Plasma 25-Hydroxyvitamin D Levels and Risk of Incident Hypertension Associations between 25-hydroxyvitamin D and weight gain in elderly women. Plasma Vitamin D and 25OHD Responses of Young and Old Men to Supplementation with Vitamin D3 Body Size and Serum 25 Hydroxy Vitamin D Response to Oral Supplements in Healthy Older Adults A 16-week randomized clinical trial of 2000 international units daily vitamin D3 supplementation in black youth: 25-hydroxyvitamin D, adiposity, and arterial stiffness. Vitamin d and physical activity status: associations with five-year changes in body composition and muscle function in community-dwelling older adults. Serum concentrations of 1,25-dihydroxyvitamin D2 and 1,25-dihydroxyvitamin D3 in response to vitamin D2 and vitamin D3 supplementation. Cross-sectional and longitudinal relation between serum 25-hydroxyvitamin D and body mass index: the Tromsø study High-dose vitamin d intervention in infants--effects on vitamin d status, calcium homeostasis, and bone strength. Large Doses of Vitamin D Fail to Increase 25-Hydroxyvitamin D Levels or to Alter Cardiovascular Risk Factors in Obese Adolescents: A Pilot Study. Effect of adiposity on vitamin D status and the 25-hydroxycholecalciferol response to supplementation in healthy young and older Irish adults. Vitamin D3 dose requirement to raise 25-hydroxyvitamin D to desirable levels in adolescents: results from a randomized controlled trial. Effect of free vitamin D2 drops on serum 25-hydroxyvitamin D in infants with immigrant origin: a cluster randomized controlled trial High-dose oral vitamin D3 supplementation in the elderly Standardizing serum 25-hydroxyvitamin D data from four Nordic population samples using the Vitamin D Standardization Program protocols: Shedding new light on vitamin D status in Nordic individuals Medium doses of daily vitamin D decrease falls and higher doses of daily vitamin D3 increase falls: A randomized clinical trial Vitamin D supplementation in young White and African American women.
Hydroxylation of 25(OH)D to 1,25-dihydroxyvitamin D and signaling through the vitamin D receptor occur in various tissues not traditionally involved in calcium homeostasis . Laboratory studies indicate that 1,25-dihydroxyvitamin D suppresses renin expression and vascular smooth muscle cell proliferation ; clinical studies demonstrate an inverse association between ultraviolet radiation , a surrogate marker for vitamin D synthesis , and blood pressure . We prospect ively studied the independent association between measured plasma 25-hydroxyvitamin D [ 25(OH)D ] levels and  risk of incident hypertension  and also the association between predicted plasma 25(OH)D levels and risk of incident hypertension .  Two prospect i ve cohort studies including 613 men from the Health Professionals ’ Follow-Up Study and 1198 women from the Nurses ’ Health Study with measured 25(OH)D levels were followed for 4 to 8 years . In addition , 2 prospect i ve cohort studies including 38 388 men and 77 531 women with predicted 25(OH)D levels were followed for 16 to 18 years . During 4 years of follow-up , the multivariable relative risk of incident hypertension among men whose measured plasma 25(OH)D levels were < 15 ng/mL ( ie , vitamin D deficiency ) compared with those whose levels were ≥30 ng/mL was 6.13 ( 95 % confidence interval [ CI ] : 1.00 to 37.8 ) . Among women , the same comparison yielded a relative risk of 2.67 ( 95 % CI : 1.05 to 6.79 ) . The pooled relative risk combining men and women with measured 25(OH)D levels using the r and om-effects model was 3.18 ( 95 % CI : 1.39 to 7.29 ) . Using predicted 25(OH)D levels in the larger cohorts , the multivariable relative risks comparing the lowest to highest deciles were 2.31 ( 95 % CI : 2.03 to 2.63 ) in men and 1.57 ( 95 % CI : 1.44 to 1.72 ) in women . Plasma 25(OH)D levels are inversely associated with risk of incident hypertension BACKGROUND 25-Hydroxyvitamin D [ 25(OH)D ] levels are lower in obese individuals . Determining whether low vitamin D status can predispose weight gain requires a