Efficacy of various prescribed vitamin D supplementation regimens on 25-hydroxyvitamin D serum levels in long-term care

Objective: The aims of this study were to examine the efficacy among various vitamin D supplementation regimens on serum 25-hydroxyvitamin D (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 1-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 categorised into four treatment forms: single-ingredient vitamin D-2or3, multivitamin, Ca with vitamin D or combination of the three, and by daily prescribed doses: 0-9 center dot 9, 10-19 center dot 9, 20-49 center dot 9, 50-99 center dot 9 and >100 mu g/d. Setting: Five LTC communities in Austin, Texas. Participants: One hundred seventy-three 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 D-2or3 supplementation received the highest daily vitamin D mean dose (72 center dot 5 mu g/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<20 mu g/d. Using a prediction model, it was observed that 0 center dot 025 mu g/d of vitamin D supplementation resulted in a 0 center dot 008 nmol/l increase in serum 25(OH)D concentrations. Conclusions: Based on the predictive equation, results suggest that supplementation of 37 center dot 5 mu g/d of vitamin D-2or3 or combination of vitamin D is most likely to achieve sufficient serum 25(OH)D concentrations in older adults in LTC.