Vitamin D Supplementation and Physical Performance in Adolescent Swimmers. Effect of vitamin D supplementation on inflammation: protocol for a systematic review The effects of vitamin D3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose–response study Correcting Vitamin D Insufficiency Improves Some But Not All Aspects of Physical Performance During Winter Training in Taekwondo Athletes. Vitamin D3 Supplementation Does Not Improve Sprint Performance in Professional Rugby Players: A Randomized, Placebo-Controlled, Double-Blind Intervention Study. Efficacy of vitamin D supplementation in depression in adults: a systematic review protocol The impact of 1-year vitamin D supplementation on vitamin D status in athletes: a dose–response study The influence of winter vitamin D supplementation on muscle function and injury occurrence in elite ballet dancers: a controlled study. A systematic review protocol examining the effect of vitamin D supplementation on endothelial function Serum 25-Hydroxyvitamin D Concentrations and Risk for Hip Fractures Calcium Absorption Varies within the Reference Range for Serum 25-Hydroxyvitamin D Vitamin A to prevent bronchopulmonary dysplasia in very-low-birth-weight infants: has the dose been too low? The NICHD Neonatal Research Network. Acute Effects of Vitamin D3 Supplementation on Muscle Strength in Judoka Athletes: A Randomized Placebo-Controlled, Double-Blind Trial Vitamin D: do we get enough? Serum Vitamin D levels and Vitamin D supplementation do not correlate with the severity of chronic eczema in children. Association Between Vitamin D Supplementation During Pregnancy and Offspring Growth, Morbidity, and Mortality Vitamin D intake is low and hypovitaminosis D common in healthy 9− to 15-year-old Finnish girls 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 Effect of Bimonthly Supplementation With Oral Cholecalciferol on Serum 25-Hydroxyvitamin D Concentrations in HIV-Infected Children and Adolescents Efficacy of daily and monthly high-dose calciferol in vitamin D-deficient nulliparous and lactating women. Cholecalciferol supplementation does not influence β-cell function and insulin action in obese adolescents: a prospective double-blind randomized trial. Are Hill's criteria for causality satisfied for vitamin D and periodontal disease? Vitamin D supplementation in the prevention and management of major chronic diseases not related to mineral homeostasis in adults: research for evidence and a scientific statement from the European society for clinical and economic aspects of osteoporosis and osteoarthritis (ESCEO)
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 Introduction The extraskeletal role of vitamin D is being increasingly recognised . This has important clinical implication s , as vitamin D deficiency has reached epidemic proportions worldwide . Vitamin D has proposed anti-inflammatory properties , yet the role of vitamin D supplementation in reducing inflammation remains largely unknown . The purpose of this review is to investigate the impact of vitamin D supplementation on inflammation , and to identify relevant knowledge gaps in the field . Methods and analysis Medline , CINAHL , EMBASE and All EBM will be systematic ally search ed for r and omised controlled trials ( RCTs ) and systematic review s of RCTs , comparing vitamin D supplementation with placebo , usual care or other pharmacological or non-pharmacological interventions . One review er will assess articles for eligibility according to prespecified selection criteria , after which 2 independent review ers will perform data extraction and quality appraisal . Meta-analyses will be conducted where appropriate . Ethics and dissemination Formal ethical approval is not required as no primary data is collected . This systematic review will identify potential clinical implication s of vitamin D deficiency and supplementation , and will be disseminated through a peer- review ed publication and at conference meetings , to inform future research on the efficacy of vitamin D supplementation for inflammation and inflammatory diseases . PROSPERO registration number CRD42016037104 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 We investigated the effects of vitamin D3 supplementation on physical performance during winter training in vitamin D insufficient taekwondo athletes . Thirty-five collegiate male and female taekwondo athletes , aged 19 - 22 years with low serum 25(OH)D concentration ( 28.8 ± 1.10 nmol/L ) , were r and omly assigned to a vitamin D group ( n = 20 ) or a placebo group ( n = 15 ) . Subjects received either a vitamin D3 capsule ( 5,000 IU/day ) or a placebo during 4 weeks of winter training . Blood sample s were collected for analyzing serum 25(OH)D concentration . Physical performance tests included Wingate anaerobic test , isokinetic muscle strength and endurance , a countermovement jump test , sit-ups , agility test , and 