Omega-3 Fatty Acid Supplementation and Incident Age-Related Macular Degeneration in a United States Veteran Population: A Retrospective Cohort Study

Background: Higher intake of omega-3 fatty acids from food sources is associated with a reduced risk of age-related macular degeneration (AMD), but there are no recommended parameters for omega-3 fatty acid supplementation. The purpose of our study was to investigate whether fish oil supplementation protects against development of AMD in the US Veteran Affairs (VA) Corporate Data Warehouse. Methods: Patients ≥ 55 years without an AMD diagnosis at the initial eye examination who also had a 5-year follow up eye examination were included in this retrospective cohort study. Patients receiving fish oil supplementation from the VA pharmacy were categorized into the fish oil exposure group and matched 1:1 to a non-exposure control group. All patients were assessed for AMD development at the 5-year follow up eye examination. Results: AMD developed in 772 of 16,172 patients (4.8%) with fish oil exposure and 635 of 16,093 (3.9%) without fish oil exposure (relative risk (RR) = 1.21, 95% confidence interval (CI) = 1.09–1.34, p = 0.0003). Compared to controls, AMD risk was similar in low-dose (RR = 0.91; 95% CI = 0.65–1.27) and moderate-dose (RR = 0.93; 95% CI = 0.79–1.10) fish oil supplementation but higher in high-dose fish oil supplementation (RR = 1.32; 95% CI = 1.19–1.47). Conclusions: Fish oil supplementation did not protect against AMD in a US veteran population.