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Updated in 10/16/2022 6:37:55 PM      Viewed: 85 times      (Journal Article)
The American journal of clinical nutrition 99 (3): 587-98 (2014)

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
ABSTRACT
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.Our primary objective was to determine the dose-response relation between vitamin D and plasma 25(OH)D.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.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.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.
DOI: 10.3945/ajcn.113.067777      ISSN: 0002-9165