20-m pacer . Serum 25(OH)D concentrations increased significantly in the vitamin D group ( 96.0 ± 3.77 nmol/L ) after 4 weeks of supplementation , but no changes were found in the placebo group ( F = 242.44 , p = .000 ) . There were significant interaction effects for anaerobic peak power ( F = 7.49 , p = .010 ) and isokinetic knee extension at 180 deg/s ( F = 6.08 , p = .019 ) . Changes in serum 25(OH)D concentration were positively associated with changes in peak power and isokinetic knee extension at 180 deg/s . However , no significant interaction effects were observed in other performance variables . This study suggests that 4 weeks of vitamin D supplementation elevates serum 25(OH)D concentration to sufficient levels . Correcting vitamin D insufficiency improves some but not all aspects of performance . Thus , efficacy of vitamin D supplementation to enhance performance remains unclear 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 Background The role of vitamin D in management of depression is unclear . Results from observational and emerging r and omized controlled trials ( RCTs ) investigating the efficacy of vitamin D in depression lack consistency - with some suggesting a positive association while others show a negative or inconclusive association . Methods / Design The primary aim of this study is to conduct a systematic review of RCTs to assess the effect of oral vitamin D supplementation versus placebo on depression symptoms measured by scales and the proportion of patients with symptomatic improvement according to the authors ’ original definition . Secondary aims include assessing the change in quality of life , adverse events and treatment discontinuation . We will conduct the systematic review and meta- analysis according to the recommendations of the Cochrane H and book for Systematic Review s of Interventions . We will search the Cochrane Central Register of Controlled Trials ( CENTRAL ) , MEDLINE ( 1966 to present ) , EMBASE ( 1980 to present ) , CINAHL ( 1982 to present ) , PsychINFO ( 1967 to present ) and Clinical Trials.gov . Unpublished work will be identified by search ing two major conferences : the International Vitamin Conference , the Anxiety Disorders and Depression Conference , while grey literature will be acquired by contacting authors of included studies . We will use the r and om-effects meta- analysis to synthesize the data by pooling the results of included studies . Discussion The results of this systematic review will be helpful in clarifying the efficacy of vitamin D supplementation and providing evidence to establish guidelines for implementation of vitamin D for depression in general practice and other relevant setting s. Study registration Unique identifier : CRD42013003849 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 OBJECTIVES Athletes who train indoors during the winter months exhibit low serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations due to a lack of sunlight exposure . This has been linked to impaired exercise performance . The purpose of this study was to assess the effects of oral vitamin D₃ supplementation on selected physical fitness and injury parameters in elite ballet dancers . DESIGN Controlled prospect i ve study . METHODS 24 elite classical ballet dancers ( intervention n=17 ; control n=7 ) participated in a controlled 4-month oral supplementation of vitamin D₃ ( 2000 IU per day ) . Isometric muscular strength and vertical jump height were measured pre and post intervention . Injury occurrence during the intervention period was also recorded by the in-house medical team . Repeated measures ANOVA and Mann-Whitney-U statistical tests were used and significance was set at p ≤ 0.05 . RESULTS Significant increases were noted for the intervention group for isometric strength ( 18.7 % , p<0.01 ) and vertical jump ( 7.1 % , p<0.01 ) . The intervention group also sustained significantly less injuries than the controls during the study period ( p<0.01 ) . CONCLUSIONS Oral supplementation of vitamin D₃ during the winter months has beneficial effects on muscular performance and injury occurrence in elite ballet dancers Introduction Vitamin D has potential benefits for extraskeletal health . These could include an anti-inflammatory effect as well as a reduction in endothelial dysfunction . We aim to provide quality evidence for the hypothesis that supplementation with vitamin D will improve endothelial function ( EF ) , possibly through the abrogation of systemic inflammation . Methods and analysis We will conduct a systematic review of all r and omised controlled trials on  vitamin D supplementation and EF lasting 12 weeks or more . The search will cover the period 2000–2015 and include studies that describe direct measures of EF  , markers of endothelial cell ( EC ) activation  and if concurrently reported , indicators of systemic inflammation  . Study selection will follow