维生素A是维持人体正常生命活动所必需的脂溶性维生素,其生理功能包括构成视觉细胞内的感光物质、影响上皮组织稳定性及完整性、维持和促进免疫功能等.维生素A缺乏与呼吸系统疾病密切相关,预防和治疗维生素A缺乏症对于预防反复呼吸道感染和哮喘发作、减少支气管肺发育不良的发生均十分必要.“,”Vitamin A is a fat-soluble vitamin that is essential for the normal-life activities of the human body. Its physiological functions include forming photosensitive substances in visual cells, affecting the stability and integrity of epithelial tissues, maintaining and promoting immune functions. Vitamin A deficiency is closely related to respiratory diseases. Prevention and treatment of vitamin A deficiency is necessary to prevent recurrent respiratory infections and asthma attacks and reduce the occurrence of bronchopulmonary dysplasia.