Even taken in small amounts, it appears to reduce the duration and severity of illnesses. In some studies, Vitamin C has helped reduce the risk of hepatitis infection as well. 11 Zinc supplements appear to increase immune response. 12 Taking Zinc lozenges when a cold starts often shortens the duration and severity of the infection. It is unclear whether Zinc also acts to prevent infection.
Astragalus reduces autoimmune response such as that caused by rheumatoid arthritis and lupus .
Some of the components of Cat's Claw stimulate the immune system. 16 Echinacea supports immune function. It works both as a preventive measure and to treat infection once it has set in. 18 Echinacea works well both by itself and as an enhancer of traditional medical treatments. 19 Green Tea has antibacterial properties and stimulates the production of immune cells.