The impact of 1-year vitamin D supplementation on vitamin D status in athletes: a dose–response study Vitamin D Is a Major Determinant of Bone Mineral Density at School Age Vitamin D3 supplementation using an oral spray solution resolves deficiency but has no effect on VO2 max in Gaelic footballers: results from a randomised, double-blind, placebo-controlled trial The effects of season-long vitamin D supplementation on collegiate swimmers and divers. Association between serum 25(OH)D concentrations and bone stress fractures in Finnish young men. Associations of vitamin D status with bone mineral density, bone turnover, bone loss and fracture risk in healthy postmenopausal women. The OFELY study. Vitamin D3 Supplementation Does Not Improve Sprint Performance in Professional Rugby Players: A Randomized, Placebo-Controlled, Double-Blind Intervention Study. A randomized, controlled trial of vitamin D supplementation upon musculoskeletal health in postmenarchal females. Vitamin D status predicts physical performance and its decline in older persons. Vitamin D and attainment of peak bone mass among peripubertal Finnish girls: a 3-y prospective study. A global study of vitamin D status and parathyroid function in postmenopausal women with osteoporosis: baseline data from the multiple outcomes of raloxifene evaluation clinical trial. Vitamin D Supplementation and Physical Performance in Adolescent Swimmers. Vitamin D Supplementation and Fracture Incidence in Elderly Persons Serum 25-Hydroxyvitamin D Concentrations and Risk for Hip Fractures Does vitamin D supplementation of healthy Danish Caucasian girls affect bone turnover and bone mineralization? Effects of Vitamin D Supplementation on Bone Mineral Density and Bone Markers in HIV-Infected Youth The effects of vitamin D3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose–response study
Background / Objectives : To assess the prevalence of vitamin D deficiency in Dutch athletes and to define the required dosage of vitamin D3 supplementation to prevent vitamin D deficiency over the course of a year . Subjects/ Methods : Blood sample s were collected from 128 highly trained athletes to assess total 25(OH)D concentration . Of these 128 athletes , 54 male and 48 female athletes ( 18–32 years ) were included in a r and omized , double blind , dose – response study . Athletes with either a deficient ( < 50 nmol/l ) or an insufficient ( 50–75 nmol/l ) 25(OH)D concentration were r and omly assigned to take 400 , 1100 or 2200 IU vitamin D3 per day orally for 1 year . Athletes who had a total 25(OH)D concentration above 75 nmol/l at baseline continued with the study protocol without receiving vitamin D supplements  . Serum total 25(OH)D concentration was assessed every 3 months , as well as  dietary vitamin D intake and sunlight exposure . Results : Nearly 70 % of all athletes showed an insufficient ( 50–75 nmol/l ) or a deficient ( < 50 nmol/l ) 25(OH)D concentration at baseline . After 12 months , serum 25(OH)D concentration had increased more in the 2200 IU/day group ( + 50±27 nmol/l ) than the sufficient group receiving no supplements ( + 4±17 nmol/l ; P<0.01 ) and the 1100 IU/day group ( + 25±23 nmol/l ; P<0.05 ) . Supplementation with 2200 IU/day vitamin D result ed in a sufficient 25(OH)D concentration in 80 % of the athletes after 12 months . Conclusions : Vitamin D deficiency is highly prevalent in athletes . Athletes with a deficient or an insufficient 25(OH)D concentration can achieve a sufficient 25(OH)D concentration within 3 months by taking 2200 IU/day Background Vitamin D insufficiency in children may have long-term skeletal consequences as vitamin D affects calcium absorption , bone mineralization and bone mass attainment . Methodology /Principal Findings This school-based study investigated vitamin D status and its association with vitamin D intake and bone health in 195 Finnish children and adolescents ( age range 7–19 years ) . Clinical characteristics , physical activity and dietary vitamin D intake were evaluated . Blood and urine sample s were collected for serum 25-hydroxyvitamin D ( 25-OHD ) and other parameters of calcium homeostasis . Bone mineral density ( BMD ) and body composition were measured with dual-energy X-ray absorptiometry ( DXA ) . Altogether 71 % of the subjects were vitamin D insufficient ( 25-OHD < 50 nmol/L ) . The median 25-OHD was 41 nmol/L for girls and 45 nmol/L for boys , and the respective median vitamin D intakes 9.1 µg/day and 10 µg/day . In regression analysis , after adjusting for relevant factors , 25-OHD concentration explained 5.6 % of the variance in lumbar BMD ; 25-OHD and exercise together explained 7.6 % of the variance in total hip BMD and 17 % of the variance in whole body BMD . S-25-OHD was an independent determinant of lumbar spine and whole body BMD and in magnitude surpassed the effects of physical activity . Conclusions / Significance Vitamin D insufficiency was common even when vitamin D intake exceeded the recommended daily intake . Vitamin D status was a key determinant of BMD . The findings suggest urgent need to increase vitamin D intake to optimize bone health in children Purpose Vitamin D inadequacy is a global health concern in athletes as well as the general population . Whilst the role of vitamin D in skeletal health is well defined , there remains uncertainty over whether vitamin D supplementation has an added benefit beyond bone health . Methods This r and omised placebo-controlled trial in healthy male and female Gaelic footballers ( n = 42 ) investigated the effect of vitamin D3 supplementation [ 3000 IU ( 75 µg ) daily for 12 weeks , via an oral spray solution ] on VO2 max which was the primary outcome measure . Secondary outcomes included skeletal muscle and lung function . Results Supplementation significantly increased total 25-hydroxyvitamin D concentrations compared to the placebo group ( mean ± SD change from baseline , 36.31 ± 32.34 vs. 6.11 ± 23.93 nmol/L , respectively ; P = 0.006 ) . At baseline , 50 and 22 % of footballers presented with vitamin D insufficiency ( 31–49 nmol/L ) and deficiency ( < 30 nmol/L ) , respectively . Total 25-hydroxyvitamin D concentration did not significantly correlate with any measure of physical performance . Analysis of covariance ( ANCOVA ) models demonstrated that vitamin D supplementation over 12 weeks had no significant effect on VO2 max ( P = 0.375 ) , vertical jump height ( P = 0.797 ) , left and right h and grip strength ( P = 0.146 