Inclusion Criteria:  Age 65~80 years old People who join the Elderly Health Examination Program in Cathay General Hospital in 2021  Exclusion Criteria:  Antibiotics use within one month Acute gastrointestinal illness within one week, such as vomiting and diarrhea History of gastrointestinal surgery History of inflammatory bowel disease Chronic gastrointestinal disease under medication treatment Cannot finish dietary record