Introduction: Chronic constipation is intricately linked to gut inflammation and dysbiosis, yet effective therapies targeting these underlying mechanisms remain limited. Objectives: This study investigates the therapeutic potential of Kaili sour soup (KSS), a traditional fermented food, and its key metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in alleviating loperamideinduced constipation, with a focus on microbiota-immune crosstalk. Methods: A murine constipation model was established via daily loperamide gavage (10 mg/kg, 7 days). Mice received KSS, DOPAC, or PBS orally , followed by assessments of gastrointestinal transit (charcoal propulsion), fecal water content, inflammatory cytokines (ELISA, Western blot), and gut microbiota (16S rRNA sequencing). Serum metabolomics (LC-MS) identified DOPAC as a critical metabolite. In vitro, bone marrow-derived macrophages (BMDMs) were pretreated with DOPAC and stimulated with LPS to evaluate NF-κB signaling (RNA-seq). Results: KSS markedly improved constipation phenotypes, increasing intestinal transit rates by 61% (P