Coriolus versicolor is a common tree fungus, often seen by hikers as a stiff, rounded, horizontal protuberance from tree trunks, with concentric lines of varying color. In traditional Chinese herbal medicine, this fungus is used to strengthen overall vitality and treat lung and liver problems as well as other conditions.

Currently, extracts of Coriolus versicolor called polysaccharide-K (PSK) and polysaccharopeptide (PSP) are under study as immune stimulants for use alongside chemotherapy in the treatment of cancer. These two related substances, made from slightly different strains of the fungus, are thought to act as “biological response modifiers,” meaning that they affect the body’s response to cancer.

According to most but not all reported trials, most of which were performed in Asia, both PSK and PSP can enhance the effects of various forms of standard cancer treatment.1-9

For example, in a 28-day double-blind, placebo-controlled study of 34 people with advanced non–small-cell lung cancer, use of Coriolusextracts along with conventional treatment significantly slowed the progression of the disease.2

It is thought that Coriolusextracts work by stimulating the body’s own cancer-fighting cells.3 PSK and PSP may also have cancer-preventive effects.

In addition, very weak evidence hints that extracts of Coriolus versicolor might be helpful for HIV infection.10