BMC (by DEXA) in a cross-section of 227 children aged 8 to 17 years. Biv ariate and multivariate analyses were used to examine die relationship betw een Ca, Ca density, and the dependent variables total body BMC and lumbar s pine BMC. Covariates included were height, weight, bone area, maturity age, activity score and El. Results: Reported El compared to estimated basal metabolic rate suggested u nderreporting of El. Total body and lumbar spine BMC were significantly ass ociated with El, but not Ca or Ca density, in bivariate analyses. After con trolling for size and maturity, multiple linear regression analysis reveale d unadjusted Ca to be a predictor of BMC in males in the total body (p = 0. 08) and lumbar spine (p = 0.01). Unadjusted Ca was not a predictor of BMC a t either site in females. Ca density was not a better predictor of BMC at e ither site in males or females. Conclusions: The relationship observed in male adolescents in this study be tween Ca intake and BMC is similar to that seen in clinical trials. Ca dens ity did not enable us to see a relationship between Ca intake and BMC in fe males, which may reflect systematic reporting errors or that diet is not a limiting factor in this group of healthy adolescents.