The turkey tail (Trametes versicolor) mushroom, named for its colorful wavy stripes, is known for its strong antiviral, antimicrobial and antitumor properties. These properties have been attributed to two polysaccharides, polysaccharide-K (PSK), also known as krestin, and polysaccharide-P (PSP). The Japanese government approved the use of PSK in the 1980s for treating several types of cancers, and it is currently used along with surgery, chemotherapy and radiation. PSK was shown to significantly extend survival at five years or beyond in cancers of the stomach, colon/rectum, esophagus, nasopharynx and lung (non-small cell types) in Japanese trials since 1970.
Polysaccharide-P (PSP) was discovered more recently and has been studied mainly in China. In double-blind trials, PSP significantly extended five-year survival in esophageal cancer patients. PSP significantly improved quality of life, provided substantial pain relief and enhanced immune status in 70-97 percent of patients with cancers of the stomach, esophagus, lung, ovaries and cervix.
Both PSK and PSP boosted immune cell production and alleviated chemotherapy symptoms. Research indicates that PSP may slow the growth of certain tumors and help protect the immune system, particularly from the effects of cancer treatment.
The United States has recently begun researching this powerful mushroom as well. A new $5.4 million research study focusing on turkey tail mushroom is now underway. It is being conducted by Bastyr University, the University of Washington and others and is funded by the National Institutes of Health (NIH). The U.S. Food and Drug Administration (FDA) approved a clinical trial for turkey tail extract, where they will allow patients with advanced prostate cancer to take it along with conventional chemotherapy. Another group of patients will be given chemotherapy with a placebo.
Additionally, a seven-year study funded by the National Institutes of Health and reported in November 2010 found that the use of turkey tail mushroom significantly boosted immunity in women who had been treated for breast cancer. Researchers at the University of Minnesota and Bastyr University conducted the study in women with stages I-III breast cancer who had completed radiation therapy or chemotherapy. Results showed that immune function was enhanced in the women who took daily doses of turkey tail in pill form and that none of the subjects suffered any adverse effects. The actual product used in the study was Host Defense Turkey Tail from Fungi Perfecti.