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Dose response to vitamin D supplementation among postmenopausal African American women

Dec 21, 2007

Researchers from the Bone Mineral Research Center in Winthrop University Hospital in Mineola, NY wanted to determine the response of serum 25-hydroxyvitamin D [25(OH)D] to oral vitamin D3 supplementation in an African American population because the reports on the dose response to vitamin D were derived from white men and women.

208 healthy black postmenopausal women participated for a period of 3 y. The participants received 800 IU per day of oral vitamin D3 for the initial 2 years and 2000 IU for the third year. Supplementation with 800 IU a day of vitamin D3 raised the mean serum 25(OH)D concentration from a baseline of 46.9 nmol/L to 71.4 3 mo. The mean concentration of serum 25(OH)D was 87.3 nmol/L 3 mo after supplementation increased to 2000 IU per day. All participants achieved a serum 25(OH)D concentration greater than 35 nmol/L. 95% achieved a concentration greater than 50 nmol/L, but only 60% achieved a concentration greater than 75 nmol/L.

On the basis of these findings, an algorithm for prescribing vitamin D so that patients reach optimal serum concentrations was developed. The algorithm suggests a dose of 2800 IU per day for those with a concentration initially greater than 45 nmol/L and a dose of 4000 IU/d for those with a concentration initially less than 45 nmol/L. Conclusions: Supplementation with 2000 IU per day of oral vitamin D3 is sufficient to raise serum 25-hydroxyvitamin D concentrations to greater than 50 nmol/L in almost all postmenopausal African American women. However, higher doses were needed to achieve concentrations greater than 75 nmol/L in many women in this population. The study is published in the December 2007 issue of the American Journal of Clinical Nutrition.