and P = 0.266 , respectively ) , forced vital capacity ( P = 0.573 ) or forced expiratory volume at 1 s ( P = 0.665 ) , after adjusting for confounders . The high prevalence of vitamin D inadequacy observed in this cohort of collegiate Gaelic footballers supports the need for vitamin D supplementation during wintertime to avoid being at risk of poor bone health . Conclusions Twelve-week daily supplementation with 3000 IU ( 75 µg ) vitamin D3 successfully resolved deficiency but did not have any significant effect on VO2 max , skeletal muscle or lung function The purpose of this 6-month r and omized , placebo-controlled trial was to determine the effect of season-long ( September-March ) vitamin D supplementation on changes in vitamin D status , which is measured as 25(OH ) D , body composition , inflammation , and frequency of illness and injury . Forty-five male and female athletes were r and omized to 4,000 IU vitamin D ( n = 23 ) or placebo ( n = 22 ) . Bone turnover markers ( NTx and BSAP ) , 25(OH)D , and inflammatory cytokines ( TNF-alpha , IL-6 , and IL1-β ) were measured at baseline , midpoint , and endpoint . Body composition was assessed by DXA and injury and illness data were collected . All athletes had sufficient 25(OH)D ( > 32 ng/ml ) at baseline ( mean : 57 ng/ml ) . At midpoint and endpoint , 13 % and 16 % of the total sample had 25(OH)D < 32 ng/ml , respectively . 25(OH)D was not positively correlated with bone mineral density ( BMD ) in the total body , proximal dual femur , or lumbar spine . In men , total body ( p = .04 ) and trunk ( p = .04 ) mineral-free lean mass ( MFL ) were positively correlated with 25(OH)D. In women , right femoral neck BMD ( p = .02 ) was positively correlated with 25(OH)D. 25(OH)D did not correlate with changes in bone turnover markers or inflammatory cytokines . Illness ( n = 1 ) and injury ( n = 13 ) were not related to 25(OH)D ; however , 77 % of injuries coincided with decreases in 25(OH)D. Our data suggests that 4,000 IU vitamin D supplementation is an inexpensive intervention that effectively increased 25(OH)D , which was positively correlated to bone measures in the proximal dual femur and MFL . Future studies with larger sample sizes and improved supplement compliance are needed to exp and our underst and ing of the effects of vitamin D supplementation in athletes UNLABELLED Low vitamin D level may predict rickets , osteomalacia , or osteoporosis . We examined serum 25(OH)D concentration as a predisposing factor for bone stress fracture in 756 military recruits . The average serum 25(OH)D concentration was significantly lower in the group with fracture , suggesting a relationship between vitamin D and fatigue bone stress fracture . INTRODUCTION Low vitamin D level may predict rickets , osteomalacia , or osteoporosis . Fatigue bone stress fracture is one of the most frequently seen types of overuse injuries in athletes and military recruits . An association was recently shown between vitamin D and BMC . A correlation has also been found between low femoral BMD and stress fractures . We measured serum 25(OH)D concentration in a population sample of military recruits to determine if vitamin D is a predisposing factor for fatigue bone stress fracture . MATERIAL S AND METHODS We prospect ively followed 800 r and omly selected , healthy Finnish military recruits with a mean age of 19 years for developing stress fractures in homogenous circumstances . Blood for serum 25(OH)D concentration was drawn at entry into military service , and the weight , height , body mass index ( BMI ) , muscle strength , and 12-minute running were measured for all subjects . Serum 25(OH)D concentrations were measured with enzyme immunoassay . At end of the 90-day follow-up , 756 subjects completed the study . Subjects without fracture constituted controls . RESULTS Twenty-two recruits with stress fracture were identified ( 2.9 % ) , the incidence being 11.6 ( 95 % CI : 6.8 - 16.5 ) per 100 person-years . In the final multivariate analysis , the significant risk factor for stress fracture in conscripts was a below median serum 25(OH)D level ( 75.8 nM ) , OR being 3.6 ( 95 % CI : 1.2 - 11.1 ) . No significant associations between BMI ( p = 0.255 ) , age ( p = 0.216 ) , or smoking ( p = 0.851 ) and bone stress fracture were found in this study population . CONCLUSIONS A lower level of serum 25(OH)D concentration may be a generally predisposing element for bone stress fractures . Considering the obvious need of additional vitamin D in prevention of stress fractures , the effects of vitamin D fortification of foods and supplementation will be subjects of interest for future research INTRODUCTION Vitamin D status is considered as an important determinant of bone health but supplementation trials with vitamin D(3 ) have yielded conflicting results . The aim of this study was to investigate the associations between serum 25-hydroxyvitamin D ( 25-OH D ) , bone turnover markers , bone mineral density ( BMD ) , radius bone loss and incidence of fracture in postmenopausal women . METHODS 669 postmenopausal women ( mean age : 62.2 years ) belonging to a population -based cohort were followed prospect ively for a median of 11.2 years . At baseline , 25-OH D levels , BMD , bone turnover markers and clinical risk factors of osteoporosis were assessed . BMD loss at the radius was estimated by annual measurements of BMD and all incident fractures which occurred in 134 women were confirmed by radiographs . RESULTS 73 % and 35 % of women had serum 25-OH D levels below 75 and 50 nmol/l which correspond respectively to the median and lowest optimal values recently proposed for fracture prevention . 