Rising serum 25-hydroxy-vitamin D levels after weight loss in obese women correlate with improvement in insulin resistance. Type of dietary fat is associated with the 25-hydroxyvitamin D3 increment in response to vitamin D supplementation. Large Doses of Vitamin D Fail to Increase 25-Hydroxyvitamin D Levels or to Alter Cardiovascular Risk Factors in Obese Adolescents: A Pilot Study. Three doses of vitamin D, bone mineral density, and geometry in older women during modest weight control in a 1-year randomized controlled trial Preliminary data about the influence of vitamin D status on the loss of body fat in young overweight/obese women following two types of hypocaloric diet. Effects of weight loss on serum vitamin D in postmenopausal women. Influence of Calcium and Vitamin D Supplementation on Weight and Fat Loss in Obese Women The Effect of High-Dose Vitamin D Supplementation on Calciotropic Hormones and Bone Mineral Density in Obese Subjects with Low Levels of Circulating 25-Hydroxyvitamin D: Results from a Randomized Controlled Study Vitamin D3 supplementation during weight loss: a double-blind randomized controlled trial. Dairy Foods in a Moderate Energy Restricted Diet Do Not Enhance Central Fat, Weight, and Intra-Abdominal Adipose Tissue Losses nor Reduce Adipocyte Size or Inflammatory Markers in Overweight and Obese Adults: A Controlled Feeding Study Prospective Study of Serum 25-hydroxy Vitamin D and Tooth Loss Supplementation with cholecalciferol does not result in weight reduction in overweight and obese subjects. Cross-sectional and longitudinal relation between serum 25-hydroxyvitamin D and body mass index: the Tromsø 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.
OBJECTIVE The objective of the study was to examine changes of 25-hydroxy-vitamin D ( 25OHD ) and PTH blood levels 4 and 20 wk after low-calorie diet-induced weight loss . METHODS Forty-four obese women [ aged 40.6 + /- 11.4 yr , body mass index ( BMI ) 36.7 + /- 4.9 kg/m(2 ) ] and 25 controls ( BMI 22.9 + /- 1.5 kg/m(2 ) ) were examined .  Anthropometric and cardiometabolic parameters and 25OHD and PTH levels  were determined at baseline and 4 and 20 wk after a low-calorie diet . RESULTS At baseline , 25OHD levels were lower in obese compared with control subjects ( 17 + /- 6.0 vs. 23.8 + /- 8.7 ng/ml , P < 0.001 ) , whereas no differences were found in PTH levels . In all women , a negative correlation was found between 25OHD levels and body weight ( BW ) ( r -0.32 , P < 0.001 ) , BMI ( r -0.37 , P < 0.001 ) , waist circumference ( r -0.26 , P < 0.05 ) , and percent fat mass ( r -0.38 , P = 0.001 ) as determined by bioelectrical impedance analysis . The 4-wk low-calorie diet ( n = 37 ) reduced BW and led to significant improvements in the homeostasis model assessment ( HOMA ) index and lipid levels . The 20-wk low-calorie diet ( n = 26 ) result ed in reduction of BW and BMI by 10 % , HOMA index ( 4.7 + /- 3.8 vs. 3.10 + /- 1.7 , P < 0.01 ) , and lipids levels ( except high density lipoprotein cholesterol ) and increase in 25OHD ( 15.4 + /- 6.0 vs. 18.3 + /- 5.1 ng/ml , P < 0.05 ) , compared with baseline . PTH levels were unchanged . The increase of 25OHD levels was associated with the reduction of insulin levels and HOMA index ( r -0.43 , P < 0.05 ) . CONCLUSIONS Blood 25OHD levels were low in obese women and correlated inversely with severity measures of obesity . Weight loss of 10 % after low-calorie diet increased 25OHD levels , and this increase was mainly associated with improvement of insulin resistance CONTEXT Mono- and polyunsaturated fats may have opposing effects on vitamin D absorption . OBJECTIVE The purpose of this study was to determine whether intakes of different dietary fats are associated with the increase in serum 25-hydroxyvitamin D ( 25OHD ) after supplementation with vitamin D(3 ) . DESIGN , SETTING , AND PARTICIPANTS This analysis was conducted in the active treatment arm of a r and omized , double-blind , placebo-controlled trial of vitamin D and calcium supplementation to prevent bone loss and fracture . Subjects included 152 healthy men and women age 65 and older who were assigned to 700 IU/d vitamin D(3 ) and 500 mg/d calcium .  