Sunscreen and 25-Hydroxyvitamin D Levels: Friends or Foes? A Systematic Review and Meta-Analysis.

Abstract

Objective: To evaluate the impact of sunscreen use on 25-hydroxyvitamin D (25(OH)D) levels, addressing conflicting findings from observational and interventional studies.

Methods: Potentially eligible studies were identified from the PubMed/MEDLINE, Scopus, and Web of Science databases from inception to November 2024, utilizing a search strategy incorporating terms related to "sunscreen" and "vitamin D." The studies eligible addressed the questions define based on the Population, Intervention, Comparator, Outcome framework: What are 25(OH)D levels in patients exposing to sun applying or not sunscreen? This review followed Preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality assessment and the risk of bias were analyzed using Quality Assessment of Diagnostic Accuracy Studies version 2.

Results: We included 22 studies in the qualitative synthesis, and 7 in the quantitative one, encompassing a total of 9470 participants. In vitro studies consistently showed that sunscreen blocks UV-B radiation, crucial for vitamin D₃ production, while population-based studies reported mixed findings. Some studies linked sunscreen use to lower 25(OH)D levels, particularly in individuals with limited sun exposure, while others observed no significant impact. Meta-analysis showed that the adoption of sunscreen is associated to a reduction of 25(OH)D serum concentration (standardized mean difference = -2 ng/mL, 95% confidence interval -3, -1) with a not important heterogeneity across studies (I-square = 37%, P = .15).

Conclusion: The existing evidence supports that sunscreen can impair vitamin D₃ synthesis, and as a result decrease serum 25(OH)D levels, but further research is necessary to determine the broader health implications and guide public health recommendations.