Clinical research has demonstrated that non-starch polysaccharides from natural sources exhibit protective and therapeutic effects on ulcerative colitis (UC). In this study, a non-starch polysaccharide (CYP-A) with a molecular weight of 1.54 x 10(3) kDa was isolated from a speciality Chinese yam (Dioscorea) variety, the Ma yam, consisting mainly of mannose and glucose. The results indicated that CYP-A alleviated colitis symptoms induced by dextran sulfate sodium (DSS), repaired the mucus barrier, and protected the integrity of the intestinal mechanical barrier. Furthermore, CYP-A suppressed pro-inflammatory cytokine production, reduced oxidative stress, and modulated the biological barriers by facilitating the colonization of norank_f-_Muribaculaceae, Dubosella, Faecalibaculum and Enterorhabdus, while reducing Escherichia-Shigella and Bacteroides. Notably, CYP-A reshaped the metabolic pathways related to steroid hormone biosynthesis as well as phenylalanine, tyrosine, and histidine metabolism. These findings highlight the potential of CYP-A as a nutraceutical for targeting UC and improving gut health.