The principal action of an immune booster is to stimulate the activity of T-cells. These cells attack foreign cells by producing antibodies. T-cells are directed by the thymus gland, and so a good immune booster will also encourage proper thymus gland functioning. Research has shown that the aforementioned nutrients stimulate T-cell activity and function. Studies have shown that vitamin C stimulates effector cells, which are a type of protective cell, and that it also protects effector cells from their free radical by-products.
Beta carotene deactivates free radicals.
Echinacea extract stimulates the formation of antibodies, inhibits hyaluronidase, responsible for spreading a virus throughout the body, and increases the production of interferon, involved in immunity. Astragalus, often packaged as the Chinese herb Qiang gan ruanjian tang, is known to stimulate the immune system. It activates T-cells, helps to produce interferon, and has been found to destroy viruses. White willow enhances the immune system by inhibiting the immune suppressant immunoglobulin PGE2. Certain mushrooms are gaining recognition as immune stimulants.