The purpose of this study was to demonstrate the feasibility of a phototherapy kiosk (PK) to engage community adults in health promotion and to stimulate production of circulating 25-hydroxyvitamin (OH)D as effectively as a vitamin D3 oral supplement (OS). Although optimal production of vitamin D comes from sun exposure, ultraviolet B radiation with a wavelength of 290 to 320 nm penetrates exposed skin and may produce vitamin D3 using a PK.
A prospective study was conducted with adults randomized to either six PK treatments or D3 OS for 10 weeks. Serum 25(OH)D was drawn at baseline, 10 weeks, and 14 weeks. Primary outcome was serum 25(OH)D level. Mann–Whitney test was used to assess continuous data and Chi squared test for pairwise comparisons of categorical data. Significance was set at P < .05.
With 18% attrition, final sample size was 88; OS, n = 45, PK, n = 43. Sample was mostly female (60%), median age 35 years, with no differences observed between groups for age, race/ethnicity, marital status, military affiliation, or season of enrollment. Median daily intake of calcium and vitamin D was well below the recommended daily allowance for each nutrient, and group. Baseline median serum 25(OH)D levels were similar. By 10 weeks, PK median level was 30 ng/mL (interquartile range [IQR] 25.8-37.0) and OS was 26 ng/mL (IQR 21.5-30.5), P = .02. The difference in 25(OH)D levels persisted at 14 weeks; the PK group returned to baseline, 27 ng/mL (IQR 22.0-32.5), and OS group declined to 21 ng/mL (IQR 17.0-30.0), P = .02.