Ulva lactuca polysaccharides alleviate constipation in mice through repairing the intestinal barrier and regulating the gut microbiota

BACKGROUND: Constipation is a frequent chronic disease in the community, and osmotic laxatives can effectively alleviate symptoms. However, it is not suitable for long-term use. Dietary fiber is an alternative option, with a capacity to address intestinal barrier dysfunction and sustained microbial dysbiosis. Ulva lactuca polysaccharide (ULP) is an algal fiber. It contains high alduronic acid and sulfate groups and may contribute to constipation alleviation owing to its strong water retention capabilities. RESULTS: ULP to mice increased fecal water content and gastrointestinal propulsion rate. It enhanced hydrophilic interactions and restored intestinal motility-related peptides; motilin, gastrin and 5-hydroxytryptamine rose by 50.71%, 123.70% and 185.74%, respectively. ULP also decreased the TNF-α and IL-6 inflammatory factors by 37.8% and 49.1%, and sustained the integrity of the intestinal barrier. The 16S rRNA sequencing and metabolomics showed that ULP enhanced the enrichment of Lactobacillus (7.6-fold) and Muribaculum (5.4-fold). It synergistically increased levels of arginine and S-adenosylmethionine. CONCLUSION: ULP alleviated constipation by water retention, microbial modulation and metabolic signaling regulation. It offers a novel, multi-target strategy for constipation management. © 2025 Society of Chemical Industry.