Polysaccharide-K, also known as PSK, is a natural compound derived from the mycelium of the Coriolus versicolor mushroom, commonly known as the turkey tail mushroom. It is classified as a polysaccharide, which means it is made up of long chains of sugar molecules. PSK is often used as a dietary supplement and is recognized for its potential immune-boosting properties. Research has shown that polysaccharide-K may enhance the immune response by stimulating various immune cells, such as macrophages and natural killer cells. It is also studied for its potential benefits in supporting cancer treatment, particularly in conjunction with conventional therapies.