Exploratory Study on the Role of Vitamin C in Promoting Health in Middle-Aged and Elderly Adults

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.