(22-08-10) A 16-Week Randomized Clinical Trial of 2000 International Units Daily Vitamin D3 Supplementation in Black Youth: 25-Hydroxyvitamin D

Dong Y, Stallmann-Jorgensen IS, Pollock NK, Harris RA, Keeton D, Huang Y, Li K, Bassali R, Guo DH, Thomas J, Pierce GL, White J, Holick MF, Zhu H.
Georgia Prevention Institute, Department of Pediatrics (Y.D., I.S.S.-J., N.K.P., R.A.H., D.K., Y.H., K.L., D.G., J.T., G.L.P., H.Z.); General Pediatrics, Department of Pediatrics (R.B.), and Endocrinology, Department of Medicine (J.W.), Medical College of Georgia, Augusta, Georgia 30912; and Endocrinology, Department of Medicine (M.F.H.), Boston University Medical Center, School of Medicine, Boston, Massachusetts 02118.
Abstract
Context: Vitamin D insufficiency/deficiency is commonly observed in black youth. Objective: The aim was to determine 25-hydroxyvitamin D [25(OH)D] in response to 2000 IU vitamin D supplementation over time; to evaluate the relation between 25(OH)D concentrations and total body fat mass by dual-energy x-ray absorptiometry; and to determine whether vitamin D supplementation improves arterial stiffness measured by pulse wave velocity (PWV). Design: We conducted a randomized, blinded, controlled clinical trial. Setting and Participants: Forty-nine normotensive black boys and girls, aged 16.3 +/- 1.4 yr, were randomly assigned to either the control group (400 IU/d; n = 24) or the experimental group (2000 IU/d; n = 25). Results: Plasma 25(OH)D values at baseline and at 4, 8, and 16 wk were 34.0 +/- 10.6, 44.9 +/- 9.4, 51.2 +/- 11.1, and 59.8 +/- 18.2 nmol/liter, respectively, for the control group; and 33.1 +/- 8.7, 55.0 +/- 11.8, 70.9 +/- 22.0, and 85.7 +/- 30.1 nmol/liter, respectively, for the experimental group. The experimental group vs. the control group reached significantly higher 25(OH)D concentrations at 8 and 16 wk, respectively. Partial correlation analyses indicated that total body fat mass at baseline was significantly and inversely associated with 25(OH)D concentrations in response to the 2000-IU supplement across time. Furthermore, carotid-femoral PWV increased from baseline (5.38 +/- 0.53 m/sec) to posttest (5.71 +/- 0.75 m/sec) in the control group (P = 0.016), whereas in the experimental group carotid-femoral PWV decreased from baseline (5.41 +/- 0.73 m/sec) to posttest (5.33 +/- 0.79 m/sec) (P = 0.031). Conclusion: Daily 2000 IU vitamin D supplementation may be effective in optimizing vitamin D status and counteracting the progression of aortic stiffness in black youth. Plasma 25(OH)D concentrations in response to the 2000 IU/d supplementation are negatively modulated by adiposity.

Source: J Clin Endocrinol Metab. 2010 Jul 21

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