Effect of Food-derived Active Components on Digestive Tract Health in Adults with Irritable Bowel Syndrome

The goal of this clinical trial is to learn if Bifidobacterium. animalis subsp. Lactis A6 Strain or resveratrol to improve the symptoms of diarrhea-predominate irritable bowel syndromes (IBS-D). The main questions it aims to answer are: 1. Does Bifidobacterium animalis subsp.Lactis A6 Strain or resveratrol improve the symptoms of IBS-D. 2. What is the optimal intervention dose of Bifidobacterium. animalis subsp.Lactis A6 Strain or resveratrol to improve IBS-D Researchers will compare Bifidobacterium. animalis subsp.Lactis A6 Strain or resveratrol interventions to placebo (one look-alike sunbstance that contains no interventions substance) to see if Bifidobacterium. animalis subsp.Lactis A6 Strain or resveratrol relief the symptoms of patients with IBS-D. Participants will: 1. Take Bifidobacterium. animalis subsp.Lactis A6 Strain or resveratrol every day for 30 days. 2. Visit the clinic once every 15 days for checkups and tests.