Dataset Information

Effects of vitamin D binding protein phenotypes and vitamin D supplementation on serum total 25(OH)D and directly measured free 25(OH)D.

ABSTRACT: OBJECTIVE:To determine the relationship between serum total 25-hydroxyvitamin D (25(OH)D), directly measured free 25(OH)D and calculated free 25(OH)D with regard to vitamin D-binding protein (DBP) phenotypes, sex, BMI, age and season, and their interrelationship to vitamin D supplementation. DESIGN, PATIENTS AND INTERVENTIONS:A randomized controlled trial with 20?000?IU of vitamin D3 per week or placebo for 12 months was designed. A total of 472 subjects, 236 in each of the intervention groups, were included in the analyses. MAIN OUTCOME MEASURES:Baseline serum concentrations and increases in serum total 25(OH)D, directly measured free 25(OH)D, calculated free 25(OH)D and DBP. RESULTS:Serum total 25(OH)D and DBP concentrations were significantly lower in subjects with the phenotype Gc2/Gc2 compared to phenotypes with the Gc1S allele, and lower in males compared to females. When using directly measured free 25(OH)D, the differences related to DBP phenotypes and sexes were clearly diminished. All calculated free 25(OH)D concentrations were overestimated compared to the directly measured free 25(OH)D. Serum parathyroid hormone showed an inverse correlation with all vitamin D parameters analyzed. The increases after 12 months of vitamin D supplementation were not significantly different for any of the vitamin D parameters regardless of DBP phenotype, sex or age. Supplementation with vitamin D did not affect serum DBP. CONCLUSION:Direct measurements of free 25(OH)D reduce the differences seen in total 25(OH)D between DBP phenotype groups and sexes, probably caused by differences in DBP concentrations. With conditions affecting serum DBP concentrations, direct measurements of free 25(OH)D should be considered.

SUBMITTER: Sollid ST

PROVIDER: S-EPMC4763092 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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Effects of vitamin D binding protein phenotypes and vitamin D supplementation on serum total 25(OH)D and directly measured free 25(OH)D.

Sollid Stina T ST Hutchinson Moira Y S MY Berg Vivian V Fuskevåg Ole M OM Figenschau Yngve Y Thorsby Per M PM Jorde Rolf R

European journal of endocrinology 20160105 4

<h4>Objective</h4>To determine the relationship between serum total 25-hydroxyvitamin D (25(OH)D), directly measured free 25(OH)D and calculated free 25(OH)D with regard to vitamin D-binding protein (DBP) phenotypes, sex, BMI, age and season, and their interrelationship to vitamin D supplementation.<h4>Design, patients and interventions</h4>A randomized controlled trial with 20 000 IU of vitamin D3 per week or placebo for 12 months was designed. A total of 472 subjects, 236 in each of the interv ...[more]

PMID: 26733479

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Project description:BACKGROUND:The beneficial adaptation of skeletal muscle function to strenuous exercise is partially attributable to the improvement of vitamin D status. The present study aimed to evaluate the effects of a 3-week vitamin D supplementation on serum 25(OH)D levels and skeletal muscle biomarkers (i.e. troponin, myoglobin, creatine kinase and lactic dehydrogenase) of endurance runners. METHODS:A double-blind placebo-controlled study design was used and vitamin D supplementation was compared to a non-treatment control group. Twenty-four runners, competitors of the ultra-marathons held during the National Running Championships, were randomly assigned into two groups supplemented with the dose of 2000?IU vitamin D or placebo for three weeks. All subjects participated in three exercise protocols: (a) incremental exercise test (to determine the maximum oxygen uptake and the intensity of eccentric exercise), (b) eccentric exercise before and (c) after two dietary protocols. Venous blood samples were drawn at rest, immediately after the exercise and after 1?h and 24?h of recovery in order to estimate serum 25(OH)D levels, skeletal muscle biomarkers, proinflammatory cytokines and tumor necrosis factor-alpha (TNF-?) levels. A two-way ANOVA was used to test main effects and their interactions and Pearson correlation coefficients were analyzed to determine the effects of inter-variable relationships. RESULTS:Significant differences between pre- and post-intervention in baseline 25(OH)D levels were observed (34.9?±?4.7 versus 40.3?±?4.9?ng/ml, p?= 0.02) in supplemented group. A higher post intervention 25(OH)D level was observed after vitamin D diet compared to placebo (40.3?±?4.9 versus 31.8?±?4.2?ng/mL, respectively; p?< 0.05). The vitamin D supplementation decreased post-exercise (TN max) and 1?h post-exercise troponin (p?= 0.004, p?=?0.03, respectively), 1?h post-exercise myoglobin concentration (p?=?0.01) and TNF-? levels(p?<?0.03). 24?h post exercise creatine kinase activity was significantly lower in supplemented group compared to placebo (p?<?0.05). A negative correlation was observed between post exercise 25(OH)D levels and myoglobin levels (r?=?-?0.57; p?=?0.05), and 25(OH)D levels and TNF? (r?=?-?0.58; p?=?0.05) in vitamin D supplemented group. CONCLUSIONS:Three weeks of vitamin D supplementation had a positive effect on serum 25(OH)D levels in endurance trained runners and it caused a marked decrease in post-exercise biomarkers levels. We concluded that vitamin D supplementation might play an important role in prevention of skeletal muscle injuries following exercise with eccentric muscle contraction in athletes.