longitudinal study . METHODS From a community-based multicenter U.S. prospect i ve cohort of 9704 ( Study of Osteoporotic Fractures [ SOF ] ) , 4659 women aged ≥65 with baseline 25(OH)D measurement were followed for 4.5 years . They were weighed at baseline and follow-up visits , and a subset ( n=1054 ) had 25(OH)D levels remeasured at follow-up . RESULTS Women with 25(OH)D levels ≥30 ng/mL had lower baseline weight ( 141.6 pounds ) compared to women with 25(OH)D levels < 30 ng/mL ( 148.6 pounds ) ( p<0.001 ) . Overall , 25(OH)D status was not associated with weight change over 4.5 years , although there was a significant interaction between 25(OH)D status and weight change category ( loss , gain , stable ) ( p<0.0001 ) . In women who gained ≥5 % weight , those with baseline 25(OH)D levels ≥30 ng/mL gained 16.4 pounds ( 12.2 % of baseline weight ) over 4.5 years compared to 18.5 pounds ( 13.9 % of baseline weight ) in women with levels < 30 ng/mL ( p=0.04 ) . In women who lost ≥5 % weight or remained stable ( < 5 % weight change ) , there was no association between 25(OH)D status at baseline and weight change . Among women who gained weight and had 25(OH)D measured at both visits , having sustained or developing 25(OH)D levels ≥30 ng/mL was associated with less weight gain between visits ( 14.81 vs. 16.34 pounds , p=0.04 ) . CONCLUSIONS Higher 25(OH)D levels are associated with lower weight gains , suggesting low vitamin D status may predispose to fat accumulation Objectives : This study was conducted to determine whether there are age differences in the plasma parent vitamin D and 25-hydroxyvitamin D ( 25OHD ) responses to eight weeks of supplementation with 20 μg/day of vitamin D3 . Methods : Twenty-five healthy young men ( age 18–35 ) and 25 healthy older men ( 62–79 ) were r and omly assigned to supplementation with 20 μg/day of vitamin D3 or to no intervention and followed for eight weeks . Plasma vitamin D3 was measured by high performance liquid chromatography and 25OHD was measured by competitive protein binding . Results : Both young and old men in the supplemented group had pronounced , rapid and similar increases in plasma vitamin D3 , whereas vitamin D3 concentrations were stable in the control group . By the end of the eight-week adaptation period , plasma vitamin D3 of young and old men had increased by 4.3 and 6.2 nmol/L respectively . In the supplemented group , mean 25OHD concentrations of both the young and old men increased during the study , and the magnitude of the change after eight weeks was nearly identical in the two age groups ( 22.5 and 22.1 nmol/L in the young and the old men , respectively ) . In the control group there was a modest decrease in 25OHD of both the young and old men . Conclusions : There appears to be no age-related impairment among men in the absorption or metabolism of 20 μg/day of vitamin D3 taken orally for at least eight weeks Background : Vitamin D insufficiency is prevalent in the northeast United States . Since vitamin D insufficiency is readily amenable to supplementation , it is important to underst and what factors are associated with serum 25 hydroxy vitamin D ( 25(OH)D ) response to vitamin D supplementation . Objective : In this study we examined the association of serum 25(OH)D response to vitamin D supplementation with body size in a population of elderly subjects . Methods : 257 healthy , ambulatory men and women 65 years of age or older were r and omly assigned to treatment with either 700 IU/day ( 17.5 μg/d ) of supplemental vitamin D3 and 500 mg/day ( 12.5 mmol/d ) of supplemental calcium , or to placebo . Results : In multivariate regression analyses , after adjusting for baseline 25(OH)D , season , and sex , we found change in 25(OH)D to be inversely associated with baseline BMI ( p = 0.01 ) in subjects treated with supplements for one year . Change in 25(OH)D was also negatively associated with other baseline anthropometric measurements in these subjects . Conclusion : Our study implies that body size should be taken into account when estimating the