This study isolated a novel low-molecular-weight <i>Schisandra chinensis</i> polysaccharide (SCP) that ameliorated UC and comorbid depression by remodeling gut microbiota, redirecting tryptophan (Trp) metabolism toward the indole pathway, and activating aryl hydrocarbon receptor (AhR). The gene discussed is AHR; the disease is depressive symptom measurement.