The purpose of this clinical trial is to understand whether oral vitamin C can help delay the aging of middle-aged and elderly individuals, search for sensitive biomarkers of human aging, and provide new paradigms and scientific guidance for aging intervention with small molecule drugs. The main questions it aims to answer are as follows:

• Can oral vitamin C effectively improve the aging-related indicators?
• What is the safety of participants when taking vitamin C supplements?

Researchers will compare vitamin C with a placebo to observe whether vitamin C is effective in intervening in the aging of middle-aged and elderly individuals. Participants need to:

• Take 2 tablets (250mg/tablet) of vitamin C or placebo after breakfast and dinner every day for 12 consecutive months;
• Go to the designated place for a face-to-face follow-up every 6 months and receive a telephone follow-up every 2 months, and pick up subsequent drugs during the follow-up;
• Honestly inform the medication situation during each follow-up;
• Report any discomfort or adverse reactions that occur during the treatment process to the researchers;
• Fill in a questionnaire about their own health status during each follow-up;
• After 6 months and 12 months of intervention, conduct a comprehensive health examination as required, including blood tests and other items.

Inclusion Criteria:

• Age: 55-65 years (for the experimental and control groups) or 18-70 years (for the baseline control group assessing aging changes).
• Health Status: Deemed to be in good health based on medical evaluation, including medical history, physical examination, laboratory tests, and cardiac monitoring.
• Weight: BMI within the range of 18.5-28 kg/m².
• Informed Consent: Capable of signing the informed consent form and complying with the requirements and restrictions outlined in the study protocol.

Exclusion Criteria:

• Disease Status:Uncontrolled medical conditions or any disease that, in the investigator's opinion, may pose an inappropriate risk or contraindication or interfere with the study's objectives, conduct, or evaluation.Severe chronic or acute diseases (e.g., cancer, heart failure, renal insufficiency, COPD, diabetes, active liver disease, metabolic acidosis, poorly controlled hypertension, epilepsy, recent cardiovascular events, inflammatory bowel disease, neurological disorders, infectious diseases, severe autoimmune diseases, etc.).
• Weight: BMI < 18.5 or BMI > 28.
• Substance/Alcohol Abuse: Ongoing alcohol or drug abuse, or excessive alcohol consumption.
• Medical History: History of gastrointestinal diseases, hyperuricemia, kidney or urinary tract stones, glucose-6-phosphate dehydrogenase deficiency, or paroxysmal nocturnal hemoglobinuria.
• Allergy: Allergy to vitamin C or any component of its formulation.
• Recent Medication Use: Use of high-dose vitamin C, vitamin E, low-dose aspirin, acarbose, metformin, NMN/NR, or other anti-aging/weight-loss drugs within the past 3 months.
• Informed Consent: Inability to provide informed consent.
• Other: Any physical condition that, in the investigator's opinion, may adversely affect the study process or outcomes.
• Clinical Research Participation: Participation in any other clinical research within 3 months prior to screening or during the study period, or receipt of chemotherapy, radiotherapy, biologic therapy, small-molecule therapeutic agents, or investigational drugs, with incomplete recovery from related side effects (excluding alopecia or potential neuropathy).

I have decided not to share the IPD from this study due to concerns about participant privacy and confidentiality. Our study will include multiple-omic data, including genomic data. There are legal and ethical considerations that restrict the sharing of sensitive health information and genetic information without consent. Furthermore, the resources required to prepare and manage the data for external sharing are currently beyond our capacity. Therefore, to ensure the protection of our participants and comply with ethical standards, we have opted not to share the IPD at this time.