Dataset Information

Dose response to vitamin D supplementation in African Americans: results of a 4-arm, randomized, placebo-controlled trial.

ABSTRACT:

Background

Association studies have suggested that lower circulating 25-hydroxyvitamin D [25(OH)D] in African Americans may partially underlie higher rates of cardiovascular disease and cancer in this population. Nonetheless, the relation between vitamin D supplementation and 25(OH)D concentrations in African Americans remains undefined.

Objective

Our primary objective was to determine the dose-response relation between vitamin D and plasma 25(OH)D.

Design

A total of 328 African Americans in Boston, MA, were enrolled over 3 winters from 2007 to 2010 and randomly assigned to receive a placebo or 1000, 2000, or 4000 IU vitamin D₃/d for 3 mo. Subjects completed sociodemographic and dietary questionnaires, and plasma samples were drawn at baseline and 3 and 6 mo.

Results

Median plasma 25(OH)D concentrations at baseline were 15.1, 16.2, 13.9, and 15.7 ng/mL for subjects randomly assigned to receive the placebo or 1000, 2000, or 4000 IU/d, respectively (P = 0.63). The median plasma 25(OH)D concentration at 3 mo differed significantly between supplementation arms at 13.7, 29.7, 34.8, and 45.9 ng/mL, respectively (P < 0.001). An estimated 1640 IU vitamin D₃/d was needed to raise the plasma 25(OH)D concentration to ≥ 20 ng/mL in ≥ 97.5% of participants, whereas a dose of 4000 IU/d was needed to achieve concentrations ≥ 33 ng/mL in ≥ 80% of subjects. No significant hypercalcemia was seen in a subset of participants.

Conclusions

Within African Americans, an estimated 1640 IU vitamin D₃/d was required to achieve concentrations of plasma 25(OH)D recommended by the Institute of Medicine, whereas 4000 IU/d was needed to reach concentrations predicted to reduce cancer and cardiovascular disease risk in prospective observational studies. These results may be helpful for informing future trials of disease prevention.

SUBMITTER: Ng K

PROVIDER: S-EPMC3927692 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Publications

Dose response to vitamin D supplementation in African Americans: results of a 4-arm, randomized, placebo-controlled trial.

Ng Kimmie K Scott Jamil B JB Drake Bettina F BF Chan Andrew T AT Hollis Bruce W BW Chandler Paulette D PD Bennett Gary G GG Giovannucci Edward L EL Gonzalez-Suarez Elizabeth E Meyerhardt Jeffrey A JA Emmons Karen M KM Fuchs Charles S CS

The American journal of clinical nutrition 20131224 3

<h4>Background</h4>Association studies have suggested that lower circulating 25-hydroxyvitamin D [25(OH)D] in African Americans may partially underlie higher rates of cardiovascular disease and cancer in this population. Nonetheless, the relation between vitamin D supplementation and 25(OH)D concentrations in African Americans remains undefined.<h4>Objective</h4>Our primary objective was to determine the dose-response relation between vitamin D and plasma 25(OH)D.<h4>Design</h4>A total of 328 Af ...[more]

