Adequate dietary intake during the growth period is critical for bone mineral accretion. In 1997, an adequate intake (AI) of 1300 mg/d Ca was set for North American adolescents aged 9–18 years based on best available data. We determined bone Ca accrual values from age 9 to 18 years taking into account sex and maturity. Furthermore, we used the accrual data to estimate adolescents' Ca requirements. Total body bone mineral content (TBBMC) of eighty-five boys and sixty-seven girls participating in the Saskatchewan Paediatric Bone Mineral Accrual Study were used to determine annual TBBMC accumulation over the pubertal growth period. Using a similar factorial approach as the AI, we estimated Ca requirements of adolescent boys and girls for two age groups: 9–13 and 14–18 years. Between 9 and 18 years, boys accrued 198·8 (sd 74·5) g bone mineral content (BMC) per year, equivalent to 175·4 (sd 65·7) mg Ca per d with the maximum BMC accrual of 335·9 g from age 13 to 14 years. Girls had 138·1 (sd 64·2) g BMC per year, equalling121·8 (sd 56·6) mg Ca per d with the maximum annual BMC accrual of 266·0 g from age 12 to 13 years. Differences were observed between both sex and age groups with respect to Ca needs: boys and girls aged 9–13 years would require 1000–1100 mg/d Ca, and from age 14 to 18 years, the mean Ca requirements would be relatively stable at 1000 mg/d for girls but would rise to 1200 mg/d for boys.
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