11 % of women had levels below 30 nmol/l . Serum 25-OH D correlated modestly with intact PTH ( r(2)=0.023 , p<0.0001 ) , but not with bone turnover markers or BMD at the hip and radius after adjustment for age . When levels of 25-OH D were considered as a continuous variable , there was no significant association between 25-OH D levels and radius BMD loss or fracture risk . After adjustment for age , there was no significant difference in incidence of fracture , BMD , radius BMD loss , bone turnover markers , grip strength and the percentage of fallers in the previous year between women with 25-OH D levels below or above 75 , 50 or 30 nmol/l . CONCLUSIONS In a population of home-dwelling healthy postmenopausal women with few of them with severe vitamin D deficiency , vitamin D status may not be an important determinant of bone health Vitamin D insufficiency is common in athletes and may lower physical performance . Many cross-sectional studies associate vitamin D status with physical performance in athletes ; however , there have been few prospect i ve r and omized controlled trials with adequate statistical power to test this relationship , and none in the southern hemisphere . Thus , a prospect i ve double-blind , r and omized , placebo-controlled intervention trial was conducted involving 57 professional rugby union players in New Zeal and . Participants were r and omized to receive 50,000 IU of cholecalciferol ( equivalent to 3,570 IU/day ) or placebo once every two weeks over 11 - 12 weeks . Serum 25(OH)D concentrations and physical performance were measured at baseline , weeks 5 - 6 , and weeks 11 - 12 . Mean ( SD ) serum 25(OH)D concentrations for all participants at baseline was 94 ( 18 ) nmol/L , with all players above 50 nmol/L. Vitamin D supplementation significantly increased serum 25(OH)D concentrations compared to placebo , with a 32 nmol/L difference between groups at 11 - 12 weeks ( 95 % CI , 26 - 38 ; p < 0.001 ) . Performance in five of the six tests at study completion , including the primary outcome variable of 30-m sprint time , did not differ between the vitamin D supplemented and placebo groups ( p > 0.05 ) . Performance on the weighted reverse-grip chin up was significantly higher in players receiving vitamin D compared with placebo , by 5.5 kg ( 95 % CI , 2.0 - 8.9 ; p = 0.002 ) . Despite significantly improving vitamin D status in these professional rugby union players , vitamin D supplementation had little impact on physical performance outcomes . Thus , it is unlikely that vitamin D supplementation is an ergogenic aid in this group of athletes CONTEXT There has been a resurgence of vitamin D deficiency rickets throughout the developed world , with infants and adolescents being primarily affected . Adolescence is a crucial period for muscle and bone mineral accumulation . OBJECTIVE The aim was to determine the effect of vitamin D supplementation on the adolescent musculoskeletal system . DESIGN AND SETTING We conducted a community-based , double-blind , r and omized controlled trial in a secondary school . PARTICIPANTS Postmenarchal 12- to 14-yr-old females participated in the trial . Ninety-nine were screened , 73 were included in r and omized controlled trial , and 69 completed the trial . There were no adverse events . INTERVENTION Four doses of 150,000 IU vitamin D(2 ) ( ergocalciferol ) were given over 1 yr . MAIN OUTCOME MEASURES Dual-energy x-ray absorptiometry , peripheral quantitative computed tomography , and jumping mechanography were used . RESULTS At follow-up , 25-hydroxyvitamin D [ 25(OH)D ] status was 56.0 ± 8.9 nmol/liter in the intervention group and 15.8 ± 6.6 nmol/liter in controls . There were no effects of supplementation on bone ; however , for muscle function , efficiency of movement improved in the vitamin D-treated group . There was an interaction between baseline 25(OH)D concentration and response to vitamin D supplementation for muscle jump velocity . CONCLUSIONS Despite improvements in 25(OH)D status , treatment with vitamin D(2 ) was not shown to increase mineral accretion , bone geometry or strength , muscle force , or power . There were greater increases in jump velocity in girls with the lowest baseline 25(OH)D concentrations . Lack of effect of intervention after the period of peak mineral and muscle mass accretion suggests that earlier action is required CONTEXT Vitamin D deficiency is common among older people and can cause mineralization defects , bone loss , and muscle weakness . OBJECTIVE The aim of this study was to investigate the association of serum 25-hydroxyvitamin D ( 25-OHD ) concentration with current physical performance and its decline over 3 yr among elderly . DESIGN The study consisted of a cross-sectional and longitudinal design ( 3-yr follow-up ) within the Longitudinal Aging Study Amsterdam . SETTING An age- and sex-stratified r and om sample of the Dutch older population was used . OTHER PARTICIPANTS Subjects included 1234 men and women ( aged 65 yr and older ) for cross-sectional analysis and 979 ( 79 % ) persons for longitudinal analysis . MAIN OUTCOME MEASURE(S ) Physical performance ( sum score of the walking test , chair st and s , and t and em st and ) and decline in physical performance were measured . RESULTS Serum 25-OHD was associated with physical performance after adjustment for age , gender , chronic diseases , degree of urbanization , body mass index , and alcohol consumption . Compared with individuals with serum 25-OHD levels above 30 ng/ml , physical performance was poorer in participants with serum 25-OHD less than 10 ng/ml [ regression coefficient ( B ) = -1.69 ; 95 % confidence interval ( CI ) = -2.28 ; -1.10 ] , and with serum 25-OHD of 10 - 20 ng/ml ( B = -0.46 ; 95 % CI = -0.90 ; -0.03 ) . After adjustment for confounding variables , participants with 25-OHD less than 10 ng/ml and 25-OHD between 10 and 20 ng/ml had significantly higher odds ratios ( OR ) for 3-yr decline in physical performance ( OR = 2.21 ; 95 % CI = 1.00 - 4.87 ; and OR = 2.01 ; 95 % CI = 1.06 - 3.81 ) , compared with participants with 25-OHD of at least 30 ng/ml . The results were consistent for each individual performance test . CONCLUSIONS Serum 25-OHD concentrations below 20 ng/ml are associated with poorer physical performance and a greater decline in physical performance in older men and women . Because almost 50 % of the population had serum 25-OHD below 20 ng/ml , public health strategies should be aim ed at this group BACKGROUND Little is known about the effect of vitamin D status on bone gain in adolescents . OBJECTIVE The objective was to examine whether vitamin D status is associated with accrual of bone mineral density ( BMD ) and bone mineral apparent density ( BMAD ) . DESIGN This 3-y prospect i ve study examined the association between changes in BMD or BMAD and serum 25-hydroxyvitamin D [ 25(OH)D ] in 171 healthy Finnish girls aged 9 - 15 y.  