Engineering marine functional foods for gut–kidney axis modulation through sustainable food technologies and precision nutrition

Research on marine functional foods is shifting from their use as sources of isolated bioactive compounds toward engineered food systems that combine sustainable processing, targeted gastrointestinal delivery, and precision-nutrition approaches. This review discusses how diverse marine biological resources, including macroalgae, marine animals, and marine microorganisms, together with valorized side streams from seafood processing, can be transformed into standardized functional ingredients through green extraction, biorefinery, fermentation, membrane technologies, and food-grade delivery systems. These engineering strategies can enhance ingredient stability, bioaccessibility, and controlled release, thereby providing a technological basis for investigating microbiome-mediated pathways relevant to the gut–kidney axis. For example, fucoidan-rich marine polysaccharide fractions may act as microbiota-accessible substrates, with processing-dependent structural characteristics potentially influencing microbial fermentation, short-chain fatty acid production, intestinal barrier regulation, and downstream inflammatory pathways relevant to renal homeostasis. Evidence from marine ingredients and broader microbiome research suggests potential effects on intestinal barrier integrity, short-chain fatty acid production, and gut-derived metabolites associated with renal stress; however, direct clinical evidence demonstrating gut–kidney-axis modulation by engineered marine functional foods remains limited. Finally, we highlight how multi-omics, artificial intelligence, and precision nutrition can support individualized formulation design and biomarker-guided interventions. Integrating sustainable food engineering with microbiome science provides a translational framework for developing next-generation marine functional foods for metabolic and kidney health. Together, this framework positions marine functional foods not as uniformly beneficial health products, but as source-specific and deliberately engineered food systems whose biological effects depend on composition, processing, delivery, and host context.