Native Americans traditionally used echinacea to treat a variety of disorders, primarily infections and other conditions where enhancement of the immune system was needed. Echinacea's therapeutic efficacy was recognized by Western medical science in the late 19 th century. Today, echinacea is best known as a non-specific, immuno-supporting botanical. Zinc is an essential trace element required for the activity of over 300 enzymes and is involved in most major metabolic pathways. Zinc participates not only in catalytic processes, but also in the structure and stability of some regulatory proteins. Laboratory and clinical studies have shown that Eleutherococcus senticosus increases phagocytosis and stimulates lymphocyte activity in response to biological or physical stress. Preparations of Eleutherococcus increase in vitro granulocyte and monocyte phagocytosis of Candida albicans by over 30%. It has been suggested that Eleutherococcus stimulates the production of interferon, thus enhancing the functioning of macrophages, natural killer cells, and cytotoxic T cells. Nutrients such as garlic and Korean ginseng can also play important roles in the support of healthy immune function.