PMID: 24368437

Similar Datasets

Project description:BackgroundA critical need exists to better understand the physiological sequel of vitamin D supplementation in obese individuals and African Americans. The aim was to comprehensively evaluate dose- and time-responses of a panel of vitamin D biomarkers to vitamin D supplements in this population.MethodsWe conducted a 16-week randomized, double-blinded, and placebo-controlled clinical trial. Seventy overweight/obese African Americans (age 13-45 years, 84 % females) with 25-hydroxyvitamin D [25(OH)D] concentrations ≤20 ng/mL were randomly assigned to receive a supervised monthly oral vitamin D3 of 18,000 IU (~600 IU/day, n = 17), 60,000 IU (~2000 IU/day, n = 18), 120,000 IU (~4000 IU/day, n = 18), or placebo (n = 17).ResultsThere were significant dose- and time-responses of circulating 25(OH)D, 1,25-dihydroxyvitamin D [1,25(OH)2D], and intact parathyroid hormone (iPTH), but not fibroblast growth factor-23 (FGF-23), phosphorus and urine calcium to the vitamin D supplements. The mean 25(OH)D concentrations in the 2000 IU and 4000 IU groups reached ≥30 ng/mL as early as 8-weeks and remained at similar level at 16-weeks. The increase of 25(OH)D was significantly higher in the 4000 IU group than all the other groups at 8-weeks. The increase of 1,25(OH)2D was significantly higher in the 2000 IU and 4000 IU groups than the placebo at 8-weeks. Only the 4000 IU compared to the placebo significantly reduced iPTH at 8- and 16-weeks.ConclusionsOur RCT, for the first time, comprehensively evaluated time- and dose- responses of vitamin D supplementation in overweight/obese African Americans with suboptimal vitamin D status. Circulating 25(OH)D, 1,25(OH)2D, and iPTH, but not FGF-23, phosphorus and urine calcium, respond to vitamin D supplementation in a time- and dose-response manner. By monthly dosing, 2000 IU appears to be sufficient in achieving a 25(OH)D level of 30 ng/mL in this population. However, importantly, 4000 IU, rather than 2000 IU, seems to suppress iPTH. If replicated, these data might be informative in optimizing vitamin D status and providing individualized dosing recommendation in overweight/obese African Americans.Trial registrationClinicalTrials.gov number: NCT01583621, Registered on April 3, 2012.

Project description:BACKGROUND:Antenatal vitamin D status may be associated with the risk of adverse pregnancy and neonatal outcomes; however, the benefits of vitamin D supplementation during pregnancy remain unknown. METHODS:We conducted a double-blind placebo-controlled randomized trial to evaluate the effect of high-dose prenatal 3rd trimester vitamin D3 supplementation on maternal and neonatal (cord blood) serum 25-hydroxyvitamin D (25(OH)D) concentration (primary biochemical efficacy outcome) and maternal serum calcium concentration (primary safety measure). Eligibility criteria were pregnant women aged 18 to <35 years, at 26 to 29 weeks gestation, and residing in Dhaka, Bangladesh. 160 women were randomized by 1:1 allocation to one of two parallel intervention groups; placebo (n?=?80) or 35,000 IU/week of vitamin D3 (n?=?80) until delivery. All participants, study personnel and study investigators were blind to treatment allocation. RESULTS:Mean maternal 25(OH)D concentration was similar in the vitamin D and placebo groups at baseline (45 vs. 44 nmol/L; p?=?0.66), but was significantly higher in the vitamin D group vs. placebo group among mothers at delivery (134 vs. 38 nmol/L; p?<?0.001) and newborns (cord blood: 103 vs. 39; p?<?0.001). In the vitamin D group, 95% of neonates and 100% of mothers attained 25(OH)D?>50 nmol/L, versus 21% mothers and 19% of neonates in the placebo group. No participants met criteria for hypercalcemia, there were no known supplement-related adverse events, and major pregnancy outcomes were similar between groups. CONCLUSIONS:Antenatal 3rd-trimester vitamin D3 supplementation (35,000 IU/week) significantly raised maternal and cord serum 25(OH)D concentrations above 50 nmol/L in almost all participants without inducing hypercalcemia or other observed safety concerns. Doses up to 35,000 IU/week may be cautiously used in further research aimed at establishing the clinical effects and safety of vitamin D3 supplementation in pregnancy. TRIAL REGISTRATION:This trial was registered at ClinicalTrials.gov (NCT01126528).

Dataset Information

Dose response to vitamin D supplementation in African Americans: results of a 4-arm, randomized, placebo-controlled trial.

Background

Objective

Design

Results

Conclusions

Publications

Dose response to vitamin D supplementation in African Americans: results of a 4-arm, randomized, placebo-controlled trial.

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