Lumbar spine and femoral neck BMDs were measured by dual-energy X-ray absorptiometry . RESULTS Baseline 25(OH)D correlated significantly with the unadjusted 3-y change in BMD at the lumbar spine ( r = 0.35 , P < 0.001 ) and femoral neck ( r = 0.32 , P < 0.001 ) in all participants . The difference from baseline in adjusted 3-y BMD accumulation between those with severe hypovitaminosis D [ 25(OH)D < 20 nmol/L ] and those with a normal vitamin D status [ 25(OH)D > or = 37.5 nmol/L ] was 4 % ( 12.7 % , 13.1 % , and 16.7 % for the lowest , middle , and highest tertiles of 25(OH)D , respectively ; P for trend = 0.01 ) at the lumbar spine in the girls with advanced sexual maturation at baseline ( n = 129 ) . Moreover , the adjusted change in lumbar spine BMD was 27 % greater in the highest vitamin D intake tertile than in the lowest tertile in the same girls ( P for trend = 0.016 ) . CONCLUSIONS Pubertal girls with hypovitaminosis D seem to be at risk of not reaching maximum peak bone mass , particularly at the lumbar spine . Dietary enrichment or supplementation with vitamin D should be considered to ensure an adequate vitamin D status Vitamin D deficiency leads to secondary hyperparathyroidism , increased bone turnover , and bone loss and , when severe , to osteomalacia . Vitamin D deficiency is common in elderly people , especially the institutionalized . The definition of vitamin D deficiency is hampered by the fact that large interlaboratory differences exist in assays for serum 25-hydroxyvitamin D ( 25OHD ) , the main circulating metabolite . The international Multiple Outcomes of Raloxifene Evaluation study , a large prospect i ve intervention trial in postmenopausal women with osteoporosis , offered the opportunity to compare vitamin D status and parathyroid function throughout many countries over the world . For this study , baseline data were available from 7564 postmenopausal women from 25 countries on 5 continents . All women had osteoporosis , i.e. bone mineral density ( BMD ) at femoral neck or lumbar spine was lower than t-score -2.5 , or they had 2 vertebral fractures .  Serum 25OHD was measured by RIA , and  serum PTH  was measured by immunoradiometric assay .  BMD was measured by dual x-ray absorptiometry . The mean ( + /-SD ) serum 25OHD was 70.8 + /- 30.9 nmol/L. A low serum 25OHD ( < 25 nmol/L ) was observed in 4.1 % of all women in the Multiple Outcomes of Raloxifene Evaluation study , ranging from 0 % in south east Asia ( very few patients ) to 8.3 % in southern Europe . Serum 25OHD was between 25 - 50 nmol/L in 24.3 % of the women . Serum 25OHD showed a significant seasonal relationship , with lower values in all regions in winter . Serum PTH correlated negatively with serum 25OHD ( r = -0.25 ; P < 0.001 ) . This significant negative correlation was observed in all regions . When serum 25OHD was less than 25 , 25 - 50 , or more than 50 nmol/L , respectively , mean serum PTH levels were 4.8 , 4.1 , and 3.5 pmol/L , respectively ( by ANOVA , P < 0.001 ) . Similarly , mean alkaline phosphatase levels were 83.7 , 79.1 , and 75.7 U/L ( P < 0.001 ) , respectively , with increasing serum 25OHD . The effect of serum 25OHD on BMD was only significant for the BMD of the trochanter where a serum 25OHD level less than 25 nmol/L was associated with a 4 % lower BMD . After 6 months of treatment with vitamin D(3 ) ( 400 - 600 IU/day ) and calcium ( 500 mg/day ) , serum 25OHD increased from 70.8 + /- 29.8 to 92.3 + /- 28.6 nmol/L. Serum PTH decreased significantly after 6 months of treatment , and this decrease depended on baseline serum 25OHD . When baseline serum 25OHD was less than 25 , 25 - 50 , or more than 50 nmol/L , respectively , serum PTH decreased by 0.8 , 0.5 , or 0.2 pmol/L , respectively ( P < 0.001 ) . In conclusion , serum 25OHD was less than 25 nmol/L in 4 % of the women , and this was associated with a 30 % higher serum PTH . In 24 % of the women  serum 25OHD was between 25 - 50 nmol/L , associated with a 15 % higher level of serum PTH compared with women with a serum 25OHD greater than 50 nmol/L. A low serum 25OHD level was also associated with higher serum alkaline phosphatase and lower BMD of the trochanter . Treatment with vitamin D(3 ) and calcium increased serum 25OHD and decreased serum PTH significantly ; the effect was greater for lower baseline serum 25OHD It is hypothesized that vitamin D insufficiency in athletes might negatively affect sport performance . The objective of this study was to examine the effect of vitamin D3 supplementation on physical performance of adolescent swimmers with vitamin D insufficiency . Fifty-three adolescent competitive swimmers with vitamin D insufficiency ( serum 25-hydroxyvitamin-D concentrations ( 25(OH)D ) < 30 ng/ml , mean 24.2 ± 4.8 ng/ml ) were r and omized to receive 2,000 IU/day of vitamin D3 or placebo for 12 weeks . Swimming performance at several speeds , arm-grip strength , and one-legged balance , were measured before and after supplementation . The age-adjusted changes in performance variables during the study were compared between groups . 25(OH ) D concentrations at study end were significantly higher in the vitamin group compared with the placebo group ( 29.6 ± 6.5 ng/ml vs. 20.3 ± 4.2 ng/ml , p < .001 ) , yet only 48 % of the vitamin group became vitamin D sufficient with this dosing . No between-group differences were found in the changes of the performance variables tested . No significant differences in performance were found between participants that became vitamin D sufficient , and those who did not . No significant correlation was found between the change in serum 25(OH)D and age-adjusted balance , strength or swimming performance at study end . Vitamin D3 supplementation that raised serum 25(OH)D concentrations by a mean of 9.3 ng/ml above placebo in adolescent swimmers with vitamin D insufficiency , did not improve physical performance more than placebo Vitamin D deficiency is common in elderly persons , especially those with hip fracture [ 1 , 2 ] . It is caused by low exposure to sunshine , decreased synthesis of vitamin D3 in the aging skin , and a diet low in vitamin D [ 3 , 4 ] . The mean vitamin D intake in elderly persons in the Netherl and s is about 100 IU/d , half that of elderly persons in the United States [ 5 ] . Most of this vitamin D comes from margarine , which is the only vitamin D-supplemented food in the Netherl and s ( 3 IU/g ) . In vitamin D deficiency , the low serum concentration of 25-hydroxyvitamin D [ 25(OH)D ] leads to a low 1,25-dihydroxyvitamin D [ 1,25(OH)2D ] concentration and then to a higher serum parathyroid hormone concentration , especially in the winter [ 6 - 10 ] . Histologically , the increased parathyroid activity is associated with high bone turnover , leading to cortical bone loss and low density bone [ 5 , 11 ] , which may lead to hip fracture . We previously studied the effects of vitamin D supplementation in residents of a home for the elderly and residents of a nursing home [ 10 ] .  