Pharmacokinetics of daily versus monthly vitamin D3 supplementation in non-lactating women

This study compared serum cholecalciferol and 25-hydroxyvitamin D (25(OH)D) concentrations over four weeks in healthy, nob-pregnant, non-lactating females aged 18-40 years, Who were randomized to oral cholecalciferol 5000 international units (IU) daily for 28 days or a single dose of 150 000IU. The study was conducted in Rochester, MN in March and April of 2010. We found no difference in mean 25(OH)D between treatment groups on study day 0 or day 28 (P=0.14 and 0.28, respectively). The daily group had 11 more days of detectable serum cholecalciferol than the single-dose group (P<0.001). There was no difference observed in cholecalciferol area under the curve (AUC(28)) between groups (P=0.49). However, the single-dose group had a significantly greater mean 25(OH)D AUC(28) compared with the daily group (P<0.001).