Clinical Research Directory

Inclusion Criteria: 1. Age 70-85 years. 2. Patients with informed consent after thorough explanation. Exclusion Criteria: 1. Participants of other clinical trials; 2. Antibiotics or probiotics usage within last 4 weeks; 3. Severe hepatic or renal diseases ((ALT \>3 times the upper limit of normal value, or end stage renal disease on dialysis or eGFR \<30 mL/min/1.73 m2, or serum creatinine \>2.5 mg/dl \[\>221 μmol/L\]); 4. History of large atherosclerotic cerebral infarction or hemorrhagic stroke (not including lacunar infarction and transient ischemic attack \[TIA\]); 5. Hospitalization for myocardial infarction within last 6 months; Coronary revascularization (PCI or CABG) within last 12 months; Planned for PCI or CABG in the next 6 months; 6. NYHA class III-IV heart failure; Hospitalization for chronic heart failure exacerbation within last 6 months; 7. Severe valvular diseases; Potential for surgery or percutaneous valve replacement within the study period; 8. Dilated cardiomyopathy; Hypertrophic cardiomyopathy; Rheumatic heart disease; Congenital heart disease; 9. History of dementia, Parkinson's disease, intracranial infection, intracranial tumor, schizophrenia, anxiety, depression; 10. History of neurosurgical operation; 11. History of gastrointestinal tumor, gastrointestinal surgery, inflammatory bowel disease; Hospitalization for peptic ulcer disease exacerbation within last 6 months or anticipated hospitalization for peptic ulcer disease the next 6 months; 12. Hypertension with uncontrolled blood pressure ≥180/110mmHg; 13. Diabetes Mellitus with uncontrolled fasting glucose level ≥200mg/dl (11.1mmol/L), or HbA1C\>8%; 14. Addicted to alcohol; Use of medication influencing cognitive function(i.e., antihistamine, antipsychotic); 15. General anesthesia within last 3 months; 16. Other severe diseases influencing the entry or survival of participants, such as malignant tumor or acquired immune deficiency syndrome, life expectancy \<1 year; 17. Impaired verbal communication who are incapable of providing their own informed consent, or incapable of self-care; 18. Special diet influencing microbiota (i.e. vegetarian); 19. Other conditions inappropriate for recruitment according to the investigators.