the Preferred Reporting Items for Systematic Review s and Meta-Analyses ( PRISMA ) guidelines and study quality will be assessed by the Jadad score in addition to an evaluation of allocation concealment and data analysis . If sufficient data are available , a meta- analysis will be conducted . The effect sizes will be generated using Hedges ’ g score , for both fixed and r and om effect models . I2 statistics and Galbraith plots will be used to assess heterogeneity and identify their potential sources . Potential publication and small sample size bias will be assessed by visual inspections of funnel plots and also Egger 's test . Meta-regression analysis ( if feasible ) will be conducted with restricted maximum likelihood ( REML ) estimation method , controlling for potential confounders ( demographics , study methods , location , etc ) . A backward elimination process will be applied in the regression modelling procedure . Subgroup analysis , conditional on number of studies retrieved and their sample size , will be stratified on participant disease category , total dose administered , degree of 25(OH)D change and type of supplement used . Ethics and dissemination Formal ethical approval is not required as primary data will not be collected . The results will be disseminated through a peer- review ed publication , conference presentation and the popular press . Trial registration number International Prospect i ve Register for Systematic Review s ( PROSPERO ) number CRD42014013523 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 , Background : Calcium absorption is generally considered to be impaired under conditions of vitamin D deficiency , but the vitamin D status that fully normalizes absorption is not known for humans . Objective : To quantify calcium absorption at two levels of vitamin D repletion , using pharmacokinetic methods and commercially marketed calcium supplements . Design : Two experiments performed in the spring of the year , one year apart . In the first , in which participants were pretreated with 25-hydroxyvitamin D ( 25OHD )  , mean serum 25OHD concentration was 86.5 nmol/L ; and in the other , with no pretreatment , mean serum concentration was 50.2 nmol/L. Participants received 500 mg oral calcium loads as a part of a st and ard low calcium breakfast . A low calcium lunch was provided at mid-day . Blood was obtained fasting and at frequent intervals for 10 to 12 hours thereafter . Methods : Relative calcium absorption at the two 25OHD concentrations was estimated from the area under the curve ( AUC ) for the load-induced increment in serum total calcium . Results : AUC9 ( ± SEM ) , was 3.63 mg hr/dL ± 0.234 in participants pretreated with 25OHD  and 2.20 ± 0.240 in those not pretreated ( P < 0.001 ) . In brief , absorption was 65 % higher at serum 25OHD levels averaging 86.5 nmol/L than at levels averaging 50 nmol/L ( both values within the nominal reference range for this analyte ) . Conclusions : Despite the fact that the mean serum 25OHD level in the experiment without supplementation was within the current reference ranges , calcium absorptive performance at 50 nmol/L was significantly reduced relative to that at a mean 25OHD level of 86 nmol/L. Thus , individuals with serum 25-hydroxyvitamin D levels at the low end of the current reference ranges may not be getting the full benefit from their calcium intake . We conclude that the lower end of the current reference range is set too low OBJECTIVE Inconsistent effects of vitamin A supplementation on prevention of  bronchopulmonary dysplasia  have been reported . Meta- analysis of these reports result ed in a relative risk of 0.69 - 1.02 for death or bronchopulmonary dysplasia associated with vitamin A supplementation . Effective dosage regimens or serum retinol concentrations have not been determined in previous reports . The purpose of this pilot study was to define a vitamin A regimen that produces serum retinol concentrations of 25 - 55 micrograms/dl . STUDY DESIGN In this three-phase study , 91 infants ( mean birth weight 799 - 864 g ) were enrolled .  Vitamin A was administered three times/week for 4 weeks at an average daily dose of 986 - 2143 IU/day . Physical examinations were performed and serum retinol specimens were collected weekly to assess clinical signs of toxicity . RESULTS The majority of serum retinol concentrations remained < 25 micrograms/dl until an intramuscular vitamin A dose of 5000 IU/dose three times/week was used . No clinical signs of toxicity were associated with the higher dosage and higher serum concentrations of vitamin A. CONCLUSION A large clinical trial of vitamin A supplementation with 5000 IU/dose three times/week ( 25 - 114 % more than the dose used in the three published clinical trials ) is needed to assess whether vitamin A supplementation  safely reduces the risk of bronchopulmonary dysplasia  in very-low-birth-weight infants