Vitamin D3 , 400 IU/d , led to an adequate increase of the serum 25(OH)D concentration , to a small but significant increase of the serum 1,25(OH)2D concentration , and to a decrease of the serum concentration of intact parathyroid hormone . It was recently observed [ 12 , 13 ] that bone mineral density at the hip is positively related to serum 25(OH)D concentration in postmenopausal and elderly women . Therefore , it might be expected that vitamin D supplementation would increase bone mineral density in elderly persons deficient in vitamin D. In line with this expectation , it was shown that vitamin D supplementation prevented bone loss from the spine during the winter in postmenopausal women [ 14 ] . These results suggest that vitamin D supplementation may reduce the incidence of hip fractures , because bone strength shows a strong correlation with bone mineral density [ 15 ] . However , increasing bone mineral density through a therapeutic intervention does not necessarily lead to increased bone strength , as has been shown with sodium fluoride [ 16 ] . Bone structure and bone quality are also determinants of bone strength [ 17 ] , and falls are a risk factor for hip fractures [ 18 ] . Therefore , hip fracture should be the outcome criterion in studies on the effect of vitamin D supplementation . Intervention studies on the prevention of osteoporotic fractures necessitate large numbers of patients , because the outcome has an annual incidence of 0.5 % to 4 % in the elderly population [ 19 ] . We report the results of a large-scale , prospect i ve study on the effect of vitamin D supplementation on the incidence of hip and other osteoporotic fractures . Methods Participants The study included 2578 persons ( 1916 women and 662 men ) 70 years of age and older ( mean age SD , 80 6 years ; range , 70 to 97 years ) . Participants were recruited from general practitioners , from apartment houses for elderly persons , and from homes for elderly persons in Amsterdam and its vicinity . Persons recruited from practitioners were living independently ; those recruited from apartment houses and homes were receiving some care , but less than they would have received in a nursing home . Participants had to be reasonably healthy and able to give informed consent . Persons with a history of hip fracture or total hip arthroplasty , known hypercalcemia , sarcoidosis , or recent urolithiasis ( < 5 years earlier ) were excluded . Patients who had diseases or who used medications that influence bone metabolism ( such as thyroid disease or glucocorticoid medication ) were not excluded . The spontaneous use of vitamin D supplements and multivitamins was discouraged , but the prescription practice s of the general practitioners were not altered . All vitamin use was carefully documented . The study was approved by the Ethical Review Board of the Vrije Universiteit Hospital , and all participants gave informed consent . Study Design After checking the inclusion and exclusion criteria and obtaining informed consent , the participants were r and omly assigned to receive either active treatment with vitamin D3 or placebo . The study was double-blind , and r and omization was done in blocks of 10 per general practice , apartment house , or home . R and omization lists were made using a computerized r and om-number generator . Lists in sealed envelopes were sent to the hospital pharmacy for assignment . Each participant took either one tablet per day that contained vitamin D3 , 400 IU , or one placebo tablet per day that was identical in appearance and taste to the vitamin tablet . After enrollment , the participants received the first container of tablets ( 210 tablets ) . The container was replaced every 6 months with a full container . All participants were also advised in writing to consume at least three servings of dairy products per day ( for example , 1 glass of milk , 1 cup of yogurt , and 1 slice of cheese ) to ensure a calcium intake of at least 800 to 1000 mg/d . The study was started in August 1988 . The last participant was enrolled in December 1990 , and all participants had stopped using study medication by December 1993 . The follow-up period had been planned to last no more than 3 years , but because the number of hip fractures during the study was lower than expected , a 6-month extension was planned . The study participants thus received medication for 3 to 3.5 years ; those who received it for 3.5 years were those who consented to the 6-month extension . Total follow-up was to a maximum of 4 years . Data collected at baseline included an  outdoor activity score  ( 1 equals going outdoors less than once a week ; 2 equals going outdoors 1 or 2 times per week ; and 3 equals going outdoors 3 times per week or more ) and a score for sunshine exposure ( when outside : 1 equals in the shade as much as possible ; 2 equals sometimes in sunshine ; 3 equals much exposure to sunshine ) . These scores show a positive relation with serum 25(OH)D concentration [ 3 ] . Mobility was estimated by a walking score that ranged from 1 ( unable to walk ) to 5 ( walks independently a fair distance on any surface ) [ 20 ] . The dietary calcium intake from dairy products was estimated in a subset of 348 women by using a question naire , as described previously [ 21 ] . The participants were evaluated annually with a question naire on hip fractures , other peripheral fractures , outdoor score , sunshine exposure score , use of vitamin supplements , and walking score . Each general practitioner or caretaker was asked to immediately report change of address , hip fracture , or death . Hip fracture and death were verified by the general practitioner . All participants were followed for the maximal period of 4 years if possible , even if they had stopped using the trial medication , had sustained a fracture , or had moved to another city . To investigate possible selection bias , 267 potential participants in a home for the elderly and its adjunct apartments ( all residents of the institution ) were studied for baseline characteristics , including age , sex , sunshine exposure score , outdoor score , walking score , and reasons for nonparticipation . Compliance was checked when the tablet containers were replaced ( every 6 months ) , by question naire ( every year ) , and