Inclusion Criteria:  Clinical diagnosis of acute ischemic or hemorrhagic stroke Admission within 12 hours Aged 18-45 years  Exclusion Criteria:  History of neurological diseases, myocardial infarction, renal and hepatic abnormalities and metabolic diseases Combined with tumors, inflammatory bowel disease and other digestive system diseases Combined with serious life-threatening diseases or condition Any antibiotics, probiotics or prebiotic treatment within 3 months Deteriorate and die before collecting faecal samples