Objective : Indoor athletes have been shown to be prone to vitamin D3 deficiency . The aim of the study was to examine the acute effects of vitamin D supplementation on muscle function using isokinetic dynamometry . Design : R and omized placebo-controlled , double-blind study . Setting : Institutional . Participants : Adult male white national level judoka athletes ( n = 22 ) who were involved in full-time training . Exclusion criteria were vitamin supplementation , overseas travel to sunny climes , and /or an injury incurred during the last 3 months before testing . Interventions : Subjects were r and omly allocated to the treatment ( 150 000IU vitamin D3 ) or placebo and given blinded supplements by an independent research er . Participants were tested twice , 8 days apart , on a Monday morning before the start of judo training and after 2 days of rest . A 5 to 7 mL of blood sample was collected followed by isokinetic concentric quadriceps and hamstring muscle function assessment s on the right leg at 30 and 200 ° ·s−1 . Main Outcome Measures : Repeated- measures analysis of variance was used to analyze isokinetic muscle force and serum 25(OH)D3 . Regression to the mean was used to examine changes in 25(OH)D3 levels over the study period . Results : The treatment group demonstrated a significant increase in serum 25(OH)D levels ( 34 % , P ⩽ 0.001 ) and muscle strength ( 13 % , P = 0.01 ) between days 1 and 8 . No significant differences were found for the placebo group for the same period . Conclusions : A single bolus of 150 000IU vitamin D3 had a significant positive effect on serum 25(OH)D levels and muscle function in vitamin D insufficient elite indoor athletes . Clinical Relevance : Serum 25(OH)D3 levels of indoor athletes should be monitored throughout the year and especially during winter months . Beneficial responses , in muscle strength and serum 25(OH)D3 , to 1 dose of vitamin D3 supplementation can be observed within 1 week of ingestion . Muscle strength is linked to serum 25(OH)D levels Summary On September 29 , 2011 , acknowledged experts in the field of vitamin D , mainly European , were brought together in order to discuss the recent scientific advances in relation to vitamin D : the current requirements and associations with various health outcomes . In this article , the discussion s result ing from the meeting are summarized . Introduction Several groups at risk for developing vitamin D insufficiency have been identified . Accordingly , review s indicate that a significant percentage of the population worldwide have serum 25-hydroxyvitamin D levels below 50 nmol/l . In addition to the role of vitamin D in bone health , recent studies suggest that it may play a pivotal role in other systems , e.g. , the cardiovascular system , pancreas , muscle , immune system and brain . Most evidence , however , is obtained from observational studies and yet inconclusive . Methods To exchange and broaden knowledge on the requirements for vitamin D and its effect on various health outcomes , a workshop entitled “ Vitamin D Expert Meeting : Do we get enough ? ” , was organized . Results Despite low vitamin D levels worldwide , consensus on the definition of deficiency is not yet reached . In order to define cut-off points for vitamin D whilst taking into account extraskeletal health effects , r and omized controlled trials in these fields are warranted . The experts do emphasize that there is evidence to suggest an important role for vitamin D in the maintenance of optimal bone health at all ages and that vitamin D supplementation , in most studies co-administered with calcium , reduces fracture risk in the senior population . Conclusion To reach a serum 25-hydroxyvitamin D level of 50 nmol/l older adults aged ≥65 years are therefore recommended to meet a mean daily vitamin D intake of 20 μg ( 800 IU ) , which is best achieved with a supplement BACKGROUND Eczema is one of the most common chronic inflammatory skin diseases , affecting about 20 % of children . The pathogenic mechanisms of eczema are still not fully understood , and current treatment of moderate-severe eczema is often difficult . Recently , it has been suggested that Vitamin D plays a key role in this disease , even if mechanisms are only partially known . OBJECTIVE The purpose of our study was to assess the  25-Hydroxyvitamin D serum levels in a pediatric population suffering from chronic eczema ( IgE-mediated and non-IgE-mediated ) , and to correlate these phenotypes with the SCORAD severity and selected clinical and biological parameters . Moreover , we aim ed to evaluate whether a supplementation of Vitamin D3 could affect the same clinical and laboratory parameters . METHODS 89 children with chronic eczema were enrolled in the study . Severity of eczema was assessed with the SCORAD index . Past and present history was taken , and patients were divided into two groups according to the