title: Vitamin D intake is low and hypovitaminosis D common in healthy 9− to 15-year-old Finnish girls Randomized study of sunshine exposure and serum 25-OHD in breast-fed infants in Beijing, China. Factors affecting bone density in young adults. Season and ethnicity are determinants of serum 25-hydroxyvitamin D concentrations in New Zealand children aged 5-14 y. Effects of calcium, dairy product, and vitamin D supplementation on bone mass accrual and body composition in 10-12-y-old girls: a 2-y randomized trial. Double Blind Study on the Need for Vitamin D Supplementation in Prepubertal Children Vitamin D supplementation during infancy is associated with higher bone mineral mass in prepubertal girls. Effect of vitamin D supplementation on bone and vitamin D status among Pakistani immigrants in Denmark: a randomised double-blinded placebo-controlled intervention study. Wintertime Vitamin D Deficiency in Male Adolescents: Effect on Parathyroid Function and Response to Vitamin D3 Supplements Seasonal and geographical variations in the growth rate of infants in China receiving increasing dosages of vitamin D supplements. ED-71, a new active vitamin D3, increases bone mineral density regardless of serum 25(OH)D levels in osteoporotic subjects A positive dose-response effect of vitamin D supplementation on site-specific bone mineral augmentation in adolescent girls: a double-blinded randomized placebo-controlled 1-year intervention. School-milk intervention trial enhances growth and bone mineral accretion in Chinese girls aged 10-12 years in Beijing. Effect of vitamin D replacement on musculoskeletal parameters in school children: a randomized controlled trial. Bone density at various sites for prediction of hip fractures [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].
abstract: Objectives : To study the prevalence of hypovitaminosis D , the effect of vitamin D supplementation on serum 25-hydroxyvitamin D [ S-25(OH)D ] , and the intakes of vitamin D and calcium in Finnish 9− to 15-year-old athletic and nonathletic girls . Design : 1-year follow-up study ( February 1997-March 1998 ) with three months of vitamin D supplementation ( 10 μg/d ) from October to January . Setting : Turku University Central Hospital , Finl and .Subjects : 191 female volunteers aged 9–15 y ( 131 athletes and 60 controls ) . Methods :  Vitamin D and calcium intakes were estimated by a four-day food recording and a semi-quantitative food frequency question naire ( FFQ ) . S-25(OH)D was followed by radioimmunoassay ( RIA ) . Results : At baseline the mean S-25(OH)D concentration was 33.9 nmol/l among all girls . In winter severe hypovitaminosis D ( S-25(OH)D<20 nmol/l ) occurred in 13.4 % of the participants and in 67.7 % S-25(OH)D was below 37.5 nmol/l . By the next summer the mean S-25(OH)D concentration was 62.9 nmol/l and in 1.6 % of the subjects it was below 37.5 nmol/l . The prevalence of severe hypovitaminosis D was not significantly reduced by three months of vitamin D ( 10 μg/d ) supplementation . At baseline , the mean intake of vitamin  D was 2.9 μg/d by food recording and 4.3 μg/d by FFQ . The mean calcium intake was 1256 mg/d and 1580 mg/d , respectively . The intakes of vitamin D and calcium remained unchanged during the follow-up period . The athletes consumed more calcium than nonathletic controls , whereas the intake of vitamin D was quite similar among both groups . The vitamin D intake by FFQ correlated with the S-25(OH)D concentration in wintertime ( r=0.28 , P<0.01 ) . Conclusion : Hypovitaminosis D is fairly common in growing Finnish girls in the wintertime , and three months of vitamin D supplementation with 10 μg/d was insufficient in preventing hypovitaminosis D. The daily dietary vitamin D intake was insufficient ( < 5 μg/d ) in the majority of participants , while the calcium intake was usually sufficient . Sponsorship : Supported by the Yrjö Jahnsson Foundation , The Turku University Foundation , and the Medical Research Foundation of the Turku University Central Hospital The hypothesis that breastfed infants in Beijing , China , have low vitamin D status and that sunshine exposure increases serum 25-hydroxyvitamin D ( 25-OHD ) concentrations was tested in a r and omized prospect i ve study involving 42 healthy infants 1 - 8 months of age . 