Produced in the bone marrow, T cells are lymphocytes that attack foreign antigens. It seems that the amount of vitamin C needed is uncertain, but some studies suggest that it takes much more than the recommended RDA of 60 milligrams to reduce the risk of upper respiratory tract infections. Zinc - unfortunately for some of us, oysters are the easy winner here. But, beans are also a good source of zinc. It is also essential to another part of the immune system called humural immunity, which works by chemically inactivating incoming bacteria.
Protein is used by the body for energy and the body needs more energy to fight off illness.
These cultures crowd out harmful bacteria and other unwanted microorganisms. Soy yogurt also contains these cultures. If I were going to eat a dairy product, it would have to be organic and yogurt would probably be my first choice. In addition to boosting the immune system, it is also a good source of calcium and protein.