Reishi mushroom is known as the "mushroom of immortality" and has been used medicinally in China and Japan for thousands of years. Reishi has been studied for its potential to increase antioxidant capacity and boost levels of glutathione, an antioxidant that repairs cellular damage and regenerates other antioxidants. Research in breast cancer survivors has shown that supplementing with reishi may improve anxiety and depression symptoms and support better energy levels.