Supplementary signals: poor adaptability to dark environment, dry corneas, dry hair, or infants who choke frequently, reduced ability to fight infection and recurrent respiratory infections and diarrhea. Applicable people: Computer users, businessmen and infants with insufficient intake of breast milk. Expert analysis: prolonged staring at the computer screen, or mental stress is prone to vitamin A deficiency. Signs of excess: skin rash, itching, anorexia, bone pain, headache, vomiting, etc. Foods rich in vitamin A: milk, carrots, animal liver (lamb liver, etc.), green garlic, cabbage, soy products, eggs, fish, walnuts, bok choy, cabbage, tomatoes and fresh fruits, etc.