Effect of daily sunscreen application on vitamin D: findings from the open-label randomized controlled Sun-D Trial

British Journal of Dermatology

Clinical Summary

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What was studied

A population-based, open-label randomized trial in Australian adults (18–70) not routinely using sunscreen or vitamin D compared routine SPF50+ application on days with UV Index ≥3 vs discretionary sunscreen use for about one year, measuring serum 25(OH)D at baseline and at the end of summer and winter.

Key findings

Adjusted mean change in 25(OH)D from baseline was +1.6 nmol/L with routine sunscreen vs +6.8 nmol/L with discretionary use; between-group effect −5.2 nmol/L (95% CI, −7.2 to −3.2). Vitamin D deficiency in the final sample occurred in 139 (46%) vs 115 (37%); prevalence ratio 1.33 (95% CI, 1.14–1.55).

Study limitations

Open-label design with participants unblinded; vitamin D deficiency was an exploratory outcome. Eleven randomized participants had no post-baseline 25(OH)D and were excluded.

Clinical implications

Routine high-SPF sunscreen use over a year led to lower 25(OH)D and more deficiency than discretionary use; regular sunscreen users may need vitamin D supplementation.