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

Kimmie Ng, Jamil B. Scott, Bettina F. Drake, Andrew T. Chan, Bruce W. Hollis, Paulette D. Chandler, Gary G. Bennett, Edward L. Giovannucci, Elizabeth Gonzalez-Suarez, Jeffrey A. Meyerhardt, Karen M. Emmons, Charles S. Fuchs

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

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 doseresponse 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 cardio-vascular disease risk in prospective observational studies. These results may be helpful for informing future trials of disease prevention. This trial was registered at clinicaltrials.gov as NCT00585637.

Original languageEnglish
Pages (from-to)587-598
Number of pages12
JournalAmerican Journal of Clinical Nutrition
Volume99
Issue number3
DOIs
StatePublished - 1 Mar 2014
Externally publishedYes

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