Body composition and intake of nutrients associated with bone metabolism in young adolescents in a peri-urban setting

Objective: The aim was to describe the anthropometry, bone mineral content (BMC), bone mineral density (BMD), dietary calcium intake and 25(OH)D3 levels in 11- and 12-year-old children in a peri-urban area. Design: A cross-sectional, descriptive study in the quantitative domain was undertaken. Setting: Bronkhorstspruit, Gauteng, South Africa. Subjects: Children, conveniently selected, were assessed in two groups. The first group comprised 70 children. From the 70 children, 20 children were conveniently selected to form a sub-sample (n = 20). Outcome measures: Anthropometric data (weight, height) and dietary data (three quantified /multi-pass 24-hour recalls). Children in the sub-sample additionally underwent body composition assessment (dual-energy X-ray absorptiometry; DXA scan) and a finger prick for 25(OH)D3. Results: BMI and body composition data (body fat mass and lean fat mass) showed that the girls exceeded the boys in all measurements. The girls had a non-significantly higher BMD and BMC than the boys. The mean and median values for 25(OH)D3 were lower than the reference range values. Dietary intake results showed that the children had a sufficient macronutrient intake, but a deficient intake of calcium, phosphate and vitamin D. The sub-sample had a mean vitamin D intake of 3.2 mcg. Conclusion: The girls exceeded the boys in all the anthropometric and body composition measurements. The calcium and vitamin D intake of the children were of concern. There were no significant differences or relationships in the bone measurements and vitamin D status between the boys and girls.