Project description:Background: Cardiovascular disease (CVD) risk factors are associated with low serum 25 hydroxyvitamin D (25(OH)D) concentrations in observational studies; however, clinical trial findings are inconsistent. Objective: We assessed the effect of vitamin D supplementation and increased serum 25(OH)D concentrations on CVD risk factors in a systemic review and meta-analysis of randomized controlled trials (RCTs). Design: MEDLINE, CINAHL, EMBASE, and Google Scholar were searched for RCTs that evaluated vitamin D supplementation and cardiovascular outcomes [blood pressure, parathyroid hormone (PTH), serum high-sensitivity C-reactive protein (hs-CRP), total cholesterol, high and low density lipoprotein (HDL and LDL, respectively), triglycerides, peak wave velocity (PWV) and Augmentation Index (AI)] from 1992 through 2017. Meta-analysis was based on a random-effects model and inverse variance method to calculate standardized mean difference (SMD) as effect sizes, followed by a leave-one-out method for sensitivity analysis. Risk of publication bias was assessed using Cochrane checklist and Begg funnel plots. The systematic review is registered as CRD42015025346. Results: We identified 2341 studies from which 81 met inclusion criteria. The meta-analysis indicated a significant reduction in systolic blood pressure (SMD = -0.102 ± 0.04 mmHg, 95% confidence interval (CI), -0.20 to -0.03), diastolic blood pressure (SMD = -0.07 ± 0.03 mmHg, 95% CI, -0.14 to -0.006), serum PTH (SMD = -0.66 ± 0.08 ng/L, 95% CI, -0.82 to -0.49), hs-CRP (SMD = -0.20 ± 0.07 mg/L, 95% CI, -0.34 to -0.06), total cholesterol (SMD = -0.15 ± 0.06 mmol/L, 95% CI, -0.25 to -0.04), LDL (SMD = -0.10 ± 0.05 mmol/L, 95% CI, -0.20 to -0.003), triglycerides (SMD = -0.12 ± 0.06 mmol/L, 95% CI, -0.23 to -0.003) and a significant increase in HDL (SMD = 0.09 ± 0.04 mmol/L, 95% CI, 0.00 to 0.17) with vitamin D supplementation. These findings remained significant in sensitivity analyses for blood pressure, lipid profile, serum PTH, and serum hs-CRP. There was no significant effect of vitamin D supplementation on PWV (SMD = -0.20 ± 0.13 m/s, 95% CI, -0.46 to 0.06, p = 0.14) and AI (SMD = -0.09 ± 0.14%, 95% CI, -0.37 to 0.19, p = 0.52) for vitamin D supplemented groups. Conclusion: These findings suggest that vitamin D supplementation may act to protect against CVD through improving risk factors, including high blood pressure, elevated PTH, dyslipidemia, and inflammation.

Project description:ContextThe optimal measure of vitamin D status is unknown.ObjectiveTo directly measure circulating free 25-hydroxyvitamin D [25(OH)D] concentrations and relationships to total 25(OH)D in a clinically diverse sample of humans.DesignCross-sectional analysis.SettingSeven academic sites.PatientsA total of 1661 adults: healthy (n = 279), prediabetic (n = 479), outpatients (n = 714), cirrhotic (n = 90), pregnant (n = 20), nursing home resident (n = 79).InterventionsMerge research data on circulating free 25(OH)D (directly-measured immunoassay), total 25(OH)D (liquid chromatography/tandem mass spectrometry), D-binding protein [DBP; by radial (polyclonal) immunodiffusion assay], albumin, creatinine, intact parathyroid hormone, and DBP haplotype.Main outcome measuresDistribution of free 25(OH)D (ANOVA with Bonferroni correction for post hoc comparisons) and relationships between free and total 25(OH)D (mixed-effects modeling incorporating clinical condition, DBP haplotype with sex, race, estimated glomerular filtration rate (eGFR), body mass index (BMI), and other covariates).ResultsFree 25(OH)D was 4.7 ± 1.8 pg/mL (mean ± SD) in healthy persons and 4.3 ± 1.9 pg/mL in outpatients, with levels of 0.5 to 8.1 pg/mL and 0.9 to 8.1 pg/mL encompassing 95% of healthy persons and outpatients, respectively. Free 25(OH)D was higher in patients with cirrhosis (7.1 ± 3.0 pg/mL; P < 0.0033) and nursing home residents (7.9 ± 2.1 pg/mL; P < 0.0033) than in other groups and differed between whites and blacks (P < 0.0033) and between DBP haplotypes (P < 0.0001). Mixed-effects modeling of relationships between free and total 25(OH)D identified clinical conditions (patients with cirrhosis > nursing home residents > patients with prediabetes > outpatients > pregnant women) and BMI (lesser effect) as covariates affecting relationships but not eGFR, sex, race, or DBP haplotype.ConclusionsTotal 25(OH)D, health condition, race, and DBP haplotype affected free 25(OH)D, but only health conditions and BMI affected relationships between total and free 25(OH)D. Clinical importance of free 25(OH)D needs to be established in studies assessing outcomes.

Dataset Information

Effects of vitamin D binding protein phenotypes and vitamin D supplementation on serum total 25(OH)D and directly measured free 25(OH)D.

Publications

Effects of vitamin D binding protein phenotypes and vitamin D supplementation on serum total 25(OH)D and directly measured free 25(OH)D.

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