A fully functioning immune system is an important component of long-term wellness. Phytogen combines four American and Chinese botanicals – Echinacea, Coptis, Astragalus, and Schisandra – in a formula that promotes optimal immune function. Studies have demonstrated the ability of Echinacea angustifolia to activate natural killer (NK) cells and enhance the ability of other cell types to engulf foreign substances. Berberine, a major active constituent of Coptis, inhibits the adherence of foreign organisms to red blood cells and epithelial cells; for example, on the walls of the bladder.* The Chinese botanical Astragalus membranaceus has the ability to naturally enhance the number of white blood cells. Much of the current research on Astragalus focuses on its immune-stimulating polysaccharides. Schisandra has been studied extensively in China and Japan for its immune-modulating effects and is recognized as being immuno-protective of the respiratory system.