amount of vitamin D intake needed to raise 25(OH)D to the desired level CONTEXT Vitamin D insufficiency/deficiency is commonly observed in black youth . OBJECTIVE The aim was to determine 25-hydroxyvitamin D [ 25(OH)D ] in response to 2000 IU vitamin D supplementation over time ; to evaluate the relation between 25(OH)D concentrations and total body fat mass by dual-energy x-ray absorptiometry ; and to determine whether vitamin D supplementation improves arterial stiffness measured by pulse wave velocity ( PWV ) . DESIGN We conducted a r and omized , blinded , controlled clinical trial . SETTING AND PARTICIPANTS Forty-nine normotensive black boys and girls , aged 16.3 ± 1.4 yr , were r and omly assigned to either the control group ( 400 IU/d ; n = 24 ) or the experimental group ( 2000 IU/d ; n = 25 ) . RESULTS Plasma 25(OH)D values at baseline and at 4 , 8 , and 16 wk were 34.0 ± 10.6 , 44.9 ± 9.4 , 51.2 ± 11.1 , and 59.8 ± 18.2 nmol/liter , respectively , for the control group ; and 33.1 ± 8.7 , 55.0 ± 11.8 , 70.9 ± 22.0 , and 85.7 ± 30.1 nmol/liter , respectively , for the experimental group . The experimental group vs. the control group reached significantly higher 25(OH)D concentrations at 8 and 16 wk , respectively . Partial correlation analyses indicated that total body fat mass at baseline was significantly and inversely associated with 25(OH)D concentrations in response to the 2000-IU supplement across time . Furthermore , carotid-femoral PWV increased from baseline ( 5.38 ± 0.53 m/sec ) to posttest ( 5.71 ± 0.75 m/sec ) in the control group ( P = 0.016 ) , whereas in the experimental group carotid-femoral PWV decreased from baseline ( 5.41 ± 0.73 m/sec ) to posttest ( 5.33 ± 0.79 m/sec ) ( P = 0.031 ) . CONCLUSION Daily 2000 IU vitamin D supplementation may be effective in optimizing vitamin D status and counteracting the progression of aortic stiffness in black youth . Plasma 25(OH)D concentrations in response to the 2000 IU/d supplementation are negatively modulated by adiposity CONTEXT High vitamin D and physical activity ( PA ) levels are independently associated with improved body composition and muscle function in older adults . OBJECTIVE The objective of this study was to investigate the interaction of 25-hydroxyvitamin D ( 25OHD ) and PA status in maintenance of body composition and muscle function in older adults . DESIGN AND SETTING This was a 5-year prospect i ve population -based study of Australian community-dwelling older adults . PARTICIPANTS Participants in the study included 615 community-dwelling volunteers aged 50 years old or older [ 61.4 ± 6.9 ( mean ± SD ) y ; 48 % female ] r and omly selected from electoral rolls and categorized according to baseline serum 25OHD ( ≥ or < 50 nmol/L ) and PA ( ≥ or < 10,000 pedometer determined steps/d ) levels as follows : high 25OHD and high PA ( VitD+PA+ ) ; high 25OHD and low PA ( VitD+PA- ) ; low 25OHD and high PA ( VitD-PA+ ) ; and low 25OHD and low PA ( VitD-PA- ) . A subset of 518 participants completed accelerometer assessment s during follow-up . MAIN OUTCOME MEASURES Changes in dual-energy X-ray absorptiometry-assessed body composition and lower-limb muscle function were measured . RESULTS VitD+PA+ had significantly smaller increases in body fat over 5 years compared with other groups ( all P < .05 ) . Higher baseline pedometer-determined PA result ed in declines in total body fat ( β = -.23 kg per 100 steps/d , P = .001 ) over 5 years for participants with high 25OHD but not those with low 25OHD ( P > .05 ) . Among participants with accelerometer data , these associations were generally mediated by higher levels of moderate/vigorous PA . CONCLUSIONS High vitamin D status appears to enhance PA-related declines in body fat during aging , but the mechanism may be greater amounts of outdoor moderate/vigorous PA rather than a direct effect of 25OHD OBJECTIVE The purpose of this study was to determine 1,25-dihydroxyvitamin D3 [ 1,25(OH)2D3 ] and 1,25-dihydroxyvitamin D2 [ 1,25(OH)2D2 ] levels in healthy adults consuming 1000 IU vitamin D2 or