During the new school season, many children are experiencing fever and colds. Why are some people prone to catching colds and other diseases, while others are not? Why do some people recover quickly when they get sick, while others have to endure for a long time? Nutrition is the material basis for maintaining normal immune function in the human body because the immune system plays a crucial role in it. With a strong immune system, one can resist the invasion of diseases and recover quickly even if infected; Otherwise, it is susceptible to the invasion of diseases, which can be severe and last for a long time. The strength of the human immune system is influenced by various factors, among which nutrition can be said to be the material basis for maintaining normal immune function in the human body. Malnutrition can lead to impaired immune system function and decreased resistance to pathogens, thereby promoting the occurrence and development of infections. What are the functions of proteins, vitamins, iron, and zinc closely related to immune function? Nutrients such as protein, vitamin A, vitamin C, vitamin E, iron, zinc, and selenium are closely related to the body's immune function. Insufficient intake can affect the normal immune function of the body. 1. Insufficient protein intake can lead to a decrease in local immunity of the skin and mucous membranes, which can easily cause the proliferation and spread of pathogens and reduce their ability to resist infections. 2. Vitamin A and vitamin A deficiency will affect the integrity of epithelial cells in the respiratory system, digestive system, urinary system, and increase the susceptibility of the body to respiratory and intestinal infectious diseases. 3. Vitamin C can enhance the body's ability to resist infections, and a deficiency can lower the function of the immune system. 4. Iron deficiency can reduce the body's ability to resist infections. 5. Zinc plays an indispensable role in the development of the immune system and the maintenance of normal immune function. What are the various nutrients required for human immune function that can be supplemented by eating? 1. Moderate intake of high-quality protein containing foods. Firstly, it is recommended to consume animal based foods, including lean meat, fish, eggs, and protein found in dairy products; Soy products are also a good choice. The protein in soy products is high-quality and easily utilized by the human body. Therefore, it is necessary to eat some animal based foods in moderation every day. According to the Chinese Dietary Guidelines for Residents (2022), it is recommended to eat 40-75 grams of livestock and poultry meat, 40-75 grams of aquatic products, 300-500 milliliters of milk, and one egg per day. 2. Regularly eat foods rich in vitamins A, E, and C. There are many foods rich in vitamins A, E, and C in our daily diet, which can be easily obtained. There are mainly four types: first, animal liver, including sheep liver, pig liver, chicken liver, duck liver, etc., which are rich in vitamin A and should be eaten regularly. Secondly, plant-based foods contain retinoids, which can be converted into vitamin A in the body. Carotenoids are mainly found in dark green or reddish yellow vegetables and fruits, including carrots, spinach, celery, mangoes, sweet potatoes, etc. Thirdly, vegetable oils, the germ of plant seeds, nuts, legumes, and cereal foods are rich in vitamin E. Fourthly, fresh vegetables and fruits are sources of vitamin C rich foods, including fresh dates, green peppers, kiwis, spinach, hawthorn, citrus, grapefruit, strawberries, etc. 3. Regularly eat foods rich in iron, zinc, and selenium. Animal blood, liver, soybeans, black fungus, and sesame paste are rich in iron, and it is recommended to eat some regularly; Shell seafood, red meat, animal organs, etc. are good sources of zinc, and it is recommended to eat them regularly. (New Society)