by measurement of the serum 25(OH)D concentration . Serum 25(OH)D concentration was measured at baseline and after 1 year in 270 persons who participated in a sub study investigating the effect of vitamin D supplementation on bone mineral density and bone turnover variables . This sub study included a nonr and om sample of participants from several apartment houses and homes for the elderly and is described in detail elsewhere [ 21 ] . In the same sub study , dietary calcium intake from diary products was assessed . Serum 25(OH)D concentration was also estimated during the third year of the study in February and March in a r and om sample of 96 participants drawn from the remaining study population . These participants received a letter giving them an appointment within 10 days ; the blood sample s were drawn at home . Serum 25(OH)D concentration was measured by competitive protein binding assay after being purified by gradient high-pressure liquid chromatography . The intra- and interassay coefficients of variation were 5 % and 6 % , respectively [ 22 ] . Statistical Analysis Baseline data of the vitamin D group and the placebo group were compared using t-tests ( age , calcium intake ) , chi-square tests ( sex , residence ) , and Wilcoxon rank-sum tests ( scores ) . The serum 25(OH)D concentrations of both groups were compared using t-tests . Data on fractures and mortality were analyzed by survival analysis using log-rank tests , Cox proportional-hazards regression , and hazard rate ratios [ 23 ] . Hip fractures are presented using the Kaplan-Meier method . All participants were kept in the study as long as possible . The data were analyzed in two ways . The intention-to-treat analysis included all r and omly assigned participants for either the total follow-up period or until fracture , death , or loss to follow-up . The active treatment analysis included the participants as long as they stated that they were using the trial medication . Thus , the participants were included in the active treatment analysis until they stopped using the trial medication , regardless of whether a fracture occurred after they had stopped . Age , sex , and residence were added in both analyses as covariates to the Cox regression model . Because outdoor score , sunshine score , and walking score were interrelated ( correlation coefficients ranging from 0.21 to 0.59 ) and were likely to indicate general health or mobility , they were averaged over the years and added up to a sum score . For this purpose , the walking score was simplified ( 1 , 2 , or 3 equals 1 ; 4 equals 2 ; 5 equals 3 ) , because the lower walking scores applied to a few participants only . The result ing total score , ranging from 3 to 9 , was entered as a covariate in the model . The level of compliance ( weekly intake as reported on Context Vitamin D supplementation may help prevent fractures , but the relationship between blood vitamin D concentrations and fracture risk is unclear . Contribution These authors observed an increased risk for hip fracture among women with lower serum 25-hydroxyvitamin D [ 25(OH ) vitamin D ] concentrations that was independent of measures of frailty , body mass index , physical function , and falls . Caution The authors did not measure bone mineral density ( BMD ) , so they could not determine whether 25(OH ) vitamin D concentrations give different information about fracture risk than that offered by BMD . Implication Low serum 25(OH ) vitamin D concentrations seem to be associated with a higher hip fracture risk . The Editors Vitamin  D deficiency is common in older adults , especially during the winter ( 1 ) and in homebound population s ( 2 ) , general medical in patients ( 3 ) , and community-dwelling women admitted to the hospital with acute hip fracture ( 4 ) . A recently published evidence -based report on vitamin D and bone health ( 5 ) found the level of evidence for an association between serum 25-hydroxyvitamin D [ 25(OH ) vitamin D ] concentrations and fracture risk to be inconsistent ( 5 ) . Since publication of that review , 1 prospect i ve study ( 6 ) reported no relationship between serum 25(OH ) vitamin D concentrations and fractures , whereas another ( 7 ) reported a significantly lower risk for hip fracture with 25(OH ) vitamin D concentrations greater than 60 nmol/L. Vitamin D concentration could be associated with fractures in several ways . It could influence muscle strength and balance , both of which contribute to falls and disability ( 810 ) . The association between 25(OH ) vitamin D concentrations and fracture may also be influenced by renal function , because renal insufficiency has been linked to fracture ( 11 ) and to vitamin D deficiency ( 12 ) . Several interactions between vitamin D and estrogen receptors have been described ( 13 ) ; hormone therapy has been shown to reverse abnormalities in vitamin D metabolism ( 14 ) , and low vitamin D concentrations have also been linked to higher bone turnover ( 15 , 16 ) . Thus , sex-steroid hormones and bone turnover could contribute to the association between 25(OH ) vitamin D concentration and fractures . We conducted a nested casecontrol study within the WHI-OS ( Women 's Health Initiative Observational Study ) among 400 case- patients with adjudicated incident hip fracture and 400 control participants . We tested whether low serum 25(OH ) vitamin D concentrations are associated with a higher risk for hip fractures in community-dwelling women and whether this relationship may be mediated by poor physical functioning , frailty , falls , sex-steroid hormones , renal function , or bone turnover . Methods Study Population Our study population came from the WHI-OS , a prospect i ve cohort study that enrolled 93676 women between 1994 and 1998 at 40 U.S. clinical centers ( age range , 50 to 79 years ) . Study methods are described in detail elsewhere ( 17 ) . In brief , women were eligible if they were postmenopausal , were unlikely to move or die within 3 years , were not enrolled in the WHI clinical trials , and were not currently participating in any other clinical trial . The human subjects review committees from each participating institution approved the study . Follow-up and Outcome Ascertainment We sent women question naires annually to report any hospitalization and other outcomes , including fractures . As of August 2004 , median follow-up duration was 7.1 years ( range , 0.7 to 9.3 years ) . At that time , 3.7 % of participants had