Vitamin A promotes growth, reproduction, and maintains various physiological functions such as bone, epithelial tissue, visual and mucosal epithelial secretion. Vitamin A and its analogues have the effect of preventing precancerous lesions. In the absence of growth, it shows growth retardation and dark adaptation ability, which leads to night blindness. Due to dryness, desquamation, excessive keratinization, and decreased secretion of lacrimal glands in the epidermis and mucosal epithelial cells, dry eye disease occurs, and the cornea is softened and perforated and blind. The airway epithelial cells are keratinized and lose cilia, making the resistance less susceptible to infection. The recommended intake of vitamin A in adults (RNI) in China is 800 ug retinol activity equivalent per day, and female is 700 ug retinol activity equivalent per day.  Foods containing more vitamin A include poultry, livestock liver, egg yolk, and milk powder. Carotene can be changed into vitamin A, reddish yellow and dark green vegetables in the small intestine mucosa, and contains more carotene in fruits.