Mushrooms have a long history of medicinal use, particularly in Japan, Russia and China, where they have a revered place in the pharmacopoeia of Traditional Chinese Medicine. Dietary supplements made from either whole medicinal mushrooms or mushroom extracts are becoming increasingly popular in the west. The most commonly used medicinal mushrooms include reishi, maitake, turkey tail, oyster, shiitake, and cordyceps.

 Research shows that the polysaccharides known as beta-glucans, found in many species of mushroom, have a positive effect on immune system function. In addition to general immune-enhancing properties, mushrooms are also used for specific conditions. Clinical studies show that mushroom extracts hold promise in treating hepatitis C, cancer, and HIV. Medicinal mushrooms also contain tocopherols and carotenoids, compounds with antioxidant activity, and some varieties, such as oyster mushroom, contain natural statins with cholesterol-lowering capabilities. Others, such as maitake and reishi, are able to help lower elevated blood sugar levels.