Effects of Eight-Week Supplementation Containing Red Orange and Polypodium leucotomos Extracts on UVB-Induced Skin Responses: A Randomized Double-Blind Placebo-Controlled Trial

Background/Objectives: Oral photoprotection is gaining attention as a complementary approach to conventional sun protection. This randomized double-blind placebo-controlled study evaluated the effects of an 8-week dietary intervention with a syrup supplement containing Polypodium leucotomos extract (PLE), Red Orange Extract (ROE), and vitamins A, C, D, and E on minimal erythema dose (MED), UVB-induced erythema (Δa*), and pigmentation changes (ΔMI). Methods: In total, 54 fair-skinned participants (phototypes I–III) were randomized into either the intervention (IP) or placebo group (n = 27 per group). MED, Δa*, and ΔMI were assessed at baseline after 2 and 8 weeks of supplementation. Results: Throughout the intervention, MED gradually increased, while Δa* decreased in the IP group. While these changes were not statistically significant after 2 weeks, they reached significance after 8 weeks of intervention. By the end of the study, the IP group exhibited a significant 23.8% increase in MED (from 0.447 ± 0.096 to 0.553 ± 0.142 J/cm2; p < 0.05) and a 46.2% reduction in erythema intensity (from 2.40 ± 0.94 to 1.29 ± 1.04 au; p < 0.0001). In contrast, ΔMI in the IP group (from 0.67 ± 0.81 to 0.82 ± 0.96 au) were comparable to those observed in the placebo group, with no significant differences between groups. Conclusions: These findings suggest that supplementation with PLE, ROE, and vitamins A, C, D, and E provides systemic photoprotection by enhancing UV tolerance and reducing erythema without affecting tanning response. This study supports oral supplementation as an adjunct to topical photoprotection, with prolonged use potentially yielding cumulative benefits.