vitamin D3 per day for 11 weeks . SUBJECTS AND DESIGN Blood from 34 healthy male and female adults , aged 18 to 79 years , from a placebo-controlled , double-blind study who received a placebo , 1000 IU vitamin D3 , or 1000 IU vitamin D2 daily for 11 weeks at end of winter was analyzed . Serum levels of 25-hydroxyvitamin D2 , 25-hydroxyvitamin D3 , 1,25(OH)2D2 , and 1,25(OH)2D3  were determined by liquid chromatography-t and em mass spectroscopy . RESULTS Of the adults , 82 % were vitamin D insufficient ( serum 25-hydroxyvitamin D [ 25(OH)D < 30 ng/mL ] ) at the start of the study . Administration of vitamin D2 and vitamin D3 induced similar increases in total 25(OH)D as well as in 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 , respectively . Compared with placebo and adjusting for baseline levels , 1000 IU daily of vitamin D2 was associated with a mean increase of 7.4 pg/mL ( 95 % confidence interval , 4.4 - 10.3 ) in 1,25(OH)2D2 , which was accompanied by a mean decrease of 9.9 pg/mL ( -15.8 to -4.0 ) in 1,25(OH)2D3 . No such differences accompanied administration of 1000 IU daily of vitamin D3 . CONCLUSION Vitamin D2 and vitamin D3 were effective in raising and maintaining total serum concentrations of 25(OH)D. Ingestion of vitamin D2 also result ed in an increase in serum concentrations of 1,25(OH)2D2 . This increase was accompanied by a comparable decrease in serum concentrations of 1,25(OH)2D3 ; therefore , the total 1,25-dihydroxyvitamin D [ 1,25(OH)2D ] concentrations did not significantly change after 11 weeks compared with baseline levels . Ingestion of vitamin D3 did not alter serum concentrations of 1,25(OH)2D3 or total 1,25(OH)2D . Therefore , ingestion of 1000 IU vitamin D2 or vitamin D3 for 11 weeks was effective in raising total serum concentrations of 25(OH)D as well as sustaining serum concentrations of total 1,25(OH)2D Purpose The serum 25-hydroxyvitamin D ( 25(OH)D ) levels are lower in obese than lean subjects . The present study examines the cross-sectional and longitudinal relations between body mass index ( BMI ) and serum 25(OH)D , and the serum 25(OH)D response to vitamin D supplementation  in relation to BMI . Methods The Tromsø study is a longitudinal population -based multi purpose study . The fourth survey was conducted in 1994 and the sixth in 2008 . The intervention study was a 1-year placebo-controlled r and omized intervention trial , where the results from the 93 subjects given 40,000 IU per week are presented . Results A total of 10,229 subjects were included in the 2008 cross-sectional study . There was a significant negative association between serum 25(OH)D levels and BMI which was also present during the winter months . Serum 25(OH)D levels varied through seasons , but not BMI . In the longitudinal study from 1994 to 2008 which included 2,656 subjects , change in BMI was a significant negative predictor of change in 25(OH)D. In the intervention study , there was a significant and negative correlation between BMI and serum 25(OH)D both at baseline and at the end of the study . The increase in serum 25(OH)D after 1 year was significantly and inversely related to baseline BMI . Conclusions We have confirmed the strong association between serum 25(OH)D and BMI . The very obese need higher vitamin D doses than lean subjects to achieve the same serum 25(OH)D levels CONTEXT Guidelines in Finl and recommend 10 μg of vitamin D3 daily for all infants . Recent observations suggest that this may be insufficient to maintain optimal serum 25-hydroxyvitamin D ( S-25-OHD ) . OBJECTIVE The aim of the study was to evaluate effects of various vitamin D doses and determine a dose ensuring S-25-OHD of at least 80 nmol/liter in infants without signs of vitamin D excess . DESIGN We conducted a r and omized double-blind intervention study . Cord blood was obtained at birth for S-25-OHD ; 113 infants were r and omized to receive vitamin D3 10 , 30 , or 40 μg/d from age 2 wk to 3 months . SETTING An investigator-initiated study was performed in a single maternity hospital in Helsinki , Finl and . MAIN OUTCOME MEASURES S-25-OHD , calcium homeostasis , and skeletal characteristics were evaluated with peripheral quantitative computed tomography at age 3 months . RESULTS Baseline S-25-OHD was similar in all three groups ( median , 53 nmol/liter ) . At 3 months , the mean S-25-OHD values were 88 , 124 , and 153 nmol/liter , and the minimum values were 46 , 57 , and 86 nmol/liter in the groups receiving 10 , 30 , and 40 μg ( ANOVA ; P < 0.001 ) . No hypercalcemia occurred ; plasma calcium , serum PTH , and urine calcium excretion was similar between the groups . Peripheral quantitative computed tomography showed a trend toward larger tibial total bone and cortical bone area with higher vitamin D doses . CONCLUSION Vitamin D3 supplementation with up to 40 μg/d from age 2 wk to 3 months was safe and caused no hypercalcemia or hypercalciuria . The 40-μg dose maintained S-25-OHD above 80 nmol/liter in all infants . More extensive and longer intervention studies are necessary to assess long-term effects PURPOSE Vitamin D deficiency and cardiometabolic risk factors are common in obese adolescents . Observational studies demonstrate an inverse relationship among serum 25-hydroxyvitamin D ( 25OHD ) and obesity , insulin resistance , and inflammatory cytokines . This pilot study explores if vitamin D supplementation could reduce serum concentrations of inflammatory cytokines ( interleukin [ IL ] 6 , IL-10 , tumor necrosis factor α ) , adiponectin , lipids , hemoglobin A1C , and high-sensitivity C-reactive protein ( hs-CRP ) . A secondary aim was to determine the associations between baseline serum 25OHD concentrations and body mass index ( BMI ) , hs-CRP , inflammatory cytokines , and lipids . METHODS Overweight and obese adolescents enrolled in this 24-week , r and omized , double-blind study were given 150,000 IU ergocalciferol or placebo at baseline and 12 weeks . Outcome measurements included serum 25OHD , inflammatory cytokines , adiponectin , hs-CRP , lipids , hemoglobin A1C , and BMI at baseline , 12 , and 24 weeks . RESULTS Of 40 participants , 31 ( 78 % ) completed the study . Mean ± st and ard error 25OHD levels were similar in vitamin D and placebo groups at baseline ( 19.6 ± 5.3 vs. 25.8 ± 10.8 ng/mL ) and 24 weeks ( 20.1 ± 3.4 vs. 24.6 ± 8.4 ng/mL ) . Inflammatory and cardiovascular markers were not significantly different between groups at 24 weeks . Serum 25OHD at baseline was associated with BMI ( r = -.44 [ 95 % confidence interval , -.66 to -.15 ] ) but not with other outcome measures . CONCLUSIONS Supplementation with vitamin D at 150,000 IU every 3 months failed to increase serum 25OHD or alter inflammatory markers and lipids in overweight and obese youth . Further studies are needed to establish the dose of vitamin D required to increase 25OHD and determine potential effects on metabolic risk factors in obese teens There is increasing epidemiological evidence linking sub-optimal vitamin D status with overweight and obesity . Although increasing BMI and adiposity have also been negatively associated with the change in vitamin D status following supplementation , results have been equivocal . The aim of this r and omised , placebo-controlled study was to investigate the associations between anthropometric measures of adiposity and the wintertime serum 25-hydroxycholecalciferol ( 25(OH)D ) response to 15 μg cholecalciferol per d in healthy young and older Irish adults . A total of 110 young adults ( 20 - 40 years ) and 102 older adults ( ≥ 64 years ) completed the 22-week intervention with > 85 % compliance . The change in 25(OH)D from baseline was calculated . Anthropometric measures of adiposity taken at baseline included height , weight and waist circumference ( WC ) , along with skinfold thickness measurements to estimate fat mass ( FM ) . FM was subsequently expressed as FM ( kg ) , FM ( % ) , FM index ( FMI ( FM kg/height m2 ) ) and as a percentage ratio to fat-free mass ( FFM ) . In older adults , vitamin D status was inversely associated with BMI ( kg/m2 ) , WC ( cm ) , FM ( kg and % ) , FMI ( kg/m2 ) and FM : FFM ( % ) at baseline ( r - 0·33 , - 0·36 , - 0·33 , - 0·30 , - 0·33 and - 0·27 , respectively , all P values < 0·01 ) . BMI in older adults was also negatively associated with the change in 25(OH)D  following supplementation ( β - 1·27 , CI - 2·37 , - 0·16 , P = 0·026 ) ; however , no such associations were apparent in younger adults . Results suggest that adiposity may need to be taken into account when determining an adequate wintertime dietary vitamin D intake for healthy older adults residing at higher latitudes Several organizations issued recommendations on desirable serum 25-hydroxy vitamin D [ 25(OH)D ] levels and doses of vitamin D needed to achieve them . Trials allowing the formulation of evidence -based recommendations in adolescents are scarce . We investigated the ability of two doses of vitamin D3 in achieving recommended vitamin D levels in this age group . Post hoc analyses on data from a 1-year double-blind trial that r and omized 336 Lebanese adolescents , aged 13 ± 2 years , to placebo , vitamin D3 at 200 IU/day ( low dose ) , or 2000 IU/day ( high dose ) . Serum 25(OH)D level and proportions of children achieving levels ≥ 20 ng/mL and 30 ng/mL were determined . At baseline , mean 25(OH)D was 15 ± 7 ng/mL , 16.4 ± 7 ng/mL in boys , and 14 ± 8 ng/mL in girls , p=0.003 , with a level ≥ 20 ng/mL in 18 % and ≥ 30 ng/mL in 5 % of subjects . At 1 year , mean levels were 18.6 ± 6.6 ng/mL in the low-dose group , 17.1 ± 6 ng/mL in girls , and 20.2 ± 7 ng/mL in boys , p=0.01 , and 36.3 ± 22.3 ng/mL in the high-dose group , with no sex differences . 25(OH)D increased to ≥ 20 ng/mL in 34 % of children in the low-dose and 96 % in the high-dose group , being higher in boys in the low-dose arm only ; it remained ≥ 30 ng/mL in 4 % of children in the low-dose arm but increased to 64 % in the high-dose arm . Baseline 25(OH)D level , body mass index ( BMI ) , and vitamin D dose assigned were the most significant predictors for reaching a 25(OH)D level ≥ 20 ng/mL and 30 ng/mL. A daily dose of 2000 IU raised 25(OH)D level ≥ 20 ng/mL in 96 % of adolescents ( 98 % boys versus 93 % girls ) . Dose-response studies are needed to determine in a definitive manner the daily allowance of vitamin D for Middle Eastern adolescents with a similar profile Background / Objective : To study whether a free supply of vitamin D2 drops to 6-week-old infants together with tailor-made information h and outs improves the vitamin D status after 7 weeks in the intervention group compared to a control group . Subjects/ Methods : In this cluster r and omized controlled trial in eight child health clinics in Oslo , Norway , 66 healthy infants with Pakistani , Turkish or Somali background were included . The intervention group received daily supplementation of vitamin D drops containing 10 μg ( 400 IU ) of ergocalciferol ( vitamin D2 ) with a tailor-made information brochure about vitamin D and its sources , and instruction on how to administer the drops . They were compared to a control group receiving usual care . The principal outcome measure was increase in serum 25-hydroxyvitamin D ( S-25OHD ) 7 weeks later . S-25OHD was analyzed by high-performance liquid chromatography-ultraviolet-mass spectrometry . Results : Total 78 % ( n=51 ) of the included infants completed the study . At follow-up , S-25OHD was significantly higher in the intervention group than in the control group ( 93.5 versus 72.7 nmol l−1 , P=0.03 ) . The mean increase in S-25OHD adjusted for baseline was 28 nmol l−1 ( 95 % confidence interval 10.9–45.2 , P=0.002 ) higher in the intervention group than in the control group . Among exclusively breastfed infants at baseline , S-25OHD increased by 32.3 nmol l−1 ( P=0.035 ) in the intervention group compared to control group . Conclusion : Free supply of vitamin D drops to 6-week-old infants together with tailor-made information h and outs significantly improved the vitamin D status of infants with immigrant background compared to usual care Summary Daily dosing with vitamin D often fails to achieve optimal