PSK has shown to enhance cellular immune functions in healthy subjects. A recent randomised, double blind, placebo controlled crossover study in normal healthy subjects showed that consumption of PSK (50 mg/kg body wt) together with an herbal extract from Salvia miltiorrhiza (‘Danshen’) known to be beneficial for the circulatory system enhanced cell-mediated immunity49.
The findings suggest that regular consumption of PSK may be beneficial for immunological functions by enhancing key pathways of cell-mediated immunity in healthy subjects. However, evidence relating to therapeutic use of PSK comes mostly from studies in cancer patients showing significant benefits from PSK immunotherapy when used in conjunction with surgery and radiation and/or chemotherapy. Positive results from numerous randomised controlled trials have been published for a number of malignancies, including colorectal, oesophageal, breast, and lung cancer. Some selected randomised controlled trials for each disease category published in peer-reviewed journals are shown in (Table 3 -Colorectal cancer). The results showed that PSK alone or given together with chemotherapy and/or radiation therapy following surgery significantly improved survival rates.