withdrawn or were lost to follow-up and 5.3 % had died . We review ed medical records to verify cases of hip fracture , and blinded central adjudicators confirmed the cases ( 18 ) . We excluded patients with pathologic hip fractures . Nested CaseControl Study Design The present study is a casecontrol study nested within the prospect i ve design of WHI-OS . We excluded women who had a history of hip fracture ; were receiving hormone therapy up to 1 year before enrollment ; or were currently receiving and rogens , selective estrogen receptor modulators , antiestrogens , or other osteoporosis treatments ( bisphosphonates , calcitonin , or parathyroid hormone ) . We also excluded women with insufficient serum stored or of unknown ethnicity , leaving 39793 eligible participants . Of these , 404 women had a hip fracture . We r and omly selected 400 of these women to form the incident hip fracture group . For each case-patient , we selected 1 control participant who was within 1 year of the case-patient 's age at screening , was of matching race or ethnicity , and had their blood drawn within 120 days of the case-patient 's blood draw date ; 99 % of case- patients and control participants were matched within 30 days . Baseline Clinical Variables We divided clinical centers into 3 geographic regions on the basis of latitude : northern ( > 40 N ) , middle ( 35 to 40 N ) , and southern ( < 35 N ) . We ascertained all covariates at baseline . Clinic interviewers recorded current use of prescription medications by direct inspection of medicine containers . We entered prescription names into the WHI data base and assigned drug codes by using Medispan software ( First Data Bank , San Bruno , California ) . Average amounts of elemental calcium and vitamin D preparations were entered directly from supplement containers . Dietary intakes of calcium and vitamin D were assessed by using a semiquantitative food-frequency question naire ( 19 ) . Total calcium and vitamin D intake was defined as the sum of diet and supplements . We used question naires to ascertain date of birth , race or ethnicity , age at menopause , history of any fracture after age 55 years , smoking , parental history of hip fracture , self-rated health status , and alcohol consumption . We classfied physical activity on the basis of frequency and duration of walking and mild , moderate , and strenuous activities in the previous week . We calculated kilocalories of energy expended in 1 week as the metabolic equivalent ( kcal hours/week per kg ) ( 20 ) . We measured physical function by using the R AND Short Form-36 physical function scale , which comprises 10 items measuring whether health now limits physical function in moderate or vigorous activity ( 2 items ) ; strength to lift , carry , stoop , bend , or stair climb ( 4 items ) ; ability to walk various distances without difficulty ( 3 items ) ; and self-care ( 1 item ) ( 21 ) . The scale is scored from 0 to 100 , with higher scores indicating better physical function . We compared women with a score greater than 90 versus those with a score less than or equal to 90 , a cutoff value corresponding to the median score . We computed a frailty score , which included self-reported muscle weakness and impaired walking speed ( R AND Short Form-36 physical function scale score < 75 ) , exhaustion ( R AND Short Form-36 vitality scale score < 55 ) , low physical activity ( lowest quartile of physical activity ) , and unintended weight loss between baseline and 3 years of follow-up ( 22 ) . A woman was considered frail if she reported 3 or more of these indicators . Weight was measured on a balance-beam scale with the participant dressed in indoor clothing without shoes . Height was measured by using a wall-mounted stadiometer . Body mass index was calculated as weight ( in kg ) divided by height ( in m2 ) . Laboratory Procedures Laboratory personnel blinded to casecontrol status obtained a 12-hour fasting blood sample at the baseline visit , which was processed and stored at 80C according to strict quality control procedures ( 23 ) . Serum 25(OH ) vitamin D concentrations and sex-steroid hormone levels were measured at the Reproductive Endocrine Research Laboratory at the University of Southern California .  25-Hydroxyvitamin vitamin D was measured by using a radioimmunoassay with DiaSorin reagents ( DiaSorin , Stillwater , Minnesota ) . The sensitivity of the assay was 3.75 nmol/L. The interassay coefficients of variation were 11.7 % , 10.5 % , 8.6 % , and 12.5 % at 14.0 , 56.8 , 82.5 , and 122.5 nmol/L , respectively . Estradiol and testosterone concentrations were quantified by using sensitive and specific radioimmunoassays after organic solvent extraction and celite column partition chromatography ( 2427 ) . The intra- and interassay coefficients of variation were 7.9 % and 8 % to 12 % , respectively , for estradiol and 6 % and 10 % to 12 % , respectively , for testosterone . We calculated bioavailable hormone concentrations by using mass action equations ( 2830 ) . We measured sex hormonebinding globulin by using a solid-phase , 2-site chemiluminescent immunoassay . The intra- and interassay coefficients of variation were 4.1 % to 7.7 % and 5.8 % to 13 % , respectively . Serum cystatin C , a marker of renal function that is independent of age and weight , was measured at Medical Research Laboratories International , Highl and Heights , Kentucky , by using the Dade Behring BN-II nephelometer and Dade Behring reagents ( Dade Behring , Ramsey , Minnesota ) in a particle-enhanced immunonepholometric assay . Serum C-terminal telopeptide of type I collagen and aminoterminal procollagen extensions propeptide were measured by immunoassay ( Synarc , Lyon , France ) . Statistical Analysis We used chi-square and t tests to compare baseline characteristics between case- patients with hip fracture and matched control participants . We assigned 25(OH ) vitamin D concentrations to quartile categories defined on the basis of the distribution in the control participants . To further assess confounding , we compared baseline characteristics across quartiles of 25(OH ) vitamin D concentrations in case- patients and control participants combined . We calculated the P values for trend by using logistic regression and coding the variable of interest as a continuous variable . We assessed the association between serum 25(OH ) vitamin D concentrations and incident hip fracture in conditional logistic regression models that