Microbes and the human body maintain a complex relationship of interaction and influence. Different regions, altitudes, and dietary habits have different degrees of influence on the composition of children's intestinal flora. Therefore, the development and maturation process of children's intestinal flora in plateau areas was discovered, and its relationship with children's immunity, metabolism, and growth was understood. The mechanism of action of children's intestinal flora on immunity, growth and development was further analyzed by comparing it with people in low-altitude areas, to provide a scientific basis for improving children's health in plateau areas.

This observational study aims to gain a deeper understanding of the interactions and influence of microbes on the human body. By comparing the gut microbiota composition of children in different regions, at varying altitudes, and with distinct dietary habits, the study aims to answer two key questions:

What are the characteristics of children's gut microbiota in different regions, at different altitudes, and with different dietary habits? What is the relationship between the development and maturation process of children's gut microbiota in plateau areas and their immunity, metabolism, and growth? Participants will be asked to provide fecal samples for analysis during the study. They may also be asked to answer questionnaires about their lifestyle factors such as diet and physical activity. The comparison group is included, researchers will compare the gut microbiota composition and diversity of children in low-altitude areas with those in plateau areas to assess any differences in their gut microbiota profiles. By comparing these differences, the mechanism of action of children's gut microbiota on immunity, growth and development can be further analyzed. The findings of this study aim to provide a scientific basis for improving children's health in plateau areas.

Inclusion Criteria:

• Children aged 1-3 years old
• Both men and women;
• The child's legal guardian signed the informed consent to participate in the study.
• The legal guardian of the child commits to follow the study procedures and cooperate with the entire study process

Exclusion Criteria:

• Probiotics or antibiotics within 1 month
• Associated with clinically significant abnormalities in liver and kidney function, nervous system, respiratory system, and coagulation function as determined by the investigator
• Unstable vital signs;
• Have other underlying medical conditions
• Individuals deemed unsuitable for this clinical trial.

heathy children aged 1-3 years old