In Japan, PSK is a prescriptive medication for use as an immunoadjuvant therapy agent in combination with chemotherapy, radiotherapy and surgical treatments of colorectal and gastric cancers. Recommended dosage of 3 g per day. Safety evaluations report that the product is extremely safe and complied with LD-50 test.
In other parts of Asia, PSK is sold as an OTC product in pharmacies and is to be taken in 500 mg capsules, or as an extract, or as a tea.
In the USA, PSK is marketed as a food supplement or a class of mushroom ‘immunoceuticals’ with known immuno-therapeutic properties.
The American National Cancer Research Centre has recorded PSK as an anti-cancer fungal substance suited for treatment regimens used in cancer management32,33, but PSK has not been evaluated by the Food and Drug Administration.
PSK Coriolus versicolor is available worldwide from various sources on the internet.