Photoprotective Effects of Oral Coriander (Coriandrum sativum L.) Seed Oil Supplementation Against UV-Induced Skin Damage: Evidence from Two Randomized, Double-Blind, Placebo-Controlled Clinical Trials

Skin is constantly exposed to UV radiation. While topical sunscreens are the main preventative measure, oral photoprotective agents are emerging as promising systemic adjuncts, offering uniform, continuous protection. This study presents the results of two clinical trials designed to evaluate the efficacy of supplementation with a standardized coriander (Coriandrum sativum L.) seed oil (CSO) in mitigating UV-induced skin damage, in comparison with a placebo. The first trial investigated the effects of CSO supplementation on women with reactive skin, assessing UVA+B-induced skin erythema and tumor necrosis factor-alpha (TNF-α) release. The second trial included women of all skin types and, in addition to the outcomes mentioned above, examined UVA-induced lipoperoxidation. Measurements were taken before and after 56 days of supplementation. CSO supplementation led to a significant reduction in UV-induced skin erythema and associated TNF-α levels in both cohorts, with decreases of 11.8% and 24.1% in the reactive skin group and 18.1% and 18.7% in the cohort with all skin types, respectively. In women of all skin types, UV-induced skin lipoperoxidation was reduced by 31.9% at 4 h and by 69.9% at 24 h post-exposure. To the best of our knowledge, this is the first study reporting the photoprotective efficacy of CSO. This finding is attributed to CSO’s high petroselinic acid content and its known anti-inflammatory properties.