Gastrointestinal Transit Time

The goal of this study is to investigate the baseline of gastrointestinal transit time (GITT) and explore its relationship with other health indicators in 932 healthy adult volunteers. The main questions it aims to answer are: What are the population-level baseline values for GITT using the blue dye method? How is GITT associated with key physiological parameters including blood metabolic markers, life style, and stool characteristics? Participants will: Consume a standardized blue dye muffin after overnight fasting at the research center; Offer a finger prock blood samples for metabolic profiling; Collect stool samples for moisture measurement; Complete detailed questionnaires on diet, lifestyle, and bowel habits; Record the time of first blue stool appearance to determine GITT.