# Turkey tail (Trametes versicolor)

**Trametes versicolor**

**Known today as.** A thin, banded bracket of dead wood, common worldwide.

Kind: Fungus

## What was it used for?

A tea in Chinese and Japanese traditional medicine.

## What does modern science say?

A protein-bound polysaccharide extracted from it, PSK, has been used in Japan since the 1970s alongside chemotherapy for some cancers.

## Pharmacognosy and toxicology

- **polysaccharide-K**: PSK, Krestin
- **polysaccharopeptide**: PSP

**Mechanism.** The protein-bound polysaccharides stimulate immune cells in the dish and in mice.

**Dose.** No toxicity reported.

**Standing.** PSK has been approved in Japan since the 1970s as an adjuvant in gastric and colorectal cancer, with trials showing a modest survival benefit beside chemotherapy; not approved elsewhere.

## What lore surrounds it?

The humblest of brackets, and one of the most studied.

## Sources

- National Cancer Institute, PDQ: Medicinal Mushrooms.
- Oba, K., et al. (2007). “Efficacy of adjuvant immunochemotherapy with polysaccharide K for patients with curative resections of gastric cancer.” *Cancer Immunology, Immunotherapy* 56.

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*Turkey tail.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-09-25. The Thinking Press. https://thethinkingpress.org/materia-medica/turkey-tail

Historical description, not medical advice.