24 controls were exposed to the usual amount of sunshine , while the 18 cases were provided with 2 hours of sunshine/day . All infants were being breastfed without vitamin D supplementation .  Serum 25-OHD concentrations at entry into the study ranged from 3 - 61 ng/ml and increased with age . 3 infants in each group were diagnosed as having rickets . Serum 25-OHD concentrations did not change significantly during the 2-month study period among controls , while serum 25-OHD values increased significantly in the experimental group . Final infant serum 25-OHD concentrations correlated with ultraviolet exposure scores ( p.001 ) . The estimate of ultraviolet score needed to maintain a serum 25-OHD of 11 ng/ml was 2.4 ( 24 minutes/day with only the face uncovered ) . Rickets has been reported in as many as 18 % of Chinese infants and seems to especially affect those 2 - 4 months of age . The fact that not all infants with rickets in this study had low 25-OHD concentrations suggests 2 possibilities : 1 ) not all rickets is necessarily related to a vitamin D deficiency , or 2 ) serum 25-OHD concentrations are not the best indicator of vitamin D status . The low serum 25-OHD concentrations in many Chinese infants may be related to low maternal milk vitamin D content result ing from the lack of vitamin D food fortification . Overall , these results suggest that the diet of breastfed Chinese infants should be supplemented with orally administered vitamin A 14-y follow-up of 581 children who took part in a r and omized controlled trial of the effect of a milk supplement on growth of children was conducted to investigate the supplement 's effect on adult bone mineral content ( BMC ) and density ( BMD ) . BMC and BMD of the nondominant forearm were measured by single-photon absorptiometry in 371 subjects ( 64 % ) aged 20 - 23 y , at a proximal site ( shaft of radius and ulna ) and at a distal site near the wrist .  BMC s and BMDs tended to be higher in the intervention group ( NS ) . Cross-sectionally , BMD was positively associated with body weight ( P less than 0.01 ) in both sexes ; inversely associated with alcohol consumption ( P less than 0.05 ) , and positively with manual occupation ( NS ) in men ; positively associated with current intakes of calcium ( P less than 0.05 ) , vitamin D ( P less than 0.01 ) , and sports activity during adolescence ( P less than 0.01 ) , and inversely with parity ( NS ) in women . In multiple linear-regression analysis body weight and sports activity during adolescence were stronger determinants of female BMD than was diet 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 BACKGROUND Little is known about the relative effectiveness of calcium supplementation from food or pills with or without vitamin D supplementation for bone mass accrual during the rapid growth period . OBJECTIVE The purpose was to examine the effects of both food-based and pill supplements of calcium and vitamin D on bone mass and body composition  in girls aged 10 - 12 y. DESIGN This placebo-controlled intervention trial r and omly assigned 195 healthy girls at Tanner stage I-II , aged 10 - 12 y , with dietary calcium intakes < 900 mg/d to 1 of 4 groups : calcium ( 1000 mg ) + vitamin D3 ( 200 IU ) , calcium ( 1000 mg ) , cheese ( 1000 mg calcium ) , and placebo . Primary outcomes were bone indexes of the hip , spine , and whole body by dual-energy X-ray absorptiometry and of the radius and tibia by peripheral quantitative computed tomography . RESULTS With the use of intention-to-treat or efficacy analysis , calcium supplementation with cheese result ed in a higher percentage change in cortical thickness of the tibia than did placebo , calcium , or calcium + vitamin D treatment ( P = 0.01 , 0.038 , and 0.004 , respectively ) and in higher whole-body bone mineral density than did placebo