Eggshell Membrane in Gut Health: Processing-Dependent Redox, Barrier, Immune, and Microbiome Effects

Gut health is maintained through interactions among intestinal barrier integrity, microbial homeostasis, host-immune function, and redox balance. Eggshell membrane (ESM), a protein-rich poultry by-product, contains structural components and derived peptides with antioxidant and anti-inflammatory activity in experimental systems. Increasing evidence indicates that ESM preparations can also influence epithelial barrier responses, intestinal inflammation, microbial community composition, and microbial metabolites. Because native, micronized, hydrolyzed, fractionated, and formulated ESMs differ in physical and chemical properties, processing is likely to influence gastrointestinal fate and biological activity. This review integrates chemical, cellular, animal, and human evidence to connect preparation-dependent properties with gastrointestinal exposure and intestinal redox, barrier, immune, and microbiome responses. It also considers oral delivery, dose, safety, and experimental approaches needed to resolve mechanism and translation. The evidence supports a biologically coherent intestinal-health framework for ESM, while controlled human studies are still needed to establish clinically meaningful gut-health effects and an effective intestinal dose.