(HealthDay News) – Black and white women respond similarly to vitamin D supplements and should be dosed similarly, according to a study published online Feb. 5 in the Journal of Clinical Endocrinology & Metabolism.

J. Christopher Gallagher, MD, from the Creighton University School of Medicine in Omaha, NE, and colleagues conducted a randomized trial to establish vitamin D3 dosing in postmenopausal white women. In a parallel trial, 110 healthy older black women were randomized to either placebo; vitamin D3 400; 800; 1,600; 2,400; 3,200; 4,000; or 4,800IU daily. All participants received calcium supplements. At 12 months, change in serum 25-hydroxyvitamin D (25[OH]D) and parathyroid hormone (PTH) levels were measured.

The researchers found that, at baseline, mean serum 25(OH)D was 13ng/mL (33nmol/L). When given supplements of 4,800IU, serum 25(OH)D averaged 50ng/mL (125nmol/L), compared to 47ng/mL (117nmol/L) in white women. At 12 months, serum PTH levels decreased significantly (P=0.008) in relation to serum 25(OH)D, but not supplement dose. Hypercalcemia occurred in 7% of participants and hypercalciuria occurred in 15% of participants; these events were unrelated to vitamin D dose.

“When the dose response of vitamin D on serum 25(OH)D in African-American women is compared with that of Caucasian women, the increase in serum 25(OH)D after vitamin supplementation is similar,” the authors write.

Bayer provided calcium supplements at no cost for this study.

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