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Concern about vitamin D deficiency is growing worldwide; but it is a particular problem in those who reside far from the equator. To determine the value of narrowband ultraviolet B (NB-UVB) therapy for improving vitamin D levels, investigators in Finland administered a 7-day course of ultraviolet light to 56 women, skin phototypes II and III.
Before phototherapy, 77% of the participants had vitamin D insufficiency (<50 nmol/L calcidiol), and 11% were vitamin D deficient (<25 nmol/L); their mean calcidiol concentration was 39.1 nmol/L. Patients received one of four phototherapy regimens: whole-body NB-UVB; NB-UVB to the head and arms only; NB-UVB to the abdomen; or solar simulation radiation to the face and arms. All subjects received a standard erythema dose of one third to 1 times the minimal erythema dose on the first day and twice that amount daily for the next 6 days. All four groups had significant increases in the mean serum vitamin D level. Whole-body NB-UVB and NB UVB to the head and arms produced the greatest increase (11.4 nmol/L and 11.0 nmol/L, respectively). NB-UVB to the abdomen only and solar simulation radiation to the face and arms were less effective (producing increases of 4.0 nmol/L and 3.8 nmol/L, respectively). The maximum increase in vitamin D level was observed 2 weeks after completion of therapy, and despite a gradual decline, vitamin D levels remained elevated relative to baseline 2 months later.
Vähävihu K et al. Narrowband ultraviolet B course improves vitamin D balance in women in winter. Br J Dermatol 2010 Apr; 162:848.
Comment
Although foods and milk are fortified with vitamin D in many countries, deficiencies in this vitamin are widespread. Vitamin D supplements are one therapeutic option. A common treatment regimen is 50,000 IU of vitamin D, one to two times/week for 2 to 3 months, but this may not be right for all individuals. Narrowband UVB light sources are widely available and have been shown to be less carcinogenic than other forms of phototherapy — certainly more effective and less carcinogenic than tanning beds. Once treatment protocols are optimized, the small amount of ultraviolet radiation administered and the long duration of its effect may eventually make NB-UVB attractive as a therapeutic modality for selected individuals with a low risk for skin cancer (e.g., blacks, older individuals with little actinic damage, and those who are vitamin D deficient in the winter).