Vitamins are a class of trace organic substances that humans and animals must obtain from food in order to maintain normal physiological functions. They have important roles in human growth, development and metabolic processes, and different types of vitamins have different roles. When the body’s immunity is low, vitamin C and vitamin A can be supplemented to help improve the body’s immunity. Vitamin C can help maintain the integrity of the skin and mucous membranes, thus keeping most of the bacteria and viruses out of the body and reducing the attack of diseases, and it can also promote the phagocytosis of phagocytes. In addition, vitamin C promotes the differentiation and proliferation of lymphocytes and the formation of antibodies leading to increased immunity of the body, thus reducing the probability of diseases such as upper respiratory tract infections. Vitamin A is involved in the immune process of cells, improving immune function by enhancing the viability of macrophages and natural killer cells as well as altering the growth or differentiation of lymphocytes. In addition, vitamins that help maintain the integrity of epithelial cells and promote epithelial cell differentiation also contribute to resistance to disease-causing agents. In addition, vitamin D and vitamin E are also very important for the maintenance of normal physiological functions of the body, so you can consider taking multivitamins to help improve the immunity of the body.