Turkey Tail: PSK, PSP and the Most Researched Functional Mushroom in the World
Turkey Tail (Trametes versicolor) is the most scientifically studied functional mushroom, known for its unique polysaccharopeptides PSK and PSP. Learn about its bioactive compounds, traditional use, and what makes it the benchmark for mushroom research.
Turkey Tail (Trametes versicolor): PSK, PSP and the Most Researched Functional Mushroom
Turkey Tail (Trametes versicolor, formerly Coriolus versicolor) is arguably the most scientifically studied functional mushroom in the world. Named for its striking fan-shaped fruiting bodies with concentric rings of colour resembling a wild turkey's tail feathers, it grows on dead and decaying hardwood trees across forests worldwide — making it one of the most abundant and widely distributed wood-decay fungi on Earth.
Important regulatory note: Turkey Tail (Trametes versicolor) is classified as a novel food in the European Union under Regulation (EU) 2015/2283. This means it has not yet received authorisation for general sale as a food ingredient in the EU. Nutera's Turkey Tail product is sold as a food supplement in accordance with applicable regulations.
The Key Bioactive Compounds: PSK and PSP
Turkey Tail's scientific distinction rests primarily on two unique polysaccharopeptides:
PSK (Polysaccharide-K / Krestin)
PSK (also known as Krestin) is a protein-bound polysaccharide isolated from the CM-101 strain of Trametes versicolor. It consists of a beta-glucan backbone with protein side chains. PSK has been approved in Japan since 1977 as an adjunct in oncology settings and is one of the best-selling pharmaceutical products in Japan.
PSP (Polysaccharide Peptide)
PSP is a closely related but distinct polysaccharopeptide isolated from the COV-1 strain of Trametes versicolor. It was developed primarily in China and has been the subject of extensive clinical research there.
Both PSK and PSP are water-soluble and are therefore captured by hot water extraction — the standard method for Turkey Tail processing.
Beta-Glucans
Turkey Tail is exceptionally rich in (1→3),(1→6)-β-D-glucans, which form the backbone of both PSK and PSP. These are the primary quality markers in standardised extracts.
Phenolic Compounds
Turkey Tail contains a diverse array of phenolic compounds, including flavonoids (quercetin, baicalein, kaempferol) and phenolic acids (caffeic acid, gallic acid, chlorogenic acid). These contribute to its antioxidant activity.
Bioactive Compounds at a Glance
| Compound | Type | Notes |
|---|---|---|
| PSK (Krestin) | Polysaccharopeptide | Approved pharmaceutical in Japan |
| PSP | Polysaccharopeptide | Developed in China |
| (1→3),(1→6)-β-D-glucans | Polysaccharides | Primary quality marker |
| Quercetin | Flavonoid | Antioxidant |
| Caffeic acid | Phenolic acid | Antioxidant |
Traditional Use
Turkey Tail has been used in Traditional Chinese Medicine (Yún Zhī — 云芝, "cloud mushroom") and Japanese Kampo medicine for centuries as a general tonic. It was traditionally prepared as a tea and consumed for vitality and as a seasonal tonic.
Quality Markers
- Fruiting body — not mycelium-on-grain (which lacks PSK/PSP)
- Hot water extraction — essential to capture water-soluble polysaccharopeptides
- Polysaccharide standardisation — ≥30% is the benchmark
- Colour verification — authentic Turkey Tail has distinctive multicoloured concentric rings
This article is for informational purposes only. Food supplements are not intended to diagnose, treat, cure, or prevent any disease. Turkey Tail (Trametes versicolor) is a novel food in the EU.
— Products mentioned in this article