Intakes of monounsaturated fatty acids ( MUFA ) , polyunsaturated fatty acids ( PUFA ) , and saturated fatty acids ( SFA ) were estimated by food frequency question naire . MAIN OUTCOME MEASURE The change in plasma 25OHD during 2 yr  vitamin D and calcium supplementation was assessed . RESULTS The change in plasma 25OHD ( nanograms per milliliter ) during vitamin D supplementation was positively associated with MUFA , ( β = 0.94 ; P = 0.016 ) , negatively associated with PUFA , ( β = -0.93 ; P = 0.038 ) , and positively associated with the MUFA/PUFA ratio ( β = 6.46 ; P = 0.014 ) . CONCLUSION The fat composition of the diet may influence the 25OHD response to supplemental vitamin D(3 ) . Diets rich in MUFA may improve and those rich in PUFA may reduce the effectiveness of vitamin D(3 ) supplements in healthy older adults . More studies are needed to confirm these findings 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 Summary The effects of higher than recommended vitamin D doses on bone mineral density ( BMD ) and quality are not known . In this study , higher intakes , in postmenopausal women undergoing weight control over 1 year , had no effect on areal or volumetric BMD but prevented the deterioration in cortical bone geometry . Introduction Studies examining how bone responds to a st and ard dose of vitamin D supplementation have been inconsistent . In addition , the effects of higher doses on BMD and quality are not known . Postmenopausal women undergoing weight control to improve health outcomes are particularly at risk for bone loss and might benefit from supplemental vitamin D intake above the recommended allowance . Methods This 1-year-long , r and omized , double-blind controlled study addresses whether vitamin D supplementation , in healthy overweight/obese older women , affects BMD and bone structural parameters . In addition , bone turnover and serum total , free , and bioavailable 25-hydroxyvitamin D ( 25OHD ) responses to one of three daily levels of vitamin D3 ( 600 , 2000 , 4000 IU ) with 1.2 Ca g/day during weight control were examined . Results Fifty-eight women ( age , 58 ± 6 years ; body mass index , 30.2 ± 3.8 kg/m2 , serum 25OHD , 27.3 ± 4.4 ng/mL ) were r and omized to treatment . After 1 year , serum 25OHD concentrations increased to 26.5 ± 4.4 , 35.9 ± 4.5 , and 41.5 ± 6.9 ng/mL , in groups 600 , 2000 , and 4000 IU , respectively , and differed between groups ( p < 0.01 ) . Weight change was similar between groups ( −3.0 ± 4.1 % ) . Cortical ( Ct ) thickness of the tibia changed by −1.5 ± 5.1 % , + 0.6 ± 3.2 % , and + 2.0 ± 4.5 % in groups 600 , 2000 , and 4000 IU , respectively , and each group was significantly different from each other ( p < 0.05 ) . Conclusion The decline in Ct thickness was prevented with higher vitamin D3 supplementation , but there were no other significant changes due to treatment over 1 year . Whether these findings translate to changes in biomechanical properties leading to reduced fracture risk should be addressed in future studies The loss of weight was analysed in a group of sixty overweight/obese women of childbearing age ( 20 - 35 years ) according to their initial vitamin D status . Subjects were r and omly assigned to one of two slightly hypocaloric diets : Diet V , in which the consumption of vegetables was increased , or Diet C , in which the relative consumption of cereals ( especially breakfast cereals ) was increased .  Dietetic , anthropometric and biochemical data were collected at the start of the study and again at 2 weeks after dividing the women into groups depending on their having an initial serum 25-hydroxyvitamin D ( 25(OH)D ) concentration of < 50 nmol/l ( LD ) or > or=50 nmol/l ( HD ) . Dietary intervention led to a reduction in energy intake , body weight and BMI in all groups . The HD women showed greater body fat losses during the study than the LD women ( 1.7 ( SD 1.8 ) kg compared to 0.5 ( SD 0.8 ) kg ) . A better vitamin D status therefore aided the loss of body fat over the experimental period ( OR 0.462 ; CI 0.271 , 0.785 ; P < 0.001 ) . However , when the dietary groups were analysed separately , this effect was only seen in the C subjects ( OR 0.300 ; CI 0.121 , 0.748 ; P < 0.001 ) . The present results suggest that women with a better vitamin D status respond more positively to  hypocaloric diets  and lose more body fat ; this was especially clear among the C subjects who had a greater vitamin D supply during the experimental period BACKGROUND Low concentrations of circulating vitamin