Lentil-Derived Bioactives for Gastrointestinal Health: Potential Complementary Interactions Among Peptides, Resistant...

Lentils (Lens culinaris; family: Fabaceae) are increasingly recognized as functional legumes with potential benefits for gut health because they provide bioactive peptides, resistant starch, and polyphenol-rich fractions within a shared food matrix. However, most existing studies have focused on individual lentil-derived compounds, and their matrix-dependent complementary interactions during digestion and fermentation remain insufficiently resolved. This review synthesizes current evidence on lentil-derived peptides, resistant starch, and polyphenols, with particular emphasis on their matrix-dependent complementary relationships, digestion-dependent transformation, microbial co-metabolism, and implications for intestinal barrier function. During gastrointestinal digestion and colonic fermentation, lentil proteins, resistant starch, and phenolic compounds undergo sequential transformation, yielding bioactive peptides, fermentable substrates, short-chain fatty acids (SCFAs), and phenolic metabolites that may collectively influence microbial composition and metabolic activity. Emerging evidence suggests that these interconnected processes may support gut health through microbiota-host crosstalk by modulating tight junction-related markers, reducing intestinal permeability, and maintaining epithelial homeostasis. Mechanistically, these effects have been associated with SCFA-mediated G protein-coupled receptor (GPCR) signaling, suppression of TLR4-NF-κB/MAPK inflammatory cascades, and activation of Keap1-Nrf2 antioxidant defenses, thereby attenuating oxidative stress and pro-inflammatory responses. Current evidence is more consistent with matrix-dependent complementary or convergent actions than with demonstrated synergy. At present, phenolic-rich fractions provide clear pathway-level evidence, whereas fermentation-linked carbohydrate effects are more strongly supported by microbiota- and in vivo-associated outcomes, and protein- or peptide-related mechanisms remain comparatively underdefined. Nevertheless, the evidence base remains limited by the scarcity of integrated studies, well-controlled human intervention trials, and factorial experimental designs capable of distinguishing complementary, additive, and truly synergistic effects among lentil bioactives. This review therefore highlights the need to move from describing coexisting beneficial effects toward formally testing interaction effects within physiologically relevant lentil matrices.