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


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  • Conflicts of interest
    None declared.

Morten K.B. Bogh.


Background  It is known that narrowband ultraviolet B (NB-UVB) radiation and oral vitamin D3 supplementation can both improve serum levels of vitamin D, expressed as 25-hydroxyvitamin D3 [25(OH)D3]. 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 D3 supplementation on vitamin D levels in patients with vitamin D deficiency.

Methods  Seventy-three participants with vitamin D deficiency [25(OH)D3 ≤ 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 D3 per day together with 1000 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)D3 levels (mean) in the NB-UVB treated group (from 19·2 to 75 nmol L−1) compared with the oral vitamin D3 treated group (from 23·3 to 60·6 nmol L−1) after 6 weeks of treatment (= 0·02), accompanied by a significant decrease in parathyroid hormone for the whole group (from 5·3 to 4·2 pmol L−1, = 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 D3.