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 .
[Prevention of vitamin D deficiency in adolescents and pre-adolescents. An interventional multicenter study on the biological effect of repeated doses of 100,000 IU of vitamin D3].
UNLABELLED Recent studies have shown a high prevalence of calcium and vitamin D deficiencies in adolescents . The aim of this present study was to follow the changes in calcium status and 25 hydroxyvitamin D ( 25[OH]D ) and parathyroid hormone ( iPTH ) levels during winter in preadolescents and adolescents from four university hospitals in northern France . SUBJECTS AND METHODS Two groups of teenagers and adolescents ( range : 10 - 15 years ) were followed from October 1996 to June 1997 . They were given either 100,000 IU of vitamin D ( treated group n = 33 ) or a placebo ( control group n = 35 ) in October , January and April . Serum calcium , phosphate , 25(OH)D and iPTH levels were measured at inclusion and every three months thereafter . RESULTS At inclusion , plasma or serum 25(OH)D levels were < or = 10 ng/mL in 16 subjects and < 6 ng/mL in six . In control children , no significant change in 25(OH)D occurred during the study , while plasma or serum iPTH levels increased to 34 + /- 11 pg/mL. In the treated groups , 25(OH)D levels remained > 20 ng/mL in every subject ; no hypercalcemia was observed ; and the mean plasma or serum iPTH level was 25 + /- 14 pg/mL at the end of the study . CONCLUSION Teenagers presented with a high prevalence of biological vitamin D deficiency at the end of summer . The increase of iPTH during winter in the unsupplemented group suggests that this has secondary consequences on their calcium homeostasis unless they are supplemented with vitamin D. We advocate a sufficient calcium supply and a 100,000 IU vitamin D supplement given two or three times during winter to preadolescents and adolescents living in northern France
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 .