Nutrigenomics is the study of how nutrients and bioactive food compounds interact with the genome to influence gene expression, metabolism, and health. It examines, for example, how fatty acids activate transcription factors that regulate lipid metabolism, or how folate status affects DNA methylation patterns. The field promises a future of personalised nutrition: dietary advice tailored to genetic variants affecting lactose tolerance, caffeine metabolism, or folate processing. In animal agriculture, nutrigenomics already helps optimise feeds for growth and health. For human application, the science remains young; most diet-gene interactions have small effects, and commercial DNA-based diet tests often overpromise. Still, the core insight is reshaping nutrition science, moving it from one-size-fits-all recommendations toward an understanding of why individuals respond differently to the same foods.