state of sensitization . According to a r and omization schedule , the enrolled children were assigned to the following groups : supplementation group , which received a daily oral Vitamin D3 supplementation ( 2000 IUs ) for 3 months ; control group which received no supplementation . RESULTS  Vitamin D concentrations in patients with moderate and severe eczema were not statistically different from Vitamin D concentration detected in the serum of patients with mild eczema . Furthermore , we did not find any correlation between Vitamin D levels , total IgEs and SCORAD index , both in the Sensitized and in the Not-Sensitized group . The Vitamin D3 supplementation did not influence the SCORAD severity or the total IgEs concentration . CONCLUSION To our knowledge , our study is the first one that shows no correlation between serum levels of Vitamin D , eczema severity and IgE sensitization in a pediatric population suffering from chronic eczema Importance Whether vitamin D supplementation during pregnancy is beneficial and safe for offspring is unclear . Objective To systematic ally review studies of the effects of vitamin D supplementation during pregnancy on offspring growth , morbidity  , and mortality . Data Sources Search es of Medline , Embase , and the Cochrane Data base of Systematic Review s were conducted up to October 31 , 2017 . Key search terms were vitamin D , pregnancy , r and omized controlled trials , and offspring outcomes . Study Selection R and omized clinical trials of vitamin D supplementation during pregnancy and offspring outcomes . Data Extraction and Synthesis Two authors independently extracted data , and the quality of the studies was assessed . Summary risk ratio ( RR ) , risk difference ( RD ) or mean difference ( MD ) , and 95 % CI were calculated using fixed-effects or r and om-effects meta- analysis . Main Outcomes and Measures Main outcomes were fetal or neonatal mortality , small for gestational age ( SGA ) , congenital malformation , admission to a neonatal intensive care unit , birth weight , Apgar scores , neonatal 25-hydroxyvitamin D ( 25[OH]D ) and calcium concentrations , gestational age , preterm birth , infant anthropometry , and respiratory morbidity during childhood . Results Twenty-four clinical trials involving 5405 participants met inclusion criteria . Vitamin D supplementation during pregnancy was associated with a lower risk of SGA ( RR , 0.72 ; 95 % CI , 0.52 to 0.99 ; RD , −5.60 % ; 95 % CI , −0.86 % to −10.34 % ) without risk of fetal or neonatal mortality ( RR , 0.72 ; 95 % CI , 0.47 to 1.11 ) or congenital abnormality ( RR , 0.94 ; 95 % CI , 0.61 to 1.43 ) . Neonates with prenatal vitamin D supplementation had higher 25(OH)D levels ( MD , 13.50 ng/mL ; 95 % CI , 10.12 to 16.87 ng/mL ) , calcium levels ( MD , 0.19 mg/dL ; 95 % CI , 0.003 to 0.38 mg/dL ) , and weight at birth ( MD , 75.38 g ; 95 % CI , 22.88 to 127.88 g ) , 3 months ( MD , 0.21 kg ; 95 % CI , 0.13 to 0.28 kg ) , 6 months ( MD , 0.46 kg ; 95 % CI , 0.33 to 0.58 kg ) , 9 months ( MD , 0.50 kg ; 95 % CI , 0.01 to 0.99 kg ) , and 12 months ( MD , 0.32 kg ; 95 % CI , 0.12 to 0.52 kg ) . Subgroup analysis by doses showed that low-dose vitamin D supplementation ( ⩽2000 IU/d ) was associated with a reduced risk of fetal or neonatal mortality ( RR , 0.35 ; 95 % CI , 0.15 to 0.80 ) , but higher doses ( > 2000 IU/d ) did not reduce this risk ( RR , 0.95 ; 95 % CI , 0.59 to 1.54 ) . Conclusions and Relevance Vitamin D supplementation during pregnancy is associated with a reduced risk of SGA and improved infant growth without risk of fetal or neonatal mortality or congenital abnormality . Vitamin D supplementation with doses of 2000 IU/d or lower during pregnancy may reduce the risk of fetal or neonatal mortality 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 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 OBJECTIVE . Vitamin D insufficiency occurs commonly in HIV-infected youth in the United States . In light of the importance of vitamin D for skeletal and nonskeletal health , including innate immunity , developing methods for improving vitamin D status in HIV-infected children and adolescents is an important area of clinical research . The objective of this study was to evaluate the effect of administration of oral cholecalciferol , 100000 IU every 2 months , and 1 g/day calcium on serum 25-hydroxyvitamin D concentrations , serum and urine calcium , and HIV disease progression during a 12-month period . METHODS . HIV-infected children and adolescents who were aged 6 to 16 years were r and omly assigned to receive vitamin D ( 100000 IU bimonthly ) and calcium ( 1 g/day ; n = 29 ) or double placebo ( n = 27 ) . Serum 25-hydroxyvitamin D concentrations as measured by radioimmunoassay , albumin-corrected calcium concentrations , and spot urinary calcium-creatinine ratios were determined monthly . RESULTS . No abnormalities in serum calcium