High-dose oral vitamin D3 supplementation in the elderly

Abstract

Daily dosing with vitamin D often fails to achieve optimal outcomes, and it is uncertain what the target level of 25-hydroxyvitamin D should be. This study found that large loading doses of vitamin D3 rapidly and safely normalize 25OHD levels, and that monthly dosing is similarly effective after 3-5 months. With baseline 25OHD∈>∈50 nmol/L, vitamin D supplementation does not reduce PTH levels. Introduction: There is concern that vitamin D supplementation doses are frequently inadequate, and that compliance with daily medication is likely to be suboptimal. Methods: This randomized double-blind trial compares responses to three high-dose vitamin D3 regimens and estimates optimal 25-hydroxyvitamin D (25OHD) levels, from changes in parathyroid hormone (PTH), and procollagen type I amino-terminal propeptide (P1NP) in relation to baseline 25OHD. Sixty-three elderly participants were randomized to three regimens of vitamin D supplementation: a 500,000-IU loading dose; the loading dose plus 50,000 IU/month; or 50,000 IU/month. Results: The Loading and Loading∈+∈Monthly groups showed increases in 25OHD of 58∈±∈28 nmol/L from baseline to 1 month. Thereafter, levels gradually declined to plateaus of 69∈±∈5 nmol/L and 91∈±∈4 nmol/l, respectively. In the Monthly group, 25OHD reached a plateau of ~80∈±∈20 nmol/L at 3-5 months. There were no changes in serum calcium concentrations. PTH and P1NP were only suppressed by vitamin D treatment in those with baseline 25OHD levels <50 and <30 nmol/L, respectively. Conclusions: Large loading doses of vitamin D3 rapidly and safely normalize 25OHD levels in the frail elderly. Monthly dosing is similarly effective and safe, but takes 3-5 months for plateau 25OHD levels to be reached. © 2008 International Osteoporosis Foundation and National Osteoporosis Foundation.