retained the matched casecontrol design . We first examined the unadjusted associations and then adjusted for age , INTRODUCTION A high peak bone mass may be essential for reducing the risk of osteoporosis later in life and a sufficient vitamin D level during puberty may be necessary for optimal bone accretion and obtaining a high peak bone mass . Dietary intake and synthesis during winter of vitamin D might be limited but the effect of vitamin D supplementation in adolescence on bone mass is not well established . OBJECTIVE To investigate the effect of supplementation with 5 and 10 microg/day vitamin D(3 ) for 12 months in 11- to 12-year-old girls on  bone mass and bone turnover as well as the possible influence of VDR and ER genotype on the effect of the supplementation . METHODS The girls ( n=221 ) were r and omized to receive either 5 microg or 10 microg vitamin D(3 ) supplementation per day or placebo for 12 months . Whole body and lumbar spine bone mass measured by DXA and pubertal status were determined at baseline and after 12 months whereas physical activity and dietary intake of calcium and vitamin D were assessed at baseline . Serum ( S ) 25-hydroxyvitamin D ( 25OHD ) , S-osteocalcin , S-parathyroid hormone , S-calcium , S-inorganic phosphate , urinary ( U ) pyridinoline ( Pyr ) and deoxpyridinoline ( Dpyr ) were measured at baseline and after 6 and 12 months . RESULTS The S-25OHD concentration increased ( p<0.001 ) relative to the baseline values in the groups receiving either 5 microg/day ( mean+/-SD ; 11.0+/-10.3 nmol/l , baseline 41.9+/-17.6 nmol/l ) or 10 microg/day ( 13.3+/-11.8 nmol/l , baseline 44.4+/-16.6 nmol/l ) vitamin D(3 ) for 12 months compared to placebo ( -3.1+/-9.8 nmol/l , baseline 43.4+/-17.1 nmol/l ) . There was no effect of vitamin D-supplementation on biomarkers for bone turnover or on whole body or spine bone mineral augmentation . However , vitamin D supplementation increased whole body bone mineral density ( BMD ) ( p=0.007 ) and bone mineral content ( BMC ) ( p=0.048 ) in the FF VDR genotype but not in the Ff or ff VDR genotypes . CONCLUSION Supplementation with vitamin D ( 5 or 10 microg/day ) over 12 months increased the S-25OHD concentration but there was no effect on indices of bone health in the entire group of girls . However , there was an effect on BMD for a subgroup with the FF VDR genotype indicating an influence of genotype Background : Low bone mineral density ( BMD ) is a significant comorbidity in HIV . However , studies evaluating vitamin D supplementation on bone health in this population are limited . This study investigates changes in bone health parameters after 12 months of supplementation in HIV-infected youth with vitamin D insufficiency . Methods : This is a r and omized , active-control , double-blind trial investigating changes in bone parameters with 3 different vitamin D3 doses [ 18,000 ( st and ard/control dose ) , 60,000 ( moderate dose ) , and 120,000 IU/monthly ( high dose ) ] in HIV-infected youth 8–25 years old with baseline serum 25-hydroxyvitamin D ( 25(OH)D ) concentrations < 30 ng/mL.  BMD and bone turnover markers were measured at baseline and 12 months . Results : One hundred two subjects enrolled . Over 12 months , serum 25(OH)D concentrations increased with all doses , but the high dose ( ie , 120,000 IU/monthly ) maintained serum 25(OH)D concentrations in an optimal range ( ≥30 or ≥20 ng/mL ) throughout the study period for more subjects ( 85 % and 93 % , respectively ) compared with either the moderate ( 54 % and 88 % , respectively ) or st and ard dose ( 63 % and 80 % , respectively ) . All dosing groups showed some improvement in BMD ; however , only the high-dose arm showed significant decreases in bone turnover markers for both procollagen type 1 aminoterminal propeptide ( −3.7 ng/mL ; P = 0.001 ) and & Bgr;-CrossLaps ( −0.13 ng/mL ; P = 0.0005 ) . Conclusions : High-dose vitamin D supplementation ( 120,000 IU/mo ) given over 12 months decreases bone turnover markers in HIV-infected youth with vitamin D insufficiency , which may represent an early , beneficial effect on bone health . High vitamin D doses are needed to maintain optimal serum 25(OH)D concentrations Background Vitamin D deficiency is common in the general public and athletic population s and may impair skeletal muscle function . We therefore assessed the effects of vitamin D3 supplementation on serum 25[OH]D concentrations and physical performance . Methods 30 club-level athletes were block r and omised ( using baseline 25[OH]D concentrations ) into one of three groups receiving either a placebo ( PLB ) , 20 000 or 40 000 IU/week oral vitamin D3 for 12 weeks . Serum 25[OH]D and muscle function ( 1-RM bench press and leg press and vertical jump height ) were measured presupplementation , 6 and 12 weeks postsupplementation . Vitamin D deficiency was defined in accordance with the US Institute of Medicine guideline ( < 50 nmol/l ) . Results 57 % of the subject population were vitamin D deficient at baseline ( mean±SD value 51±24 nmol/l ) . Following 6 and 12 weeks supplementation with 20 000 IU ( 79±14 and 85±10 nmol/l , respectively ) or 40 000 IU vitamin D3 ( 98±14 and 91±24 nmol/l , respectively ) , serum vitamin D concentrations increased in all participants , with every individual achieving concentrations greater than 50 nmol/l . In contrast , vitamin D concentration in the PLB group decreased at 6 and 12 weeks ( 37±18 and 41±22 nmol/l , respectively ) . Increasing serum 25[OH]D had no significant effect on any physical performance parameter ( p>0.05 ) . Conclusions Both 20 000 and 40 000 IU vitamin D3 supplementation over a 6-week period elevates serum 25[OH]D concentrations above 50 nmol/l , but neither dose given for 12 weeks improved our chosen measures of physical performance
Conclusion Despite the limitations of the current evidence , the prevalence of vitamin D inadequacy in athletes is prominent .
The risk significantly increases in higher latitudes , in winter and early spring seasons , and for indoor sport activities .
The prevalence of injuries in athletes is notable but its association with  vitamin D status is unclear .
Background Vitamin D is essential for maintaining optimal bone health .
The prevalence of vitamin D inadequacy in athletes is currently unclear .
Objective The objective of this study is to determine the prevalence of vitamin D inadequacy in athletes .
Serum 25(OH)D is measured to clinical ly determine vitamin D status .