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

Summary

Following PRISMA standards, this review synthesized 22 studies (7 meta-analyzed; n=9470) and found that sunscreen blocks UV-B in vitro and, overall, use may reduce 25(OH)D levels. Given heterogeneity across designs and exposures, results point to a potential trade-off between photoprotection and vitamin D sufficiency.

Key Findings

• Included 22 studies (7 in meta-analysis) totaling 9470 participants.
• In vitro evidence consistently shows sunscreen blocks UV-B needed for cutaneous vitamin D synthesis.
• Pooled clinical evidence supports that sunscreen use can impair 25(OH)D levels, amid study heterogeneity.

Clinical Implications

For high sunscreen users or individuals at risk for deficiency, consider monitoring 25(OH)D and ensuring adequate intake via diet or supplements while maintaining photoprotection.

Limitations

• Substantial heterogeneity and limited number of studies included in meta-analysis
• Risk-of-bias tool (QUADAS-2) is tailored to diagnostic accuracy and may be suboptimal for intervention/exposure studies

Future Directions

Well-controlled longitudinal and randomized studies quantifying sunscreen application behaviors, UV exposure, and standardized 25(OH)D outcomes; evaluate mitigation strategies (dietary/supplemental vitamin D).