Body mass but not vitamin D status is associated with bone mineral content and density in
young school children in northern Sweden
Sammanfattning
Background: High latitude of residence where sun exposure is limited affects vitamin D status.
Although vitamin D levels have been associated with poor bone health, cut-off values for optimising
bone health are yet to be decided.
Objective: To assess vitamin D intake and status among young school children living at latitude 63-
64 °N, in northern Sweden and to examine the association between vitamin D status and bone
mineral content (BMC) and bone mineral density (BMD).
Design: In a cross-sectional study, diet was assessed by a 4-day food diary and a food frequency
questionnaire in 8- to 9-year-old children (n=120). Energy, vitamin D, and calcium intakes were
calculated. Physical activity was assessed using a pedometer for 7 days. Serum 25-hydroxyvitamin
D (S-25[OH]D) levels were analysed by high-pressure liquid chromatography-atmospheric pressure
chemical ionisation-mass spectrometry (n=113). BMC and BMD were assessed by dual energy X-ray
absorptiometry scan. Height and weight were measured by standard procedures and BMI z-score
was calculated using WHO AnthroPlus programme.
Results: The majority of children, 91%, did not reach the recommended vitamin D intake of 7.5 µg/day
and 50% had insufficient S-25[OH]D levels defined as <50 nmol/l. The highest concentrations of S-25
[OH]D were observed during the summer months (p=0.01). Body mass (p<0.01) but not S-25[OH]D
was associated with measures of BMC and BMD. Furthermore, boys had higher total BMC (p=0.01),
total body less head BMC (p=0.02), fat free mass (p<0.01), and a higher degree of physical activity
(p=0.01) compared to girls.
Conclusions: Body mass was related to BMC and BMD measures in a population of prepubertal
school children living at high latitudes in Sweden. Despite insufficient S-25[OH]D levels and low
vitamin D intake, this did not appear to affect bone parameters. Prospective studies with repeated
assessment of vitamin D status are needed to examine cut-off values for optimising bone health.