This intensive longitudinal study investigates the day-to-day stability and natural fluctuations of the gut microbiome in healthy adults over a 15-day period. While the human gut microbiome is a complex ecosystem, its baseline stability in the absence of disease or medical intervention remains insufficiently characterized due to low sampling frequency in prior research. By recruiting healthy volunteers for continuous daily sampling, this study aims to map temporal community structures and evaluate the stability of core microbiota. Additionally, the research utilizes Continuous Glucose Monitoring (CGM) to explore the potential relationships between microbiome dynamics, daily dietary intake, and host glycemic stability.

This non-interventional, observational study utilizes high-frequency sampling to capture biological and physiological dynamics under free-living conditions. Participants undergo a 15-day monitoring period involving the daily collection of saliva (5 mL) and stool (40 g) samples for microbial sequencing and functional evaluation. Simultaneously, participants provide samples of every meal consumed to allow for DNA sequencing of food sources, providing an objective record of dietary intake to correlate with microbiome shifts. Throughout the study, volunteers wear a CGM device to continuously record blood glucose data, which is integrated with microbial and nutritional datasets to differentiate intra-individual fluctuations from inter-individual differences. To ensure data integrity and participant safety, the study is overseen by a Data and Safety Monitoring Board and adheres to ethical standards approved by the Westlake University Ethics Committee.

Inclusion Criteria:

• Participants reside in Hangzhou

Exclusion Criteria:

• Refusing or unable to give informed consent
• Participants with chronic gastrointestinal diseases and take daily relevant medications
• Participants with metabolic diseases including diabetes, hypertension and cardiovascular diseases (CVD)
• Participants with craniocerebral trauma, cancer, liver disease, kidney disease, or other critical illness, or history of operation or medication
• Participants with bulimia nervosa, post-traumatic stress disorder (PTSD), chronic anxiety and depression or other critical neuronal disorder or history of relevant medication
• Being or to be pregnant or lactating.
• Participants with history of alcohol or drug addiction, or smoke above 15 cigarettes per day
• Concurrently participating other clinical trials.

Healthy young adults residing in Hangzhou