Vitamin D supplementation had no statistically significant effects on total body bone mineral content or on bone mineral density of the hip or forearm .
It is unlikely that vitamin D supplements are beneficial in children and adolescents with normal vitamin D levels .
OBJECTIVE To determine the effectiveness of vitamin D supplementation for improving  bone mineral density in children and adolescents and if effects vary with factors such as vitamin D dose and vitamin D status .
Season and ethnicity are determinants of serum 25-hydroxyvitamin D concentrations in New Zealand children aged 5-14 y.
New Zeal and children , particularly those of Māori and Pacific ethnicity , may be at risk for low vitamin D status because of low vitamin D intakes , the country 's latitude ( 35 - 46 degrees S ) , and skin color . The aim of this study was to determine 25-hydroxyvitamin D concentrations and their determinants in a national sample of New Zeal and children aged 5 - 14 y. The 2002 National Children 's Nutrition Survey was design ed to survey New Zeal and children , including oversampling of Māori and Pacific children to allow ethnic-specific analyses . A 2-stage recruitment process occurred using a r and om selection of schools , and children within each school .  Serum 25-hydroxyvitamin D concentration [ mean ( 99 % CI ) nmol/L ] in Māori children ( n = 456 ) was 43 ( 38,49 ) , in Pacific ( n = 646 ) 36 ( 31,42 ) , and in New Zeal and European and Others ( NZEO ) ( n = 483 ) 53 ( 47,59 ) . Among Māori , Pacific , and NZEO , the prevalence ( % , 99 % CI ) of serum 25-hydroxyvitamin D deficiency ( < 17.5 nmol/L ) was 5 ( 2,12 ) , 8 ( 5,14 ) , and 3 ( 1,7 ) , respectively . The prevalence of insufficiency ( < 37.5 nmol/L ) was 41 ( 29,53 ) , 59 ( 42,75 ) , and 25 ( 15,35 ) , respectively . Multiple regression analysis found that 25-hydroxyvitamin D concentrations were lower in winter than summer [ adjusted mean difference ( 99 % CI ) nmol/L ; 15 ( 8,22 ) ] , lower in girls than boys [ 5 ( 1,10 ) ] , and lower in obese children than in those of " normal " weight [ 6 ( 1,11 ) ] . Relative to NZEO , 25-hydroxyvitamin D concentrations were lower in Māori [ 9 ( 3,15 ) ] and Pacific children [ 16 ( 10,22 ) ] . Ethnicity and season are major determinants of serum 25-hydroxyvitamin D. There is a high prevalence of vitamin D insufficiency in New Zeal and children , which may or may not contribute to increased risk of osteoporosis and other chronic disease . There is a pressing need for more convincing evidence concerning the health risks associated with the low  vitamin D status in New Zeal and children
Vitamin D supplementation had no statistically significant effects on total body bone mineral content or on bone mineral density of the hip or forearm .
It is unlikely that vitamin D supplements are beneficial in children and adolescents with normal vitamin D levels .
OBJECTIVE To determine the effectiveness of vitamin D supplementation for improving  bone mineral density in children and adolescents and if effects vary with factors such as vitamin D dose and vitamin D status .