Turkey tail (Trametes versicolor / PSK)
Polysaccharide-K (PSK) and PSP, Japanese-approved adjuvant in gastric and colorectal cancer treatment; outside oncology, immune-modulating evidence is preliminary.
Why
Turkey tail (Trametes versicolor, formerly Coriolus versicolor) yields two extensively-studied polysaccharide-protein extracts: PSK (krestin), approved in Japan as a cancer adjuvant alongside chemotherapy for gastric and colorectal cancer, and PSP (polysaccharide peptide) used similarly in China. The Oba 2007 meta-analysis of PSK adjuvant therapy reported improved overall survival in colorectal cancer. Outside oncology, general immune-modulating use has preliminary but smaller evidence. Cancer-adjuvant use must be under oncologist supervision, not for self-management.
How it works
PSK and PSP are protein-bound β-glucans that bind toll-like receptors (TLR-2, TLR-4) and Dectin-1 on innate immune cells, increasing NK cell and macrophage activity. Independent effects on T-cell function and cytokine balance.
Expected onset · Oncology endpoints over months-years; general immune markers over weeks
How to take
Dosage
PSK (Krestin): 1–3 g/day in clinical adjuvant trials. PSP: similar. Generic turkey tail mushroom extract: 1–3 g/day dual extract.
Timing
Divided 2–3 times daily with food
On the label
Dual-extract (hot water + ethanol) Trametes versicolor (turkey tail) with stated β-glucan and triterpene content. Avoid mycelium-on-grain products which are mostly grain.
Ideal for
Cancer patients (gastric, colorectal) considering adjuvant approaches alongside conventional treatment, under oncology supervision, Japan-approved indication. General immune-support use outside oncology context is preliminary.
Safety
Evidence
Oba 2007 meta-analysis (eight Japanese RCTs, n=8,009 colorectal): PSK as adjuvant to chemotherapy reduced mortality risk by 28% over 5 years. Sakamoto 2006 meta-analysis for gastric cancer showed similar adjuvant benefit. PSK has been a clinically-prescribed adjuvant in Japan since 1977, among the most-evidenced 'mushroom' supplements in oncology contexts, but use must be physician-supervised.
- Oba et al., Cancer Immunol Immunother 2007, efficacy of adjuvant immunochemotherapy with polysaccharide-K for patients with curatively resected colorectal cancer: meta-analysis
- Sakamoto et al., Cancer Immunol Immunother 2006, efficacy of adjuvant immunochemotherapy with polysaccharide-K for patients with curatively resected gastric cancer: meta-analysis
- Torkelson et al., ISRN Oncol 2012, phase 2 study of Trametes versicolor mushroom in patients with breast cancer
Where to get it
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