Association between omega-3 polyunsaturated fatty acids and cataracts: results from a cross-sectional survey and mendelian randomization analysis

This study investigated the association between omega-3 polyunsaturated fatty acids (PUFAs) and cataract risk by combining observational and genetic approaches. A cross-sectional analysis of the National Health and Nutrition Examination Survey (2003–2008) showed that higher omega-3 PUFA intake was inversely associated with cataract risk (fully adjusted OR = 0.74, 95 % CI: 0.57–0.97, P = 0.041). This protective effect was corroborated by Mendelian randomization analyses using large-scale genetic data (inverse variance weighted OR = 0.92, 95 % CI: 0.86–0.99, P = 0.044), with consistent results across sensitivity analyses. Summary-data-based Mendelian randomization further identified ten genes linking omega-3 PUFA metabolism to cataract through pathways related to lipid biosynthesis, oxidative stress, and inflammation. These findings provide convergent evidence that omega-3 PUFA intake may reduce cataract risk and highlight putative molecular mechanisms underlying this association. • Omega-3 intake lowers cataract risk per NHANES data. • MR suggests omega-3 s causally reduce cataract risk. • ALA and EPA protect against cataracts more than DHA. • Transcriptome-wide MR identified finds 10 genes linking lipids to cataract risk.