Effects of a dry-heated whey protein isolate-glucose preparation on colonic homeostasis in mice

Milk-derived Maillard reaction products (MRPs) have been associated with systemic adverse effects, yet their impact on intestinal health remains poorly characterized. This study investigated the effects of a dry-heated whey protein isolate (WPI)-glucose preparation (WPIG-36) on colonic barrier in mice. Prolonged dry heating promoted Maillard reaction progression, as reflected by increased 5-hydroxymethylfurfural and pentosidine levels and enhanced browning-related absorbance. Compared with the unheated WPI-glucose preparation, administration of WPIG-36 was associated with impaired colonic barrier integrity and reduced crypt depth and width. WPIG-36 also altered colonic mucosal and immune homeostasis, as indicated by decreased colonic mucin2 (MUC2), transforming growth factor-β1 (TGF-β1), and interleukin-4 (IL-4) levels and an elevated serum diamine oxidase (DAO) level. Gut microbiota analysis revealed an increased relative abundance of Rikenella and decreased abundances of Akkermansia and norank_f__norank_o__Clostridia_vadinBB60_group following WPIG-36 administration. These microbial alterations were significantly associated with fecal short-chain fatty acid concentrations and markers of colonic homeostasis, including DAO, MUC2, TGF-β1, and IL-4. Metabolomic profiling further demonstrated that WPIG-36 administration markedly perturbed amino acid metabolism, with arginine biosynthesis among the most significantly affected pathways. Collectively, these findings demonstrate that dry-heated WPI-glucose preparation disrupts colonic barrier homeostasis in association with gut microbiota remodeling and altered amino acid metabolism. These effects may reflect Maillard reaction-associated changes generated during thermal processing, rather than effects attributable solely to individual MRPs, highlighting the importance of controlling thermal processing conditions in food processing, particularly for extensively heated foods.