Oxidative Stability and Nanoencapsulation of Marine Omega-3 LC-PUFAs for Sustainable Aquaculture and Human Health

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs) that make farmed fish valuable to human health, given their bioactivity and highly unsaturated structure that also renders them exceptionally prone to oxidation during feed manufacture and storage, within the fish, and along the supply chain to the consumer. Preserving the oxidative stability, and hence the biological value, of these fatty acids is therefore a central challenge for sustainable aquaculture, made more acute by the replacement of omega-3-rich, oxidatively buffered fish oil with terrestrial oils that lower LC-PUFA content and shift the pro-/antioxidant balance of aquafeeds. Adopting an integrative feed-to-fish-to-consumer perspective, this review examines the strategies proposed to retain and protect EPA and DHA in farmed fish, distinguishing the physiological requirements of fish from the nutritional targets relevant to humans. We first appraise, comparatively, fish oil replacement, finishing diets and nutritional programming, showing that recovery of EPA and DHA is species-, tissue- and context-dependent and seldom complete, with EPA, a key eicosanoid precursor, preferentially catabolised. Through a focused, reproducible literature search, we then evaluate antioxidant-oriented nanoencapsulation as a means of shielding marine LC-PUFAs from oxidation and improving their stability and bioavailability. Although nanoencapsulation consistently enhances oxidative stability and, in the few in vivo studies available, fish performance, the evidence is constrained by heterogeneous and frequently incomplete physicochemical characterisation, scarce storage stability and in vivo data, and largely unaddressed safety, environmental-fate, regulatory, scalability and consumer-acceptance concerns. We conclude that protecting omega-3 oxidative stability will require combining well-characterised delivery systems with species-appropriate nutrition, and we set out the standardised characterisation, required in vivo validation, and integrated safety and life-cycle assessment needed to realise antioxidant-protective, nanotechnology-enabled aquafeeds.