Many foods can have many nutritional factors that can boost your immune system or prevent the development of other disease processes e.g.
1- Vitamin C
Chewable Vitamin
2- Vitamin D
3- Lactoferrin
4- Vitamin E
5- Zinc
6- Beta carotenes
Vitamin C
Vitamin C is present in many vegetables and fruits such as tomatoes, oranges, lemons, guava, potatoes and strawberries. Vitamin C is a natural antioxidant, which means that it prevents damage to our cell membranes. Also, Vitamin C can increase the endogenous steroids, which are natural anti-inflammatory drugs.
Vitamin D
Vitamin D is present abundantly in egg yolk, liver and cod liver oil. Vitamin D is essential for proper phagocytosis. Phagocytosis is the process by which white blood cells "eats" bacteria and viruses to destroy them.
Lactoferrin
Lactoferrin is a protein that is present in milk and is most abundant in breast milk. Lactoferrin binds iron and prevents bacteria from utilizing it. Iron is a very important factor for multiplication of bacteria.
Vitamin E
Vitamin E is present in oils, seeds and nuts. It is a natural antioxidant just like Vitamin C. Moreover, Vitamin E increases the activity of B lymphocytes which can produce antibodies. Antibodies are proteins that can destroy bacteria and viruses.
Zinc
Zinc is present in oysters, liver, lean beef, lamb, turkey and many other foods. Zinc is important for all of the rapidly dividing cells in our bodies, such as those of the intestines and the upper respiratory tract. Also, zinc is important for phagocytosis which has been described earlier. Recent studies have proved that individuals with deficient zinc in their diets have weak immune responses to infection.
Beta-carotenes:
Beta carotenes are precursors of vitamin A and are present in sweet potatoes, carrots, spinach, cilantro and fresh thyme. Vitamin A is of great importance for the integrity of the upper respiratory tract and gastrointestinal system. Moreover, beta-carotenes can increase the number of T cells and natural killer cells both of which are of vital importance in the function of the immune system.