Daily oral vitamin D3 regimen in similar cumulative doses is more effective than weekly oral vitamin D3 regimen in patients with vitamin D deficiency

Vitamin D deficiency is a common health problem worldwide, especially in the Middle Eastern region. Although various dosing regimens of vitamin D have been used for the treatment of vitamin D deficiency, it is still unclear as to which dosing regimen can efficiently increase the serum level of vitamin D in different patient population.

This study was designed to compare the efficacy of weekly and daily regimens of vitamin D3 in patients with vitamin D deficiency. Settings and Design: A randomized clinical trial was conducted in the autumn and winter of 2016 and 2017, Hamadan, Iran.

A total of 130 patients with moderate to severe hypovitaminosis D were allocated into two groups: weekly 50,000 IU (routine recommended dose for vitamin deficiency treatment) or daily 4,000 IU (safe upper limit dose of vitamin D per day) of oral vitamin D3 for 8 and 14 weeks, respectively. The serum levels of 25-OH-vitamin D were measured in all patients at baseline and at the end of the treatment period.

Results of this study showed that though both dosing regimens can be effective in increasing the serum level of 25-OH-vitamin D, higher percentage of the subjects in the daily regimen group achieved the sufficient serum level of 25-OH-vitamin D when compared to the weekly regimen group.

Accordingly, probably owing to better bioavailability of daily regimen of vitamin D3 and establishment of a more steady serum concentration compared with weekly regimen, it can be recommended as the preferred dosing regimen for effective treatment of vitamin D deficiency.