Mediterranean diet components and dry eye disease: Current evidence and mechanistic insights

Background: Dry eye disease (DED) is multifactorial-disorder characterized by tear film instability, ocular surface inflammation, and bothersome symptoms that impair quality of life. Diet-based strategies are increasingly explored as adjuncts to standard care. Methods: We performed a narrative synthesis of clinical and pre-clinical studies evaluating MedDiet components or patterns in relation to DED outcomes. Results: Multiple clinical studies suggest that omega-3 intake can improve tear break-up time (TBUT), Schirmer wetting, and Ocular Surface Disease Index (OSDI) scores in subsets of patients; however, some major trials, particularly those using active placebos such as olive oil, have reported no significant benefit of omega-3 supplementation over control. Components of olive oil or other aspects of the MedDiet can exhibit anti-inflammatory effects, neutralize free radicals, and stabilize the tear film. Antioxidant vitamins, carotenoids, and other components of the MedDiet can help preserve the integrity of the epithelial layer and reduce oxidative stress in tears. Vitamin D can support barrier layer proteins and maintain the balance between T helper 17 cells (Th17) and regulatory T cells (Treg), with rapid associations observed between vitamin D levels and dry eye disease (DED) symptoms, as well as some early outcome studies. Evidence for the MedDiet as a whole is weak, while stronger evidence exists for its individual components, although this varies by concentration, duration of administration, patient population, and control group. Conclusion: Components of the MedDiet show promise in managing DED, particularly in specific DED phenotypes, but further trials with standardized outcomes are needed to confirm these findings.