Abstract Background: Nutrigenomics refers to the study of how diet influences the genomic expression and function of an organism. Diet is a significant factor that impacts metabolism, aging, and lifespan. Long-term dietary patterns can influence the risk of age-related diseases, including diabetes, cardiovascular diseases, hypertension, and cancer. While research in Drosophila melanogaster has focused on areas such as calorie restriction, high-sugar and high-fat diets, micronutrients, and disease-specific nutritional interventions, the effects of different combinations of macronutrients have not been adequately studied. This study aimed to analyze the impact of individual macronutrients, specifically flaxseed oil (a source of fat) and casitose (hydrolyzed milk protein), as well as their combinations, on longevity, antioxidant activity, and the expression of aging-related genes in D. melanogaster. Methods: The study examined the in vivo effects of different concentrations of flaxseed oil (120 μl, 240 μl, 480 μl, and 960 μl), casitose (125 mg, 250 mg, 500 mg, and 1000 mg), and their combinations with a base diet on longevity, antioxidant activity, and the expression of aging-related genes, namely manganese superoxide dismutase (Mn-SOD or SOD1) and copper–zinc SOD (Cu-Zn SOD or SOD2) in D. melanogaster. Results: The study found that flaxseed oil, casitose, and their combinations increased lipid peroxidation (LPO) activity, leading to the production of reactive oxygen species. However, these substances also enhanced the activity of the antioxidant enzymes SOD and catalase, which help combat-free radicals. Furthermore, the gene expression of SOD1 and SOD2 was upregulated, suggesting a potential mechanism for the observed improvements in lifespan. Interestingly, high doses of flaxseed oil (960 μl) were associated with decreased lifespan in the flies. Conclusion: The findings indicate that the optimal levels of flaxseed oil, casitose, or their combination can increase lifespan in Drosophila by upregulating the expression of the antioxidant enzymes SOD1 and SOD2. This provides insights into the potential of targeted nutrient combinations as a dietary approach to combat aging-related diseases.