Lentinus edodes is one of common and beloved mushrooms from East Asia. It is commonly called oak mushroom or shiitake. Shiitake is derived from the tree it is associated with the Shii tree (Castanopsis cuspidate) and the Japanese word for mushroom–take. The best oak mushroom is before freezing in winter time in Japan and China. It is currently being studied in respect to AIDS, fungal infections, seasonal flu, bronchial inflammation, and cardiac disease. Lentinan, which is present in the fruiting body and the mycelium, acts as a potent defense against bacterial and viral infection. In addition to the anti-bacterial activity, L. edodes also has potential anti-oxidant properties as methanol and water extracts of phenolic compounds have indicated high anti-oxidant activity.