outcomes , and it is uncertain what the target level of 25-hydroxyvitamin D should be . This study found that large loading doses of vitamin D3 rapidly and safely normalize 25OHD levels , and that monthly dosing is similarly effective after 3–5 months . With baseline 25OHD > 50 nmol/L , vitamin D supplementation does not reduce PTH levels . Introduction There is concern that vitamin D supplementation doses are frequently inadequate , and that compliance with daily medication is likely to be suboptimal . Methods This r and omized double-blind trial compares responses to three high-dose vitamin D3 regimens and estimates optimal 25-hydroxyvitamin D ( 25OHD ) levels , from changes in parathyroid hormone ( PTH ) , and procollagen type I amino-terminal propeptide ( P1NP ) in relation to baseline 25OHD . Sixty-three elderly participants were r and omized to three regimens of vitamin D supplementation : a 500,000-IU loading dose ; the loading dose plus 50,000 IU/month ; or 50,000 IU/month . Results The Loading and Loading + Monthly groups showed increases in 25OHD of 58 ± 28 nmol/L from baseline to 1 month . Thereafter , levels gradually declined to plateaus of 69 ± 5 nmol/L and 91 ± 4 nmol/l , respectively . In the Monthly group , 25OHD reached a plateau of ~80 ± 20 nmol/L at 3–5 months . There were no changes in serum calcium concentrations . PTH and P1NP were only suppressed by vitamin D treatment in those with baseline 25OHD levels < 50 and < 30 nmol/L , respectively . Conclusions Large loading doses of vitamin D3 rapidly and safely normalize 25OHD levels in the frail elderly . Monthly dosing is similarly effective and safe , but takes 3–5 months for plateau 25OHD levels to be reached Abstract Knowledge about the distributions of serum 25-hydroxyvitamin D ( 25(OH)D ) concentrations in representative population sample s is critical for the quantification of vitamin D deficiency as well as for setting dietary reference values and food-based strategies for its prevention . Such data for the European Union are of variable quality making it difficult to estimate the prevalence of vitamin D deficiency across member states . As a consequence of the widespread , method -related differences in measurements of serum 25(OH)D concentrations , the Vitamin D St and ardization Program ( VDSP ) developed protocol s for st and ardizing existing serum 25(OH)D data from national surveys around the world . The objective of the present work was to apply the VDSP protocol s to existing serum 25(OH)D data from a Danish , a Norwegian , and a Finnish population -based health survey and from a Danish r and omized controlled trial . A specifically-selected subset ( n 100–150 ) of bio-banked serum sample s from each of the studies were reanalyzed for 25(OH)D by LC-MS/MS and a calibration equation developed between old and new 25(OH)D data , and this equation was applied to the entire data -sets from each study . Compared to estimates based on the original serum 25(OH)D data , the percentage vitamin D deficiency ( < 30 nmol/L ) decreased by 21.5 % in the Danish health survey but by only 1.4 % in the Norwegian health survey ; but was relatively unchanged ( 0 % and 0.2 % ) in the Finish survey or Danish RCT , respectively , following VDSP st and ardization . In conclusion , st and ardization of serum 25(OH)D concentrations is absolutely necessary in order to compare serum 25(OH)D concentrations across different study population s , which is needed to quantify and prevent vitamin D deficiency Falls are a serious health problem in the aging population . Because low levels of vitamin D have been associated with increased fall rates , many trials have been performed with vitamin D ; two meta-analyses showed either a small effect or no effect of vitamin D on falls . We conducted a study of the effect of vitamin D on serum 25 hydroxyvitamin D ( 25OHD ) and data on falls was collected as a secondary outcome . In a 12-month double blind r and omized placebo trial , elderly women , mean age 66 years , were r and omized to one of seven daily oral doses of vitamin