Effect of multivitamin on serum 25-hydroxy vitamin D level in postmenopausal women: A randomized, double-blind, placebo-controlled trial.

Objectives: To determine the effects of multivitamin vitamin D 300 or 600 units on serum 25 hydroxyvitamin D (25(OH)D) level after 4 weeks of supplementation in postmenopausal women with vitamin D insufficiency.

Study Design: Randomized double-blind, placebo-controlled trial.

Methods: Postmenopausal women who had vitamin D insufficiency were recruited into the study. The participants were randomized to 3 groups of 4-week treatment period with multivitamin (GPO, Governmental Pharmacy Organization) 2 tablets (contained vitamin D2 amount 600 units), multivitamin 1 tablet (contained vitamin D2 amount 300 units) or placebo. At baseline and after 4 weeks of supplementation, serum 25(OH)D were determined with electrochemilumines-cence immunoassay (Cobas, Roche Diagnostics) and level change of 25(OH)D level were compared among the groups.

Results: Out of 144 participants, 49.3% had vitamin D deficiency (<20 ng/ml) and 50.7% had vitamin D insufficiency (<30 ng/ml). However, after 4 weeks of the GPO oral multivitamin, serum 25(OH)D levels significantly increased from 19.4 ± 6.3 ng/ml at baseline to 22.2 ± 5.2 ng/ml (p = 0.01) and from 19.5 ± 5.0 ng/ml to 23.3 ± 5.2 ng/ml (p < 0.01) in the groups receiving vitamin D 300 IU and 600 IU/day, respectively. Approximately, 10% of those who took vitamin D had serum 25(OH)D level above the insufficiency level within 4 weeks. There was no significant changes of serum 25(OH)D after 4 weeks in the placebo group.

Conclusions: Daily supplementation of the generic multivitamin containing vitamin D2 300 and 600 IU daily for 4 weeks significantly increased mean serum 25(OH)D from baseline up above the deficiency level.