Westlake Frequent-sampling Cohort 2

This observational follow-up study extends a previously completed 15-day intensive longitudinal study (WeF) of the gut microbiome in healthy adults. The objective of WeF2 is to characterize the long-term stability and dynamics of the gut and oral microbiota in the same cohort across multiple timescales, and to determine whether the day-to-day variability patterns observed at baseline persist over months and years. Participants who completed the WeF baseline protocol will be invited to attend periodic follow-up visits for low-frequency biospecimen collection and to repeat the original 15-day high-frequency sampling protocol at planned intervals, beginning approximately six months after the WeF baseline and continuing at extended intervals thereafter. By combining sparse routine sampling with recurring high-density sampling windows, the study aims to distinguish the stable core microbiome from transient and seasonal fluctuations, to track gradual community shifts under free-living conditions, and to further explore relationships among microbiome dynamics, dietary intake, and host glycemic regulation over an extended observation period.

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.