Turkey Tail (Trametes versicolor)
Turkey tail is the one functional mushroom with genuinely strong clinical evidence — but its reputation is widely misunderstood. The evidence is for a specific, standardised pharmaceutical preparation used under medical supervision, not for the capsule on a health-shop shelf.
Not medical advice. Nothing here is a treatment for cancer or any disease. If you are undergoing cancer treatment, discuss any supplement with your oncologist first.
What the evidence shows
Turkey tail's active agents are the standardised polysaccharide fractions PSK (Krestin) and PSP. As an adjunct to surgery and chemotherapy — mainly in Japan and China — these have randomised-trial and meta-analysis support, including improved survival in some gastric and colorectal cancer studies. Crucially, this is hospital-grade, oncologist-supervised therapy using a defined, standardised product. It is not the same as an over-the-counter turkey tail capsule, which is not standardised, and it is not a cancer cure or preventive.
Evidence level: clinical, as a supervised oncology adjunct.
How it's used
Fruiting-body extract powder, capsules and tincture for the retail product; the studied PSK/PSP are a distinct, standardised pharmaceutical class.
Safety
Generally well tolerated; darkened stool or nails have been reported. Because it is immune-modulating, use caution with immunosuppressant medication (transplant or autoimmune conditions). Avoid in pregnancy and breastfeeding (no safety data).
Quality notes
As with all functional mushrooms, look for fruiting-body products that publish a measured beta-glucan percentage and a third-party COA, rather than mycelium-on-grain powders or vague "polysaccharide" figures.
Sources
- Turkey tail (PSK) adjuvant RCT — Nakazato, Lancet 1994.
- Memorial Sloan Kettering, About Herbs — Coriolus versicolor (turkey tail).
- Systematic review of adjuvant Coriolus — Front Pharmacol 2019.
Explore the other medicinal mushrooms or our full plant catalogue.