Vitamin D supplementation does not significantly improve bone mineral density (BMD) in older patients, according to study results published in the American Journal of Clinical Nutrition. However, increasing doses of vitamin D can elevate plasma 25-hydroxyvitamin D (25[OH]D) concentrations.

To examine how vitamin D supplementation affects bone mineral density at the hip in older patients, researchers prescribed vitamin D3 to 379 adults ages ≥70 years (mean age, 75 years). For 12 months, each participant was randomly assigned to receive 1 of 3 monthly dosages: 12,000 IU, 24,000 IU, or 48,000 IU. The primary outcome was change in BMD at the hip, with secondary outcomes including dose effects on femur and femoral neck BMD, falls, and adverse events. Baseline characteristics were similar across all groups.

After 12 months, the researchers discovered no significant difference in BMD change at the total hip or femoral neck sites between the 12,000- and 24,000-IU groups (P =.39 and P =.43, respectively) or the 12,000- and 48,000-IU groups (P =.08 and P =.62, respectively). However, plasma 25(OH)D concentrations increased significantly in all 3 groups, going from an average of 40 nmol/L at baseline to 55.9 nmol/L in the 12,000-IU group, 64.6 nmol/L in the 24,000-IU group, and 79 nmol/L in the 48,000-IU group (P <.01 for all differences). Similarly, parathyroid hormone concentrations decreased across the groups, with a significantly greater reduction in the 48,000-IU group than in the 12,000-IU group (P <.01).

The researchers reported no between-group differences regarding adverse events. Overall, there were 249 falls among 141 participants and 3 cases of hypercalcemia.

Limitations to this study included an absence of a placebo comparator.

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“[T]here was no difference in [change in] BMD between the 3 dosages of vitamin D, which suggests no effect of the intervention or that all doses may have attenuated the anticipated decrease in BMD over 12 [months],” the researchers said, adding, “Monthly dosing with oral vitamin D3 is a safe and effective strategy to increase plasma 25(OH)D >25 nmol/L.”

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Reference

Aspray TJ, Chadwick T, Francis RM, et al. Randomized controlled trial of vitamin D supplementation in older people to optimize bone health. Am J Clin Nutr. 2019;108:1-9.