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Vitamin D Supplementation in Older Women

Beth Israel Deaconess Medical Center, Boston, Massachusetts.

Address correspondence to Susan L. Greenspan, MD, Professor of Medicine, University of Pittsburgh, Osteoporosis Prevention and Treatment Center, Kaufmann Medical Building, Suite 1110, 3471 Fifth Avenue, Pittsburgh, PA 15213. E-mail griffithsd{at}msx.dept-med.pitt.edu

Background. The purpose of this study was to determine if vitamin D supplementation, 400–800 IU daily, could effectively treat vitamin D deficiency and insufficiency over 3 months.

Methods. To test this hypothesis, we conducted a cross-sectional survey followed by a 3-month, open-label run-in phase prior to a randomized clinical trial. We enrolled 573 community-dwelling women age 65 or older, 373 of whom completed the run-in phase. All women received a daily multivitamin containing 400 IU of vitamin D and one to two calcium supplements containing 200 IU of vitamin D. We assessed bone mineral metabolism (including 25-hydroxyvitamin D and parathyroid hormone), markers of bone turnover, and bone mineral density.

Results. Of the 553 screened participants who had baseline vitamin D levels available, 16% had vitamin D deficiency (serum vitamin D < 10 ng/ml) and 48% had vitamin D insufficiency (serum vitamin D between 10 and 20 ng/ml). Only 36% of participants had normal vitamin D levels (serum vitamin D 20 ng/ml). Baseline vitamin D intake was negatively associated with serum parathyroid hormone (r = –0.29, p <.0001), and not associated with bone mineral density or bone resorption. Vitamin D deficiency was associated with decreased physical activity and slower gait. Of the 373 women who completed the run-in phase and received treatment with a multivitamin and vitamin D-containing calcium supplement, vitamin D deficiency decreased from 16% at baseline to 0% at 3 months, and vitamin D insufficiency decreased from 48% at baseline to 20% at 3 months (p <.001).

Conclusions. We conclude that vitamin D deficiency and insufficiency, which are common among ambulatory, community-dwelling elderly women, can be normalized in 80% of patients over 3 months with vitamin D supplementation of 400–800 IU/d.