treatment ( P = 0.044 ) when compliance was > 50 % . With the use of a hierarchical linear model with r and om effects to control for growth velocity , these differences disappeared . CONCLUSIONS Increasing calcium intake by consuming cheese appears to be more beneficial for cortical bone mass accrual than the consumption of tablets containing a similar amount of calcium . Diverse patterns of growth velocity may mask the efficacy of supplementation in a short-term trial of children transiting through puberty ABSTRACT . Fifty‐one healthy prepubertal schoolchildren were followed for 13 months in a double blind study . Twenty‐four of them were supplemented with 400 IU of vitamin D2 5–7 times weekly , while 27 received a placebo . The children were examined in winter both at the beginning and at the end of the study , and in the middle of the study in autumn . Mean 25‐hydroxyvitamin D levels in the supplemented group were significantly higher than those in the placebo group both in autumn and in winter , when the study ended . The vitamin D supplementation did not , however , affect other vitamin D metabolites , serum calcium , albumin , inorganic phosphorus , parathyroid hormone concentrations or alkaline phosphatase activity . Moreover , the supplementation caused no alterations in the weight or height gain or bone mineral content of the distal radius of the children , and thus sub clinical rickets could not be shown The objective of this study was to determine whether vitamin D supplementation of breast-fed infants during the first year of life is associated with greater bone mineral content and /or areal bone mineral density ( aBMD ) in later childhood . The design was a retrospective cohort study . One hundred and six healthy prepubertal Caucasian girls ( median age , 8 yr ; range , 7 - 9 yr ) were classified as vitamin D supplemented or unsupplemented during the first year of life on the basis of a question naire sent to participating families and their pediatricians . Bone area ( square centimeters ) and bone mineral content ( grams ) were determined by dual energy x-ray absorptiometry at six skeletal sites . Vitamin D receptor ( VDR ) 3'-gene polymorphisms ( BsmI ) were also determined . The supplemented ( n = 91 ) and unsupplemented ( n = 15 ) groups were similar in terms of season of birth , growth in the first year of life , age , anthropometric parameters , and calcium intake at time of dual energy x-ray absorptiometry . The supplemented group had higher aBMD at the level of radial metaphysis ( mean + /- SEM , 0.301+/-0.003 vs. 0.283+/-0.008 ; P = 0.03 ) , femoral neck ( 0.638+/-0.007 vs. 0.584+/-0.021 ; P = 0.01 ) , and femoral trochanter ( 0.508+/-0.006 vs. 0.474+/-0.016 ; P = 0.04 ) . At the lumbar spine level aBMD values were similar ( 0.626+/-0.006 vs. 0.598+/-0.019 ; P = 0.1 ) . In a multiple regression model taking into account the effects of vitamin D supplementation , height , and VDR genotype on aBMD ( dependent variable ) , femoral neck aBMD remained higher by 0.045 g/cm2 in the supplemented group ( P = 0.02 ) . Vitamin D supplementation in infancy was found to be associated with increased aBMD at specific skeletal sites later in childhood in prepubertal Caucasian girls Severe vitamin D deficiency is common among Muslim immigrants . The dose necessary to correct the deficiency and its consequence for bone health are not known for immigrants . The aim was to assess the effect of relatively low dosages of supplemental vitamin D on vitamin D and bone status in Pakistani immigrants . This 1-year-long r and omised double-blinded placebo-controlled intervention with vitamin D3 ( 10 and 20 microg/d ) included girls ( 10.1 - 14.7 years ) , women ( 18.1 - 52.7 years ) and men ( 17.9 - 63.5 years ) of Pakistani origin living in Denmark . The main endpoints were serum 25-hydroxyvitamin D ( S-25OHD ) , parathyroid hormone , bone turnover markers and bone mass . The study showed that supplementation with 10 and 20 microg vitamin D3 per d increased S-25OHD concentrations similarly in vitamin D-deficient