Marine Food Polysaccharides: Representative Structural Features, Immunomodulatory Effects, and Food Applications

Marine food polysaccharides (MFPs) are structurally diverse biopolymers shaped by the marine environment, with emerging roles in immune regulation and food design. This review summarizes the representative structural features of MFPs, and evaluates their effects on innate and adaptive immune responses and associated signaling pathways. The influences of molecular weight, sulfation, branching, and monosaccharide composition on biological activity are also discussed. In addition, this review discusses the applications of MFPs in food additives, packaging, delivery systems, and functional foods. Despite growing evidence, challenges remain in resolving higher-order structures, understanding bidirectional immune effects and maintaining stability in complex matrices. Advancing integrated structural and food design approaches could enable the rational use of MFPs as next-generation functional ingredients.