In this clinical study 22 subjects with Fitzpatrick skin phototype IV-VI irradiated with visible light have been supplemented during 28 days with 480 mg/d of Polypodium leucotomos extract (PLE). Irradiation were repeated and clinical Investigator’s Global Assessment scoring and spectroscopic evaluations were performed immediately, 24 hours, and 7 days after irradiation as well as 4-mm punch biopsies that were obtained for immunohistochemistry analysis: one from normal unirradiated skin and the other two twenty-four hours after irradiation, pre- and post-PLE, from sites irradiated with highest dose of visible light.

After irradiation with visible light, all subjects had immediate pigment darkening, persistent pigment darkening, and delayed tanning both pre- and post-PLE. For the highest visible light dose (480 J/cm²) spectroscopic assessments demonstrated a statistically significant decrease in persistent pigment darkening and delayed tanning post-PLE. In addition, there was a significant decrease in cyclooxygenase-2, and a trend towards decreases in the markers for cellular damage post-PLE. While there was a trend towards lower Investigator’s Global Assessment scores post-PLE, statistical significance was not reached possibly due to lack of sensitivity of the visual Investigator’s Global Assessment scoring system in detecting small changes.

In conclusion, an oral supplementation with Polypodium leucotomos extract have demonstrated good skin protective properties against visible light-induced damage.

Mohammad TF, Kohli I, Nicholson CL, et al. Oral Polypodium Leucotomos Extract and Its Impact on Visible Light-Induced Pigmentation in Human Subjects. J Drugs Dermatol. 2019;18(12):1198–1203