Turkey Tail (Coriolus / PSK)

The most clinically tested medicinal mushroom in oncology.

What it is

Turkey Tail mushroom (Trametes versicolor / Coriolus versicolor) contains PSK (polysaccharide-K, also called Krestin) and PSP — immune-modulating beta-glucan compounds. PSK is an approved cancer treatment adjunct in Japan, prescribed alongside standard chemotherapy.

Why it matters

PSK significantly enhances NK cell and T-cell activity while modulating tumour-associated immune suppression. In Japan, PSK (Krestin) is prescribed routinely for gastric, colorectal, and lung cancer patients receiving chemotherapy. It has demonstrated ability to reduce recurrence rates and improve survival in randomised trials.

The evidence

Over 30 randomised controlled trials, primarily from Japanese oncology. A high-quality systematic review found PSK supplementation improved 5-year survival by approximately 9% in colorectal cancer patients receiving chemotherapy. PSK is arguably the most evidence-backed functional mushroom supplement in oncology — with pharmaceutical-grade trial data from Japan.

This information is for educational purposes and does not constitute medical advice. Always discuss supplement use with your care team, particularly if you are undergoing active cancer treatment.

Dosing

2–3g/day of standardised extract specifying PSK or beta-glucan content. Quality varies significantly — loose mushroom powder often has minimal PSK. Look for hot-water extracts (PSK is water-soluble). Can be consumed as tea, capsules, or powder.

Cautions

Generally very well tolerated with excellent safety data from decades of clinical use. Mild nausea occasionally reported at high doses. Discuss with oncologist before using during immunotherapy (checkpoint inhibitors) due to immune modulation.