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.

Keywords: Vitamin D, Deficiency, Insufficiency