Pakistani women ( 4-fold ) , and that 10 microg increased S-25OHD concentrations 2-fold and 20 microg 3-fold in Pakistani men . S-25OHD concentrations increased at 6 months and were stable thereafter . Baseline S-25OHD concentrations tended to be lower in girls and women than in men ; females achieved about 46 nmol/l and men 55 nmol/l after supplementation . Serum intact parathyroid hormone concentrations decreased at 6 months , but there was no significant effect of the intervention on bone turnover markers and dual-energy X-ray absorptiometry measurements of the whole body and lumbar spine Abstract : The first part of this study consisted of an 18 month follow-up of the vitamin D status and parathyroid function in a group of 54 French male adolescents , aged from 13 to 16 years old and all pupils of a jockey training school . During the 18 month period four samplings were made , one every 6 months . The first was during September of the first year , the second and third during March and October of the second year , and the last in March of the third year . Therefore we had two main periods : summer and winter . The summer 25-hydroxyvitamin D ( 25(OH)D ) concentrations were higher ( 71.6 ± 19.9 and 52.4 ± 16.5 nmol/l ) than the winter ones ( 20.4 ± 6.9 and 21.4 ± 6.1 nmol/l ) . Conversely , the winter intact parathyroid hormone ( iPTH ) serum levels ( 4.18 ± 1.18 and 4.11 ± 1.35 pmol/l ) were higher than the summer ones ( 2.44 ± 0.82 and 2.71 ± 0.71 pmol/l ) . At the two winter time points the 25(OH)D concentrations were lower than 25 nmol/l ( 10 ng/ml ) in 72 % ( 2nd year ) and 68 % ( 3rd year ) of the adolescents . In the second part of the study we tried a vitamin D3 supplementation procedure design ed to maintain the 25(OH)D and iPTH postsummer serum levels throughout the winter . Pairs of male adolescents matched for height , weight and Tanner pubertal stage were r and omly assigned to either vitamin D3 supplementation ( 2.5 mg , i.e. , 100 000 IU ) administered orally at three specific periods ( end of September , November and January ) or no vitamin D3 treatment ( control subjects ) . Blood was collected just before the first intake of vitamin D3 and 2 months after the last intake ( March ) . The control subjects had blood drawn at the same time points . In the vitamin D3-treated subjects , the concentrations of 25 (OH)D ( 55.3 ± 11.5 nmol/l ) and of iPTH ( 3.09 ± 1.16 pmol/l ) in March and September ( 53.8 ± 12.3 nmol/l and 2.75 ± 1.26 pmol/l ) were not significantly different . In the control subjects , March 25(OH)D levels ( 21.0 ± nmol/l were low , with values below 25 nmol/l in 78 % of subjects , and iPTH concentrations ( 3.97 ± 1.08 pmol/l ) were significantly ( p<0.001 ) higher than in September ( 2.91 ± 0.81 pmol/l ) . The constant vitamin D wintertime deficiency and wintertime rise in iPTH in adolescent French males throughout puberty has been demonstrated . In adolescents with low dairy calcium intakes , the vitamin D3 treatment was sufficient to maintain 25(OH)D concentrations at their summer levels throughout winter and to prevent an excessive wintertime rise in iPTH levels In theory , sunshine exposure is sufficient to maintain normal vitamin D concentrations for the optimal growth of newborn infants . To determine whether season of birth , latitude ( north v. south ) and increasing dosages of vitamin D supplements would influence the growth rate for the first 6 months of life , 255 healthy fall- and spring-born infants from two northern and two southern cities in China were r and omly assigned to receive either 100 , 200 , or 400 IU of vitamin D a day . The study showed that season of birth and dose of vitamin D did not affect the growth rate of infants born in the same latitude , but a significant difference was found in the gain in length over the 6-month period between infants from the north and infants from the south ( P = 0.0001 ) . Regional differences among the Chinese people , other than sunshine exposure , may have influenced the difference in length gain A previous r and omized