Effects of narrowband ultraviolet B exposure on serum 25-hydroxyvitamin D concentrations: A pilot study.

It is known that ultraviolet B exposure increases serum 25-hydroxyvitamin D(25(OH)D) concentrations. However, little is known about the influence of narrowband ultraviolet B exposure from a light-emitting diode (NBUVB-LED) on serum 25(OH)D levels. Thus, the purpose of this study was to investigate the effect of NBUVB-LED exposure on serum 25(OH)D concentrations. Two healthy adults were enrolled in this pilot study. Their skin was exposed to ultraviolet B light (60 mJ/cm2) 3 times a week for 4 weeks in the first intervention and every day for 4 weeks in the second intervention. Serum levels of 25(OH)D were measured every 2 weeks. Serum 25(OH)D levels were decreased in both subjects at the end of the first intervention (32.1 → 21.4 ng/mL, 33.9 → 21.4 ng/mL, respectively), whereas serum 25(OH)D levels were increased in the 2 weeks of the second intervention (29.5 and 28.0 ng/mL, respectively). At the end of the second intervention, the 25(OH)D concentrations were 19.0 and 20.4 ng/mL, respectively. NBUVB-LED exposure might increase serum 25(OH)D concentrations. Future studies should expand the number of participants and adjust for confounding factors.