D are common with obesity and may represent a potential mechanism explaining the elevated risk of certain cancers and cardiovascular outcomes observed in individuals who are overweight or obese . OBJECTIVE The objective of this study was to investigate the effects of 12 mo of weight loss through caloric restriction , exercise intervention , or both on serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations . DESIGN Overweight and obese postmenopausal women ( n = 439 ) were r and omly assigned to 1 of 4 groups : 1 ) diet modification ( n = 118 ) , 2 ) exercise ( n = 117 ) , 3 ) diet + exercise ( n = 117 ) , or 4 ) control ( n = 87 ) . The diet intervention was a group-based reduced-calorie program with a 10 % weight-loss goal . The exercise intervention consisted of 45 min of moderate-to-vigorous intensity aerobic activity daily for 5 d/wk . Serum 25(OH)D concentrations were measured by using a competitive chemiluminescent immunoassay at baseline and 12 mo . RESULTS No significant change in serum 25(OH)D was found between the intervention and control groups . Women who lost < 5 % , 5 - 9.9 % , 10 - 14.9 % , or ≥15 % of baseline weight had mean increases in 25(OH)D of 2.1 , 2.7 , 3.3 , and 7.7 ng/mL , respectively ( P for trend = 0.002 ) . Baseline vitamin D status did not modify the effect of the interventions on weight loss or body-composition changes at the 12-mo follow-up . CONCLUSION A greater degree of weight loss , achieved through either a reduced-calorie diet or increased exercise , is associated with increased circulating 25(OH)D concentrations . This trial is registered at clinical trials.gov as NCT00470119 Background : Dairy products not only reduce the risk of hypertension and cardiovascular diseases but may play a role in the treatment of obesity . As there is some evidence that calcium ( Ca ) and vitamin D may play a role in effective weight management , we decided to evaluate the influence of Ca and vitamin D supplementation on weight and fat loss  in obese women . Material and Methods : Forty obese women were enrolled in this study . Subjects were divided into 2 groups comparable with body mass index ( BMI ) and age . Group 1 was provided with calcium carbonate and 1-(OH)-vitamin D supplementation . Group 2 was provided with only a diet . Subjects participated in a 3-month weight reduction therapy ( balanced diet , modification of life style , and regular physical exercise ) . Blood sample s ( serum concentration of Ca , phosphorus ( P ) , parathormone ( PTH ) , 25-(OH)-D3 ) and clinical characteristics ( weight , height , BMI , body composition ) were taken at baseline and after the 3-month program . Results : No significant differences of body weight , body fat content , serum parathormone , 25-(OH)-D3 concentration , and plasma total Ca and P concentration were observed between analyzed groups both before and after the treatment . Additionally , we did not observe any significant influence of Ca and vitamin D supplementation on weight and fat loss . Conclusion : Ca plus vitamin D supplementation during a 3-month low caloric diet has no additional effect on weight and fat loss in obese women Low levels of 25-hydroxyvitamin D ( 25OHD ) are associated with increased bone turnover and risk of fractures . Plasma 25OHD is inversely related to body mass index , and vitamin D deficiency is common in obesity . We aim ed to determine whether vitamin D supplementation affects bone turnover and bone mineral density ( BMD ) in obese subjects . Fifty-two healthy obese men and women aged 18–50 years with plasma 25OHD levels below 50 nmol/L were r and omized to 7,000 IU of cholecalciferol daily or placebo for 26 weeks . We measured plasma levels of 25OHD , parathyroid hormone ( PTH ) , and markers of bone turnover , as well as BMD at the hip , spine , forearm , and whole body . Compared with placebo , treatment with cholecalciferol  increased mean plasma 25OHD from 35 to 110 nmol/L ( p < 0.00001 ) and significantly decreased PTH ( p < 0.05 ) . BMD increased significantly at the forearm by 1.6 ± 0.7 % ( p = 0.03 ) . The bone resorption marker C-terminal telopetide of type 1 collagen ( CTX ) decreased borderline significantly in the cholecalciferol group compared with the placebo group ( p = 0.07 ) . Changes in plasma 25OHD correlated inversely with changes in plasma levels of bone-specific alkaline