Differential Effects of Commercial Food-Grade Carrageenan Preparations on DSS-Induced Colitis and Gut Microbiota in Mice

Carrageenan (CGN) is widely used in processed foods and is typically supplied as a commercial preparation blended with other hydrocolloids to improve gelling properties, rather than as a single purified polymer. However, safety evaluations and mechanistic studies have largely focused on CGN in isolation; as a result, the biological effects of commercial CGN preparations (CGNPs) under realistic exposure conditions are still insufficiently characterized. In this study, the structural characteristics of three commercial food-grade CGNPs intended for meat products, soft sweets, and jelly were investigated. Furthermore, their effects on colitis were assessed, along with their impacts on the gut microbiota and related metabolites. The results indicated that all three CGNPs were κ-type, but differed in monosaccharide composition and molecular weight, which may contribute to their biological differences. In vivo, the CGNP intended for soft sweets significantly reduced the disease activity index (n = 6/group, p < 0.05) and helped maintain colon length (n = 6/group, p < 0.05). This CGNP also markedly reduced the abundance of Escherichia-Shigella and Helicobacter, while increasing propionate levels (n = 6/group, p < 0.05). In contrast, CGNPs intended for meat products and jelly tended to exacerbate colitis and increased the abundance of Enterococcus, a genus associated with colitis. These findings reveal the application-specific biological effects of commercial food-grade CGNPs and provide a basis for optimizing the application of these preparations in the food industry.