Efficacy of various prescribed vitamin D supplementation regimens on 25-hydroxyvitamin D serum levels in long-term care
ABSTRACT Objective: The aims of this study were to examine the efficacy among various vitamin D supplementation regimens on serum 25(OH)D concentrations and determine the minimal dose rate required to achieve sufficient serum concentrations (≥75 nmol/L) among older adults in long-term care (LTC). Design: A one-year medical history was abstracted from medical records, and a one-time blood draw to measure serum 25(OH)D concentrations was obtained. Individuals were stratified into vitamin D supplemented and non-supplemented groups. The supplemented group was further categorized into four treatment forms: single ingredient vitamin D2or3, multivitamin, calcium with vitamin D, or combination of the three, and by daily prescribed doses: 0-399, 400-799, 800-1999, 2000-3999, and >4000 IU/day. Setting: Five LTC communities in Austin, Texas. Participants: 173 older (≥65 years) adults. Results: Of the participants, 62% received a vitamin D supplement and 55% had insufficient (≤75 nmol/L) 25(OH)D serum concentrations. Individuals receiving single ingredient vitamin D2or3 supplementation received the highest daily vitamin D mean dose (2900 IU/d), while combination of forms was the most frequent treatment (44%) with the highest mean serum concentration (108 nmol/L). All supplementation doses were successful at reaching sufficient serum concentrations, except those <800 IU/d. Using a prediction model, it was observed that one IU/d of vitamin D supplementation resulted in a 0.008 nmol/L increase in serum 25(OH)D concentrations. Conclusion: Based on the predictive equation, results suggest that supplementation of 1500 IU/d of vitamin D2or3 or combination of vitamin D is most likely to achieve sufficient serum 25(OH)D concentrations in older adults in LTC.