Mushrooms have traditionally been valued in Asia for their nutritional and medicinal qualities. The Coriolus versicolor or “Turkey Tail” mushroom has been investigated in numerous laboratory, animal and human clinical studies. Most of these studies have demonstrated that it does appear to have significant antimicrobial, antiviral and antitumor properties when used as a supplement to chemotherapy and/or radiotherapy. Human trials have included randomization, a process that decreases bias, but only one has used blinding, which would make them even more protected against biases.
The anti-cancer and immune stimulating properties of Coriolus versicolor have been attributed to two extracts from its cultured mycelium (thread-like extensions). These extracts are both protein-bound polysaccharides known as polysaccharide K (PSK) and polysaccharide-peptide (PSP). Hot water is required to extract these active components.