Narrowband ultraviolet B three times per week is more effective in treating vitamin D deficiency than 1600 IU oral vitamin D₃ per day: a randomized clinical trial

Background: It is known that narrowband ultraviolet B (NB-UVB) radiation and oral vitamin D(3) supplementation can both improve serum levels of vitamin D, expressed as 25-hydroxyvitamin D(3) [25(OH)D(3) ]. However, surprisingly few studies have compared the effects of the two interventions in treating vitamin D deficiency.

Objectives: To compare the effect of NB-UVB exposure with oral vitamin D(3) supplementation on vitamin D levels in patients with vitamin D deficiency.

Methods: Seventy-three participants with vitamin D deficiency [25(OH)D(3) ≤ 25 nmol L(-1) ] were consecutively enrolled from February 2010 to May 2011, avoiding the summer period (June to September). The participants were randomized into two groups, one receiving full body NB-UVB exposure three times per week, the other receiving 1600 IU (40 μg) oral vitamin D(3) per day together with 1,000 mg calcium. Thirty-two participants completed the 6-week study period, 16 in each group. In both groups blood samples were obtained at baseline and after 3 and 6 weeks.

Results: We found a significantly greater increase in 25(OH)D(3) levels (mean) in the NB-UVB treated group (from 19·2 to 75 nmol L(-1) ) compared with the oral vitamin D(3) treated group (from 23·3 to 60·6 nmol L(-1) ) after 6 weeks of treatment (P = 0·02), accompanied by a significant decrease in parathyroid hormone for the whole group (from 5·3 to 4·2 pmol L(-1) , P = 0·028).

Conclusions: Full body NB-UVB three times per week is more effective in treating vitamin D deficiency than prescription of a daily oral intake of 1600 IU (40 μg) vitamin D(3) .