PSK is a proteoglycan extracted from the mushroom Coriolus versicolor (also known as Trametes versicolor, Yun Zhi in China, Kawaratake in Japan and Turkey Tail in Europe and America). The results obtained from a large number of published scientific studies and clinical trials have shown that PSK is a powerful immunomodulator capable of stimulating diverse immunological functions.
Medicinal mushrooms have been used for centuries throughout Asia but only recently has the extent of their benefits been recognised by Western countries. The known therapeutic benefits of Coriolus versicolor led Japanese researchers in 1971 to isolate an active substance from shelf mushroom or cultured mycelia. This active substance was called PSK.
PSK belongs to a class of immunomodulators known as biological response modifiers which are capable of stimulating immune functions and anti cancer activities. PSK enhances cellular immune function and stimulates the immune system in the body to help maintain a correct balance between cellular and humoral immunity.
Depressed immunity may be attributed to a number of causes including advanced age, stress, poor gut barrier function, infection, disease, exposure to carcinogens and treatment with immunosuppressive agents including chemotherapy and radiation therapy. PSK has been shown to significantly enhance quality of life and is also beneficial for maintaining general immune health with no reported adverse side effects.
Numerous clinical trials have established that 6 capsules, each of 500mg (a total daily dosage of 3g) is the accepted dosage of PSK (therapeutic dose).
A daily maintenance dose of 3 capsules of 500mg each is usually recommended.
Adverse reactions from PSK have not been reported since 1970 when clinical trials first began in Japan. However the Japanese Ministry of Health and Welfare reported that side effects were experienced in 114 patients of a total of 11,300 cancer patients who were given PSK as an adjunct with chemotherapy, the main effects being infrequent diarrhoea and nausea.
The extract from Coriolus versicolor has been used in China for about 500 years, and the purified extract PSK has been widely used in Japan for nearly 40 years. There have been over 300 studies conducted world wide with numerous published clinical trials. The evidence available dismisses any claims of “unproven, disproven, no evidence”.
The demand in both the Chinese and Japanese domestic market has taken the majority of available material but, due to the increase in commercial production of Coriolus versicolor mushroom, the pure extract produced from the mushroom is now becoming more accessible.
PSK could be taken for an indefinite period as clinical trials have documented evidence of patients taking PSK for more than 10 years.
Randomised controlled human clinical trials have documented that PSK has anticancer activity by boosting cellular immune function in the host to defend against tumour progression. PSK is well-tolerated and compatible as an adjuvant immunotherapy with surgery, chemotherapy an/or radiation therapy.
No, PSK is not expensive. On a recommended daily dose of 6 x 500mg capsules (3 grams), the cost per day should be about the same as a “cup of coffee at your local cafe”.