Peptides in this category relate to the gastrointestinal tract, intestinal lining, and the biology of mucosal barrier function. Research often examines pathways involved in gut tissue repair, inflammation signaling, and the integrity of the intestinal barrier that separates the gut from the rest of the body. These compounds are discussed in educational contexts around digestive health, gut lining resilience, and barrier-function research, with much of the current evidence drawn from animal and preclinical models and human data varying by compound.