Advances in oral delivery systems for alpha-linolenic acid: mechanisms, bioavailability, and applications in functional foods

Alpha-linolenic acid (ALA) is an essential ω-3 polyunsaturated fatty acid abundant in flaxseed and perilla oils (40-60% of total oil content), offering multiple health benefits, including cardiovascular protection, anti-inflammatory effects, and neuroprotection. However, its oral bioavailability is severely limited by poor oxidative stability, low water solubility, and insufficient intestinal absorption. Oral delivery systems can overcome these barriers by encapsulating ALA, enhancing its stability, and promoting gastrointestinal absorption. Unlike previous reviews focusing on ALA sources, extraction, and bioactivities, this review uniquely addresses the gap by systematically summarizing recent advances in oral delivery technologies that enhance ALA bioavailability, with emphasis on their underlying mechanisms and integrated food applications. We outline the biological functions, metabolic pathways, and oral delivery challenges of ALA, and discuss how various delivery systems modulate digestion and absorption processes to improve bioavailability. Applications in functional foods, including dairy, bakery, and meat products, are also reviewed. Finally, considering current limitations in targeting specificity, carrier performance, and systematic evaluation, we propose integrating intelligent carrier design, precise delivery strategies, and comprehensive evaluation systems to advance next-generation ALA delivery platforms toward clinical translation.