Background: Low vitamin D concentrations among children and adolescents at northern latitudes are frequently observed. Also, inverse associations between 25-hydroxyvitamin D (25(OH)D) and PTH concentrations have been found in children of different ages. More studies on the link between vitamin D status and childhood bone health are needed.
Objective: To evaluate the status of serum 25(OH)D in autumn and the association between 25(OH)D concentrations and bone health in 781 healthy 811 years old Danish children (55°N).
Methods: A cross-sectional analysis was performed using baseline data from the optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) School Meal Study, including 3rd and 4th graders from nine public schools. In autumn 2011, fasting blood samples were drawn and serum 25(OH)D and intact PTH analysed. Background interviews were conducted and anthropometry, puberty stage, intake of dietary supplements and physical activity was measured. Whole body DXA scans were performed and total body less head (TBLH) DXA values were used in data analyses.
Results: Serum 25(OH)D ranged from 15.2 to 132 nmol/l, with mean of 60.7±18.7 nmol/l. Twenty-six percent of the children had concentrations between 25 and 50 nmol/l, while 2.4% had concentrations <25 nmol/l. Intake of dietary supplements ≥4 days/week (n=305) was associated with higher serum 25(OH)D (P<0.001). Girls had significantly lower 25(OH)D (P<0.001), and significantly higher iPTH (P=0.012) concentrations than boys. Serum 25(OH)D was inversely associated with iPTH without, and with, adjustment for age, gender, pubertal stage, month and ethnicity (P<0.001). No significant associations were found between serum 25(OH)D and bone mineral content (BMC) without, nor with, adjustment for bone area (BA), age, height, weight, gender, pubertal stage, ethnicity and physical activity. Likewise, no associations were found between serum 25(OH)D and BA or BMD.
Conclusion: A substantial number of Danish children did not reach the recommended level of 25(OH)D (>50 nmol/l) during autumn. Despite a significant association with iPTH, no overt association between serum 25(OH)D and bone health was established.
The OPUS project (optimal well-being, development and health for Danish children through a healthy New Nordic Diet) is supported by a grant from the Nordea Foundation.
22 - 25 Jun 2013