placebo-controlled double-blinded clinical trial revealed that treatment of osteoporotic subjects supplemented with 200 or 400IU/day vitamin D3 with 0.75 microg/day ED-71 for 12 months increased lumbar and hip bone mineral density ( BMD ) by 3.4 and 1.5 % , respectively , compared to placebo group ( JCE&M 90:5031,2005 ) . These effects on BMD were stronger than any previous results using 1alpha(OH)D3 or 1,25(OH)2D3 . However , there still was a concern that the effect of ED-71 could be observed because serum 25(OH)D in many of these subjects were below its optimal level . In order to address this issue , we performed post hoc analysis to compare the effect of ED-71 on lumbar and hip BMD between subjects with upper ( > 29 ng/mL ) and lower tertiles ( < 25 ng/mL ) of serum 25(OH)D.  Lumbar BMD after 12-month treatment with 0.5 , 0.75 and 1.0 microg/day ED-71 increased similarly in both lower and upper tertile groups of serum 25(OH)D. In addition , hip BMD also showed a tendency to increase when 0.75 and 1.0 microg/day ED-71 groups were combined together in both upper and lower serum 25(OH)D tertile groups , although the increase was not statistically significant . These results demonstrate that the effect of ED-71 on bone is independent of supplementary effect for nutritional vitamin D insufficiency , and suggest that ED-71 may exert its effect as a unique VDR lig and with stronger effect on bone compared to the natural lig and , 1,25(OH)2D3 UNLABELLED The effect of vitamin D supplementation on bone mineral augmentation in 212 adolescent girls with adequate calcium intake was studied in a r and omized placebo-controlled setting . Bone mineral augmentation determined by DXA increased with supplementation both in the femur and the lumbar vertebrae in a dose-responsive manner . Supplementation decreased the urinary excretion of resorption markers , but had no impact on formation markers . INTRODUCTION Adequate vitamin D intake protects the elderly against osteoporosis , but there exists no indisputable evidence that vitamin D supplementation would benefit bone mineral augmentation . The aim of this 1-year study was to determine in a r and omized double-blinded trial the effect of 5 and 10 microg vitamin D3 supplementation on bone mineral augmentation in adolescent girls with adequate dietary calcium intake . MATERIAL S AND METHODS Altogether , 228 girls ( mean age , 11.4 + /- 0.4 years ) participated . Their BMC was measured by DXA from the femur and lumbar spine . Serum 25-hydroxyvitamin D [ S-25(OH)D ] , intact PTH ( S-iPTH ) , osteocalcin ( S-OC ) , and urinary pyridinoline ( U-Pyr ) and deoxypyridinoline ( U-Dpyr ) were measured . Statistical analysis was performed both with the intention-to-treat ( IT ) and compliance-based ( CB ) method . RESULTS In the CB analysis , vitamin D supplementation increased femoral BMC augmentation by 14.3 % with 5 microg and by 17.2 % with 10 microg compared with the placebo group ( ANCOVA , p = 0.012 ) . A dose-response effect was observed in the vertebrae ( ANCOVA , p = 0.039 ) , although only with the highest dose . The mean concentration of S-25(OH)D increased ( p < 0.001 ) in the 5-microg group by 5.7 + /- 15.7 nM and in the 10-microg group by 12.4 + /- 13.7 nM , whereas it decreased by 6.7 + /- 11.3 nM in the placebo group . Supplementation had no effect on S-iPTH or S-OC , but it decreased U-DPyr ( p = 0.042 ) . CONCLUSIONS Bone mineral augmentation in the femur was 14.3 % and 17.2 % higher in the groups receiving 5 and 10 microg of vitamin D , respectively , compared with the placebo group , but only 10 mug increased lumbar spine BMC augmentation significantly . Vitamin D supplementation decreased the concentration of bone resorption markers , but had no impact on bone formation markers , thus explaining increased bone mineral augmentation . However , the positive effects were noted with the CB method but not with IT A 2-year milk intervention trial was carried out with 757 girls , aged 10 years , from nine primary schools in Beijing ( April 1999 - March 2001 ) . Schools were r and omised into three groups : group 1 , 238 girls consumed a carton of 330 ml milk fortified with Ca on school days over the study period ; group 2 , 260 girls received the same quantity of milk additionally fortified with 5 or 8 microg cholecalciferol ;  group 3 , 259 control girls .  