Does using a high sun protection factor sunscreen on face, along with physical photoprotection advice, in patients with melasma, change serum vitamin D concentration in Indian conditions? A pragmatic pretest-posttest study

Background: Use of sunscreens on the face is becoming popular, and patients with melasma are prescribed sunscreen for use on the face. Results of a few Western studies on the effect of sunscreen use on serum vitamin D concentration are not applicable to Indian conditions.

Aims: To examine the effect of use of a high sun protection factor (SPF 50+, PA++++) sunscreen on face in patients with melasma on serum concentration of 25-hydroxyvitamin D.

Methods: Forty-five Indian patients (Fitzpatrick skin types III and IV) with melasma were advised to use a sunscreen with SPF 50 + for 3 months, 43 (33 female, 10 male; age 32.9 ± 8 years) completed the study. Patients staying outdoor for <4 hours applied sunscreen once daily after bath. Patients staying outdoors for >4 hours reapplied sunscreen 4 hours after first application. Patients were provided a container to measure the amount of sunscreen for use, which was approximately equal to recommended thickness. Compliance was tested by weighing the used tubes and tubes in use during monthly visits. Serum concentration of 25-hydroxyvitamin D was tested before and after the study period.

Results: Amount of sunscreen advised (100.5 ± 29.2 ml) and the actual amount used (96.6 ± 27.9 ml) were similar (P = 0.53, t-test). The difference between serum concentrations of 25-hydroxyvitamin D at the baseline (19.20 ± 9.06 ng/ml) and at 3 months (18.91 ± 8.39 ng/ml) was not significant (P = 0.87, paired t-test, 95% confidence interval of difference -3.33 to 3.92). No correlation was found between the amount of sunscreen used and the percentage change in serum 25-hydroxyvitamin D concentration at 3 months (rho = 0.099, P = 0.528, Spearman's rank correlation).

Limitations: Longer duration of application and a larger sample size may detect minor differences in vitamin D concentration.

Conclusion: Using a high SPF sunscreen on the face, along with physical photoprotection advice, in patients with melasma for 3 months does not influence serum 25-hydroxyvitamin D concentration in Indian conditions.