Plant-derived peptides and intestinal barrier function: Exposure-aware evidence for functional food development

Abstract

Plant-derived peptides are increasingly investigated as functional food ingredients with possible relevance to intestinal barrier biology. This review evaluates how claims concerning plant-derived peptides and intestinal barrier function should be judged. Particular attention is given to the edible matrix, processing history, gastrointestinal digestion, local exposure, and endpoint attribution. Evidence is discussed across plant protein sources, processing and fermentation, peptide identification, targeted peptidomics, digestion-stage quantification, epithelial and microbiota-related models, and food matrix effects. The review does not present a systematic review conducted under the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework or a clinical efficacy assessment; instead, it provides an exposure-aware evidence map for deciding whether a peptide-containing material has been tested at the correct exposure layer. Available studies support peptide release from plant proteins, sequence-level detection of candidate peptides, and model-based effects on transepithelial electrical resistance (TEER), tracer permeability, junctional markers, inflammatory and oxidative-stress signals, mucus-associated responses, and microbiota-linked metabolites. These readouts do not carry the same evidential weight. Plasma detection, Caco-2 transport, hydrolysate activity, computational prediction, and animal-model responses each address different questions about availability, local exposure, attribution, or biological plausibility. For functional food translation, stronger studies will connect defined peptides, peptide fractions, or peptide-containing matrices with staged digestion, measured exposure, attribution controls, safety assessment, and food matrix design within the same sample-to-test workflow. The central methodological contribution is a six-level exposure-aware framework that organizes evidence according to increasing translational weight. It traces the progression from candidate prioritization and sequence confirmation through food matrix quantification and gastrointestinal exposure to barrier validation, attribution, and dietary or human translation.