Can the use of vitamin D-fortified sunscreen cream be the solution to the vitamin D deficiency pandemic?

Current approaches to vitamin D supplementation are generally limited to its oral intake. In this experimental study, the effects of applying vitamin D-fortified sunscreen creams to the skin on the absorption, and therefore levels of serum vitamin D metabolites were investigated. Forty 8-week-old male Wistar Albino rats were used in the study. Eight rats (Group B) were sacrificed to determine the baseline values of biochemical parameters. The remaining 32 rats were randomly divided into 4 equal groups as follows: Group S, only the back skin of the rats were shaved; Group SD, only vitamin D₃ diluted with sunflower oil was applied to the shaved area; Group SC, only sunscreen cream was applied to the shaved area; and Group SDC, sunscreen cream fortified with vitamin D₃ was applied to the shaved area. Serum 25(OH)D₃ and 24,25(OH)₂D₃ levels were determined at the end of 8 weeks. Mean (± SD) serum 25(OH)D₃ levels of groups B, S, SD, SC, and SDC were determined as 17.7 ± 5.7, 13.5 ± 3.1, 54.1 ± 13.0, 19.6 ± 2.7, 67.2 ± 16.5 ng/mL, respectively. There were statistically significant differences in serum 25(OH)D₃ values between groups S and SD (p < 0.001) and between groups SC and SDC (p = 0.002). A positive correlation was found between serum 25(OH)D₃ and 24,25(OH)₂D₃ parameters (r = 0.772; p < 0.001). With this study, it was concluded that vitamin D-fortified sunscreen cream increases serum vitamin D levels by exerting transdermal activity. Further studies are required to confirm this observations.