phosphatase ( r = −0.38 , p = 0.01 ) and CTX ( r = −0.33 , p = 0.03 ) . Changes in CTX correlated inversely with changes in spine BMD ( r = −0.45 , p = 0.04 ) . Increasing circulating 25OHD levels by cholecalciferol treatment is of importance to bone health in young obese subjects as increased levels of 25OHD are associated with a decrease in both PTH and bone turnover and with an increase in BMD at the forearm BACKGROUND Vitamin D deficiency is associated with obesity ; whether repletion supports weight loss and changes obesity-related biomarkers is unknown . OBJECTIVE We compared 12 mo of vitamin D3 supplementation with placebo  on weight , body composition , insulin , and C-reactive protein ( CRP ) in postmenopausal women in a weight-loss intervention . DESIGN A total of 218 overweight/obese women ( 50 - 75 y of age ) with serum 25-hydroxyvitamin D [ 25(OH)D ] ≥10 ng/mL but < 32 ng/mL were r and omly assigned to weight loss + 2000 IU oral vitamin D3/d or weight loss + daily placebo . The weight-loss intervention included a reduced-calorie diet ( 10 % weight loss goal ) and 225 min/wk of moderate-to-vigorous aerobic activity . Mean 12-mo changes in weight , body composition , serum insulin , CRP , and 25(OH)D were compared between groups ( intent-to-treat ) by using generalized estimating equations . RESULTS A total of 86 % of participants completed the 12-mo measurements . The mean ( 95 % CI ) change in 25(OH)D was 13.6 ( 11.6 , 15.4 ) ng/mL in the vitamin D3 arm compared with -1.3 ( -2.6 , -0.3 ) ng/mL in the placebo arm ( P < 0.0001 ) . Changes in weight [ -7.1 ( -8.7 , -5.7 ) compared with -7.4 ( -8.1 , -5.4 ) kg ] , body mass index ( in kg/m(2 ) : both -2.8 ) , waist circumference [ -4.9 ( -6.7 , -2.9 ) compared with -4.5 ( -5.6 , -2.6 ) cm ] , percentage body fat [ -4.1 ( -4.9 , -2.9 ) compared with -3.5 ( -4.5 , -2.5 ) ] , trunk fat [ -4.1 ( -4.7 , -3.0 ) compared with -3.7 ( -4.3 , -2.9 ) kg ] , insulin [ -2.5 ( -3.4 , -1.7 ) compared with -2.4 ( -3.3 , -1.4 ) μU/mL ] , and CRP [ -0.9 ( -1.2 , -0.6 ) compared with -0.79 ( -0.9 , -0.4 ) mg/L ] [ corrected ] were similar between groups ( all P > 0.05 ) . Compared with women who achieved 25(OH)D < 32 ng/mL , women r and omly assigned to vitamin D who became replete ( ie , 25(OH)D ≥32 ng/mL ) lost more weight [ -8.8 ( -11.1 , -6.9 ) compared with -5.6 ( -7.2 , -5.0 ) kg ; P = 0.05 ] , waist circumference [ -6.6 ( -9.3 , -4.3 ) compared with -2.5 ( -4.6 , -2.0 ) cm ; P = 0.02 ] , and percentage body fat [ -4.7 ( -6.1 , -3.5 ) compared with -2.6 ( -3.9 , -2.2 ) ; P = 0.04 ] . Among women with complete pill counts ( 97 % adherence ) , the mean decrease in CRP was 1.18 mg/mL ( 46 % ) in the vitamin D arm compared with 0.46 mg/mL ( 25 % ) in the placebo arm ( P = 0.03 ) . CONCLUSIONS Vitamin D3 supplementation  during weight loss did not increase weight loss or associated factors compared with placebo ; however , women who became replete experienced greater improvements . This trial was registered at clinical trials.gov as NCT01240213 Background . Research on dairy foods to enhance weight and fat loss when incorporated into a modest weight loss diet has had mixed results . Objective . A 15-week controlled feeding study to determine if dairy foods enhance central fat and weight loss when incorporated in a modest energy restricted diet of overweight and obese adults . Design . A 3-week run-in to establish energy needs ; a 12-week 500 kcal/d energy reduction with 71 low-dairy-consuming overweight and obese adults r and omly assigned to diets : ≤1 serving dairy/d ( low dairy , LD ) or ≤4 servings dairy/d ( adequate dairy , AD ) . All foods were weighed and provided by the metabolic kitchen . Weight , fat , intra-abdominal adipose tissue ( IAAT ) , subcutaneous adipose tissue ( SAT ) macrophage number , SAT inflammatory gene expression , and circulating cytokines were measured . Results . No diet differences were observed in weight , fat , or IAAT loss ; nor SAT mRNA expression of inflammation , circulating cytokines , fasting lipids , glucose , or insulin . There was a significant increase ( P = 0.02 ) in serum 25-hydroxyvitamin D in the AD group . Conclusion . Whether increased dairy intake during weight loss results in greater weight and fat loss for individuals with metabolic syndrome deserves investigation . Assessment of appetite , hunger , and satiety