| Summary: | Summary Little is known about the prevalence of actual
vitamin D deficiency in healthy school-aged adolescents, particularly
in China. The aim of this study was to examine the
prevalence of hypovitaminosis D and to identify whether
there was any association between vitamin D status, body
composition and physical exercise in 323 Chinese adolescent
girls in Beijing, China (40°N).
Introduction It is well recognized that persistent severe
vitamin D deficiency is associated with the bone abnormalities
of rickets and osteomalacia. However, there is now
evidence suggesting that low vitamin D status, not previously
considered to be a state of deficiency is associated with
secondary hyperparathyroidism, increased bone remodelling
and other clinical signs thought only to be found in severe
vitamin D deficiency. Hypovitaminosis D in healthy children
and adolescents has been reported frequently in many
countries, especially in winter.
Methods We performed a cross-sectional analysis of 323
Chinese adolescent girls in Beijing in winter. Mean age of the
subjects was 15.0 (±0.4) years. About 32.8%, 68.4% and
89.2% of the subjects were at risk of vitamin D deficiency
when defined as plasma concentrations of 25(OH)D of 25,
37.5 or 50 nmol/L, respectively.
Results This cross-sectional analysis of 323 Chinese adolescent
girls in Beijing in winter showed that hypovitaminosis D
was common in these subjects. In addition, body mass index,
milk intake, participation in organized sports and total
physical activity were all significant independent determinants
of vitamin D status. An inverse association was found
between plasma 25(OH)D and intact-parathyroid hormone
(iPTH) concentration. Body mass index (BMI), milk intake,
participation in organized sports and total physical activity all
emerged as major independent determinants of vitamin D
status as assessed by plasma 25(OH)D concentration. Vitamin D
status was positively associated with lean body mass (LBM),
but there was no association with the degree of body adiposity.
Regardless of the concentration of 25(OH)D in blood used to
define vitamin D deficiency, hypovitaminosis D was common
in these subjects.
Conclusion It is recommended that policies be developed to
prevent vitamin D deficiency in adolescent girls. Further
studies are needed to identify the mechanisms whereby
vitamin D status is related to exercise and to body composition
during growth.
|
|---|