Eat more protein. Protein is the material basis of human immune defense function, so we should eat more foods rich in protein, such as lean meat, milk, fish, shrimp and beans.

Drink more tea. A chemical called "theanine" in tea can enhance the anti-infection ability of human body five times. Theanine can also mobilize human immune cells to resist viruses, bacteria and fungi.

Vitamin supplements. Vitamin C can inhibit the synthesis of nitrosamines, promote the formation of antibodies, enhance the phagocytosis of white blood cells and enhance the body's resistance. You can eat more fruits and vegetables containing a lot of vitamin C, such as strawberries, tomatoes, cucumbers and carrots. Vitamin A has protective effect on respiratory tract and gastrointestinal mucosa. Lack of vitamin A will reduce the body's antibody response, leading to a decline in immune function, and bacteria and viruses will take advantage of it. Supplementing vitamin A from food is a safe and effective health care method. Eating more carrots can enhance immunity, and the reasonable way to eat carrots is to fry or stew with enough oil.