Natural Agents for Preventing Skin Damage Induced by Visible Light: A Systematic Review of Preclinical and Clinical...

Visible light (VL), and particularly high-energy visible light (HEVL), reaching Earth's surface has emerged as a relevant contributor to skin damage. VL has been implicated in oxidative stress, inflammation, pigmentation disorders, and photoaging, especially in individuals with darker skin phototypes. As conventional sunscreens offer limited protection in the visible spectrum, increasing attention has been directed toward complementary photoprotective strategies, including the use of natural compounds with antioxidant and anti-inflammatory properties. This systematic review aims to evaluate and synthesize the available preclinical and clinical evidence on the photoprotective effects of natural compounds against VL-induced skin damage, emphasizing their mechanisms of action, efficacy, and safety.

A comprehensive literature search was performed to identify studies reporting validated objective outcomes, including colorimetric parameters, diffuse reflectance spectroscopy, or clinical grading scales. Eligible studies were included, qualitatively synthesized, and risk of bias was evaluated.

Preclinical studies demonstrated that natural compounds mitigated VL-induced oxidative stress, inflammation, and pigmentation-related pathways. Clinical studies showed that formulations containing natural compounds improved VL-induced erythema and pigmentation outcomes. However, considerable heterogeneity was observed in irradiation protocols, outcome measures, and study designs, precluding quantitative meta-analysis.

Overall, available evidence supports a protective role for selected natural compounds against VL-induced skin damage, particularly through antioxidant and anti-inflammatory mechanisms, with the strongest clinical evidence focusing on natural sources of polyphenols. Nevertheless, this review highlights the need for standardized phototesting protocols and well-designed clinical trials. Future research should focus on comparative efficacy, long-term safety, and integration of natural compounds into combined photoprotection strategies tailored to different skin phototypes.