D or placebo . The main inclusion criterion for study was a baseline serum 25OHD<20ng/ml ( 50nmol/L ) . A history of falls was collected at baseline and fall events were collected every 3 months . Results showed that the effect of vitamin D on falls followed a U-shaped curve whether analyzed by dose or serum 25OHD levels . There was no decrease in falls on low vitamin D doses 400 , 800 IU , a significant decrease on medium doses 1600 , 2400,3200 IU ( p=0.020 ) and no decrease on high doses 4000 , 4800 IU compared to placebo ( p=0.55 ) . When compared to 12-month serum 25OHD quintiles , the faller rate was 60 % in the lowest quintile < 25ng/ml ( < 50nmol/L ) , 21 % in the low middle quintile 32 - 38ng/ml ( 80 - 95nmo/L ) , 72 % in the high middle quintile 38 - 46ng/ml ( 95 - 115nmo/L ) and 45 % in the highest quintile 46 - 66ng/ml ( 115 - 165nmol/L ) . In the subgroup with a fall history , fall rates were 68 % on low dose , 27 % on medium doses and 100 % on higher doses . Fall rates on high doses were increased compared to medium doses ( Odds Ratio 5.6.95 % CI : 2.1 - 14.8 ) . In summary , the maximum decrease in falls corresponds to a 12- month serum 25OHD of 32 - 38ng/ml ( 80 - 95nmol/L ) and faller rates increase as serum 25OHD exceed 40 - 45ng/ml ( 100 - 112.5nmol/L ) . The Tolerable upper limit ( TUL ) recently increased in 2010 from 2000 to 4000 IU/day may need to be reduced in elderly women especially in those with a fall history There is limited information on the effects of vitamin D on serum 25 hydroxyvitamin D ( 25OHD ) in young people and none on African Americans . The main objective of this trial was to measure the effect of different doses of vitamin D3 on serum 25OHD and serum parathyroid hormone ( PTH ) in young women with vitamin D insufficiency ( serum 25OHD ≤ 20 ng/mL ( 50 nmol/L ) . A r and omized double-blind placebo-controlled trial of vitamin D3 was conducted in young white and African American women , age 25 to 45 years . A total of 198 healthy white ( 60 % ) and African American ( 40 % ) women were r and omly assigned to placebo , or to 400 , 800 , 1600 , or 2400 IU of vitamin D3 daily . Calcium supplements were added to maintain a total calcium intake of 1000 to 1200 mg daily . The primary outcomes of the study were the final serum 25OHD and PTH levels at 12 months . The absolute increase in serum 25OHD with 400 , 800 , 1600 , and 2400 IU of vitamin D daily was slightly greater in African American women than in white women . On the highest dose of 2400 IU/d , the mixed model predicted that mean 25OHD increased from baseline 12.4 ng/mL ( 95 % confidence interval [ CI ] , 9.2 - 15.7 ) to 43.2 ng/mL ( 95 % CI , 38.2 - 48.1 ) in African American women and from 15.0 ng/mL ( 95 % CI , 12.3 - 17.6 ) to 39.1 ng/mL ( 95 % CI , 36.2 - 42.0 ) in white women . There was no significant effect  of vitamin D dose on serum PTH in either race but there was a significant inverse relationship between final serum PTH and serum 25OHD . Serum 25OHD exceeded 20 ng/mL in 97.5 % of whites on the 400 IU/d dose and between 800 and 1600 IU/d for African Americans . The recommended dietary allowance ( RDA ) suggested by the Institute of Medicine for young people is 600 IU daily . The increase in serum 25OHD  after vitamin D supplementation was similar in young and old , and in white and African American women
Conclusions This systematic review demonstrates that body weight is an important predictor of variation in circulating 25OHD in cohorts on vitamin D supplements .
Our model provides an estimate of the daily vitamin D dose that is necessary for achieving adequate circulating 25OHD levels in vitamin D-insufficient or vitamin D-deficient individuals/cohorts with different body weights and ages
Purpose There is considerable variation in incremental circulating 25-hydroxyvitamin D ( 25OHD ) levels on vitamin D supplements , even when similar age groups and identical vitamin D doses are compared .
We therefore aim ed to investigate the importance of body weight for the dose – response relation in circulating 25OHD .