with followup on weight regain should be considered Vitamin  D deficiency and oral diseases ( periodontitis , caries , and tooth loss ) are highly prevalent in Germany . Previous studies suggested that vitamin D might be a modifiable and protective factor for periodontitis , caries , and tooth loss . However , prospect i ve studies investigating such associations are limited . We explored the association between the concentration of  serum 25-hydroxy vitamin D ( 25OHD ) and incidence of tooth loss , progression of clinical attachment loss ( CAL ) ≥ 3 mm , and progression of restorative and caries status in a population -based longitudinal study . We analyzed data from 1,904 participants from the Study of Health in Pomerania with a five-year follow-up . Generalized estimating equation models were applied to evaluate tooth-specific associations between serum 25OHD and incidence of tooth loss , progression of CAL ≥ 3 mm , and progression of restorative and caries status . Age , sex , education , smoking status , alcohol drinking , waist circumference , dental visit frequency , reasons of dental visit , vitamin D or calcium supplements , and season of blood draw were considered as confounders . Serum 25OHD was inversely associated with incidence of tooth loss . A significant dose-response relationship ( p = .0022 ) was observed across the quintiles of serum 25OHD . After adjusting for multiple confounders , each 10-µg/L increase of serum 25OHD was associated with a 13 % decreased risk of tooth loss ( risk ratio : 0.87 ; 95 % confidence interval : 0.79 , 0.96 ) . The association was attenuated for changes of CAL ≥ 3 mm when adjusting for multiple confounders . No significant association was found between serum 25OHD and caries progression  . Vitamin D might be a protective factor for tooth loss . The effect might partially be mediated by its effect on periodontitis OBJECTIVE Investigate whether cholecalciferol supplementation leads to weight loss in overweight and obese adults . DESIGN R and omized double blind clinical trial with 20,000 IU cholecalciferol twice a week , or 20,000 IU once a week plus placebo , or placebo twice a week , for 12 months . All subjects were given 500 mg calcium supplementation . METHODS Four hundred and forty five healthy , overweight , and obese men and women ( age 21 - 70 years , body mass index ( BMI ) 28.0 - 47.0 kg/m(2 ) ) .  Body weight , fatness , and fat distribution parameters were measured by dual-energy X-ray absorptiometry and anthropometry , blood sample s and 24-h urinary sample s were collected . RESULTS At baseline , there were no significant differences between the groups , but there was a significant inverse relation between serum 25-hydroxyvitamin D ( 25(OH)D ) levels and BMI , and a significant positive association between calorie intake and BMI .  Three hundred and thirty four subjects completed the study . During the study , there was no significant change in weight , waist-to-hip ratio ( WHR ) or percentage body fat in any of the groups , nor between them . Parathyroid hormone decreased and 25(OH)D increased significantly in both groups receiving cholecalciferol , and serum levels of 25(OH)D stabilized after 3 months . Serum calcium was unchanged in all groups . Urinary calcium excretion increased in all groups , but there was no significant difference between the groups . Weekly dosage of 20,000 - 40,000 IU cholecalciferol for 12 months was associated with a low risk of adverse effects , at least in overweight and obese adults living at latitude 70 degrees N. CONCLUSION Significant weight reduction in overweight and obese subjects is unlikely to occur with cholecalciferol supplementation 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 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
Collectively , these outcomes support a volumetric dilution of vitamin D. The slopes of the respective regression lines , however , indicate a smaller increase in 25OHD than would be expected from a direct mobilization of stores into the circulation .
Hence , sequestration of 25OHD and its conversion to inactive metabolites would also play a role .
The purpose of this review was to confirm a volumetric dilution of vitamin D in obesity .
It was based on the hypothesis that weight loss , particularly fat loss , would increase serum 25-hydroxyvitamin D ( 25OHD ) in the obese .