concentration were observed . One participant who received placebo  developed hypercalciuria . No group differences were seen in the change in CD4 count or CD4 % or viral load during 12 months . The overall mean monthly serum 25-hydroxyvitamin D concentrations were higher in the group that received vitamin D and calcium than in the placebo group , as was the monthly serum 25-hydroxyvitamin D area under the curve . After completing 12 months of study , 2 ( 6.7 % ) participants in the group that received vitamin D and calcium had a trough serum 25-hydroxyvitamin D concentration < 20 ng/mL compared with 14 ( 50 % ) in the placebo group . Twelve ( 44.4 % ) in the group that received vitamin D and calcium  had a trough serum 25-hydroxyvitamin D concentration of ≥30 ng/mL compared with 3 ( 11.1 % ) in the placebo group . CONCLUSIONS . Administration of oral cholecalciferol to HIV-infected children and adolescents at a dosage of 100000 IU every 2 months , together with 1 g/day calcium , is safe and results in significant increases in serum 25-hydroxyvitamin D concentrations BACKGROUND We previously found a high prevalence of vitamin D deficiency and low medication regimen compliance in Arab and East Indian women residing in the United Arab Emirates ( UAE ) . The appropriate dosing regimen for improving vitamin D status in this population is not known . OBJECTIVE We aim ed to determine the efficacy of daily and monthly supplementation with vitamin D2 , the only high-dose calciferol available in the UAE , in lactating and nulliparous women . DESIGN Healthy lactating ( n = 90 ) and nulliparous ( n = 88 ) women were r and omly assigned to consume 2000 IU vitamin D2/d or 60,000 IU vitamin D2/mo for 3 mo . Serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations were measured by radioimmunoassay at baseline and every month . RESULTS Most women had vitamin D deficiency [ ie , 25(OH)D < 50 nmol/L ] at study entry . Mean + /- SD 25(OH)D concentrations at 3 mo were significantly higher than baseline in both lactating ( 39.8 + /- 12.4 and 25.2 + /- 10.7 nmol/L , respectively ) and nulliparous ( 40.4 + /- 23.4 and 19.3 + /- 12.2 nmol/L , respectively ) women ( P < 0.001 for both ) . In total , vitamin D supplementation was effective in achieving serum 25(OH)D concentrations of > or=50 nmol/L in 21 ( 30 % ) of 71 women at endpoint . CONCLUSIONS Oral vitamin D2 supplementation with 2000 IU/d or 60,000 IU/mo for 3 mo was safe , and it increased serum 25(OH)D concentrations significantly ; however , only a small proportion of the women studied achieved concentrations of > or=50 nmol/L. This suggests that , when sunlight exposure is limited , doses of vitamin D2 higher than those currently studied may be needed . Monthly dosing appears to be a safe and effective alternative to daily dosing BACKGROUND There is increasing interest in the extraskeletal effects of vitamin D , particularly in the obese state with regard to the development of insulin resistance and diabetes . OBJECTIVE The objective of the study was to determine the effect of 2 doses of cholecalciferol ( vitamin D3 ) supplementation on insulin action ( Si ) and pancreatic β-cell function in obese adolescents . METHODS We performed a 12-wk double-blind , r and omized comparison of the effect of vitamin D3 supplementation on Si and β-cell function in obese Caucasian adolescents ( body mass index > 95(th ) percentile ) . The subjects were r and omly assigned to receive either 400 IU/d ( n = 25 ) or 2000 IU/d ( n = 26 ) of vitamin D3 . Each subject underwent a 7- sample 75 g oral glucose tolerance test , with glucose , insulin , and C-peptide measurements , to calculate Si and β-cell function as assessed by the disposition index ( DI ) , with use of the oral minimal model before and after supplementation . A total of 51 subjects aged 15.0 ± 1.9 y were enrolled . Included for analysis at follow-up were a total of 46 subjects ( 20 male and 26 female adolescents ) , 23 in each group .  RESULTS Initial serum 25-hydroxyvitamin D [ 25(OH)D ] was 24.0 ± 8.1 μg/L. There was no correlation between 25(OH)D concentrations and Si or DI . There was a modest but significant increase in 25(OH)D concentration in the 2000 IU/d group ( 3.1 ± 6.5 μg/L , P = 0.04 ) but not in the 400 IU/d group ( P = 0.39 ) . There was no change in Si or DI  following vitamin D3 supplementation in either of the treatment groups ( all P > 0.10 ) . CONCLUSIONS The current study shows no effect from vitamin D3 supplementation , irrespective of its dose , on β-cell function or insulin action in obese nondiabetic adolescents with relatively good vitamin D status . Whether obese adolescents with vitamin D deficiency and impaired glucose metabolism would respond differently to vitamin D3 supplementation remains unclear and warrants further studies . This trial was registered at clinical trials.gov as NCT00858247 There is mounting evidence that periodontal disease ( PD ) is linked to low serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations in addition to recognized risk factors like diet and smoking . This paper review s this evidence using Hill 's criteria for causality in a biological system . Evidence for strength of association , consistency , cohesion and ' dose-effects ' [ biological ' gradients ' ] include strong inverse correlations between serum 25(OH ) and both PD cross-sectionally and that PD is consistently more prevalent in darker vs. lighter skinned people and increases at higher latitudes with analogy for gingivitis and for disorders associated with PD whose risks increase with hypovitaminosis D. Evidence for plausibility includes that vitamin D increases calcium absorption and protects bone strength ; induces formation of cathelicidin and other defensins that combat bacterial infection ; reduces tissue production of destructive matrix metalloproteinases actively associated with PD and that prevalence of PD varies with common vitamin D receptor polymorphisms . Experimental evidence from limited supplementation studies [ using calcium and vitamin D ] shows that supplementation reduces tooth loss . Thus , existing evidence for hypovitaminosis D as a risk factor for PD to date meets Hill 's criteria for causality in a biological system . Further experimental evidence for effectiveness and temporality , preferably from r and omized controlled trials of vitamin D supplementation [ adjusting for other PD risk factors including diet and smoking to reduce confounding ] are necessary to confirm causality . If confirmed , dentists and periodontists could perform a valuable service to their patients by discussing the importance of adequate vitamin D status and on how to avoid deficiency Introduction Optimal vitamin D status promotes skeletal health and is recommended with specific treatment in individuals at high risk for fragility fractures . A growing body of literature has provided indirect and some direct evidence for possible extraskeletal vitamin D-related effects . Purpose and Methods Members of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis have review ed the main evidence for possible proven benefits of vitamin D supplementation in adults at risk of or with overt chronic extra-skeletal diseases , providing recommendations and guidelines for future studies in this field . Results and conclusions Robust mechanistic evidence is available from in vitro studies and in vivo animal studies , usually employing cholecalciferol , calcidiol or calcitriol in pharmacologic rather than physiologic doses . Although many cross-sectional and prospect i ve association studies in humans have shown that low 25-hydroxyvitamin D levels ( i.e. , < 50 nmol/L ) are consistently associated with chronic diseases , further strengthened by a dose-response relationship , several meta-analyses of clinical trials have shown contradictory results . Overall , large r and omized controlled trials with sufficient doses of vitamin D are missing , and available small to moderate-size trials often included people with baseline levels of serum 25-hydroxyvitamin D levels  > 50 nmol/L , did not simultaneously assess multiple outcomes , and did not report overall safety ( e.g. , falls ) . Thus , no recommendations can be made to date for the use of vitamin D supplementation in general , parental compounds , or non-hypercalcemic vitamin D analogs in the prevention and treatment of extra-skeletal chronic diseases . Moreover , attainment of serum 25-hydroxyvitamin D levels well above the threshold desired for bone health can not be recommended based on current evidence , since safety has yet to be confirmed . Finally , the promising findings from mechanistic studies , large cohort studies , and small clinical trials obtained for autoimmune diseases ( including type 1 diabetes , multiple sclerosis , and systemic lupus erythematosus ) , cardiovascular disorders , and overall reduction in mortality require further confirmation
Both doses led to sufficiency concentrations during winter months .
Among athletes with baseline vitamin D suggesting sufficiency , serum 25(OH)D sufficiency was maintained from different doses at both latitudes .
Conclusion Despite achieving sufficiency in vitamin D concentrations from ≥3000 IU supplementation , physical performance did not significantly improve .
Background There is currently no systematic review examining the effects of vitamin D supplementation  among athletes .
A rigorous systematic review and meta- analysis is important to provide a balanced view of current knowledge on the effect of vitamin D on serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations and physical performance .
Objectives This systematic review of r and omized controlled trials ( RCTs ) evaluated the effects of oral vitamin D supplementation on serum 25(OH)D concentrations and physical performance in athletes .