Precision dietary strategies for enriching animal-derived foods with antioxidants and omega-3 fatty acids.

Functional food demand has driven research into dietary strategies that enhance the nutritional value of animal-derived foods. This narrative review (2010-2025; 225 studies) evaluates supplementation with selenium (Se), zinc (Zn), vitamin E (Vit E) and omega-3 polyunsaturated fatty acids (n-3 PUFAs) to enrich livestock-derived meat, milk and eggs, proposing a precision enrichment framework. Organic and some novel forms of Se and Zn generally show greater efficacy than inorganic sources in many studies, largely due to differences in bioavailability and metabolic handling. Potent synergies were identified between Se-dependent glutathione peroxidase and Vit E (extending antioxidant efficacy) and between plants (C18:3n3-rich) and marine oils (C20:5n3/C20:6n3-rich), yielding broad-spectrum lipid enrichment. Unlike monogastric animals, in ruminants, protected lipid forms are often more effective for improving transfer of unsaturated fatty acids into animal products by reducing ruminal biohydrogenation, although responses vary with lipid source, protection method, diet and species. However, high dietary unsaturation is positively associated with oxidative risk, generally warranting antioxidant co-supplementation to preserve product stability and shelf-life. Although some studies used inclusion levels above regulatory recommendations (EU/EFSA and FDA), comprehensive toxicological or environmental assessment were not conducted. Based on the available evidence, functional food development requires shifting from single-additive approaches to a "precision enrichment" framework integrating nutrient-specific deposition pathways, species-specific physiological barriers, and nutrient synergies/antagonisms. Effective biofortification is supported by current literature; however, to confirm commercial viability and environmental sustainability, future efforts should prioritize long-term toxicological assessments at high inclusion levels, rigorous human health intervention trials, and economic feasibility studies.