Anthropometric and bone mineralisation measurements , as well as dietary , health and physical-activity data , were collected at baseline and after 12 and 24 months of the trial . Over the 2-year period the consumption of this milk , with or without added cholecalciferol , led to significant increases in the changes in height ( > or = 0.6 % ) , sitting height ( > or = 0.8 % ) , body weight ( > or 2.9 % ) , and ( size-adjusted ) total-body bone mineral content ( > or = 1.2 % ) and bone mineral density ( > or = 3.2 % ) . Those subjects receiving additional cholecalciferol compared with those receiving the milk without added 25-hydoxycholecalciferol had significantly greater increases in the change in ( size-adjusted ) total-body bone mineral content ( 2.4 v. 1.2 % ) and bone mineral density ( 5.5 v. 3.2 % ) . The milk fortified with cholecalciferol significantly improved vitamin D status at the end of the trial compared with the milk alone or control groups . It is concluded that an increase in milk consumption , e.g. by means of school milk programmes , would improve bone growth during adolescence , particularly when Ca intake and vitamin D status are low BACKGROUND Despite the high prevalence of hypovitaminosis D in children and adolescents worldwide , the impact of vitamin D deficiency on skeletal health is unclear . METHODS One hundred seventy-nine girls , ages 10 - 17 yr , were r and omly assigned to receive weekly oral vitamin D doses of 1,400 IU ( equivalent to 200 IU/d ) or 14,000 IU ( equivalent to 2,000 IU/d ) in a double-blind , placebo-controlled , 1-yr protocol . Areal bone mineral density ( BMD ) and bone mineral content ( BMC ) at the lumbar spine , hip , forearm , total body , and body composition were measured at baseline and 1 yr . Serum calcium , phosphorus , alkaline phosphatase , and vitamin D metabolites were measured during the study . RESULTS In the overall group of girls , lean mass increased significantly in both treatment groups ( P < or = 0.05 ) ; bone area and total hip BMC increased in the high-dose group ( P < 0.02 ) . In premenarcheal girls , lean mass increased significantly in both treatment groups , and there were consistent trends for increments in BMD and /or BMC at several skeletal sites , reaching significance at lumbar spine BMD in the low-dose group and at the trochanter BMC in both treatment groups . There was no significant change in lean mass , BMD , or BMC in postmenarcheal girls . CONCLUSIONS Vitamin D replacement had a positive impact on musculoskeletal parameters in girls , especially during the premenarcheal period Women with low bone density in the radius or calcaneus are at increased risk of  hip fracture . To see whether bone density of the hip measured by dual X-ray absorptiometry is a better predictor of hip fracture than measurements of other bones , we assessed bone density at several sites in 8134 women aged 65 years or more . 65 women had hip fractures during a mean follow-up of 1.8 years . Each SD decrease in femoral neck bone density increased the age-adjusted risk of hip fracture 2.6 times ( 95 % CL 1.9 , 3.6 ) . Women with bone density in the lowest quartile had an 8.5-fold greater risk of hip fracture than those in the highest quartile . Bone density of the femoral neck was a better predictor than measurements of the spine ( p < 0.0001 ) , radius ( p < 0.002 ) , and moderately better than the calcaneus ( p = 0.10 ) . Low hip bone density is a stronger predictor of hip fracture than bone density at other sites . Efforts to prevent hip fractures should focus on women with low hip bone density 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
target: 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 .
background: 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 .