Turkey tail is a woody bracket fungus, Trametes versicolor, that has been used in traditional Chinese medicine for many years. Most of the human research is on a proprietary extract called PSK, an approved mushroom product used in cancer treatment in Japan and given alongside standard treatment in studies. Those studies are mostly in people with cancer and show a modest survival signal in colorectal and stomach cancer, and for healthy adults the human data are limited to immune measures rather than health outcomes.
Turkey tail at a glance
| Item | What the sources say |
|---|---|
| What it is | A woody bracket fungus that grows on dead logs worldwide. Its scientific name is Trametes versicolor, also called Coriolus versicolor. It is known as Yun Zhi in traditional Chinese medicine and Kawaratake in Japan (NCI medicinal mushrooms summary). |
| Forms | Mushroom used in food and tea, and capsules, tablets, powders, tinctures and extracts. The research extracts are PSK and PSP, and VPS is also available as a supplement extract (Memorial Sloan Kettering coriolus page). |
| Doses used in studies | PSK at 3 g per day in the stomach and lung trials cited by the NCI. A rat study used 0.1 to 1.0 g/kg per day. |
| Study length | Four weeks to three years of extract treatment in the seven colorectal trials in the 2022 Cochrane review. One Japanese stomach cancer trial followed patients for five to seven years. |
| Main studied uses | Add-on treatment in stomach, colorectal and lung cancer; immune measures; a vaginal gel for cervical lesions, which is not a capsule. |
| Who was studied | Mostly people with cancer. Six of the seven colorectal trials were in Japan and one in China. |
| Regulatory status in the US | The FDA has not approved the use of medicinal mushrooms as a treatment for cancer or any other medical condition (NCI). Dietary supplements do not need FDA approval before sale unless a disease claim is made. |
What do human studies show about turkey tail?
These are listed strongest first. Most of them used PSK, not a store-bought supplement. For what randomized trials and meta-analyses mean, see ingredient evidence vs marketing claims.
Colorectal cancer: the strongest human evidence
The 2022 Cochrane review pooled seven randomized trials with 1,569 adults who had colorectal cancer and were also getting chemotherapy or radiation. The extract was used in all seven. For five-year survival, the review found a small effect compared with no added treatment: relative risk 1.08 (95% CI 1.01 to 1.15), from 1,094 people in three trials. Its number needed to benefit was 16, and the review rated this finding low certainty. The effect at earlier time points was unclear (2022 Cochrane review of colorectal cancer).
In plain terms, a relative risk of 1.08 is a small relative difference in five-year survival, not a count of extra survivors. The number needed to benefit of 16 is the figure to read for a head count: about one extra person benefited for every 16 people treated.
The NCI also summarizes an earlier meta-analysis of three trials with 1,094 patients, published between 1980 and 2004. It reports five-year survival of 79.0% with chemotherapy plus PSK and 72.2% with chemotherapy alone. Smaller non-randomized Japanese studies also reported better results with PSK.
Stomach cancer: a meta-analysis after surgery
The NCI describes a meta-analysis of eight randomized trials with 8,009 patients who had curative stomach cancer surgery. Patients given chemotherapy plus PSK (4,037) had a lower risk of death than those given chemotherapy alone (3,972). The overall survival hazard ratio was 0.88 (95% CI 0.79 to 0.98; P = .018). A hazard ratio below 1 means fewer deaths over time in the PSK group (NCI medicinal mushrooms summary).
Five-year survival was 67.9% with PSK and 61.8% without (P = .053). In a subgroup with a high granulocyte-to-lymphocyte ratio, survival was 68.7% versus 55.4% (P = .007). The authors suggested that ratio might help predict who responds best, which is a hypothesis rather than a confirmed result. Two retrospective analyses, one from Korea and one from Japan, gave results that contradict each other.
Lung cancer: a systematic review with mixed trial designs
The NCI reviewed 28 studies of PSK in lung cancer: 17 laboratory studies, five non-randomized controlled trials and six randomized trials. All five non-randomized trials reported improved median survival when PSK was added to radiation or chemotherapy. All six randomized trials used PSK at 3 g per day with chemotherapy, and each showed benefit on at least one measure: immune function, body weight, performance status, tumor-related symptoms or survival. The benefits were not on the same measures in every trial.
The Memorial Sloan Kettering coriolus page reports that a PSP extract given with chemotherapy suggests benefits in advanced non-small cell lung cancer, and that patients had higher leukocyte and neutrophil counts and higher serum IgG and IgM after taking it.
Breast cancer: immune measures, not survival
The NCI says studies of turkey tail in breast cancer have focused on immune measures, such as changes in T-cell subsets and B-cell numbers, rather than survival, symptoms or quality of life. The Memorial Sloan Kettering page describes the breast cancer data as mixed.
Immune changes in healthy adults and people with breast cancer
Memorial Sloan Kettering reports that healthy volunteers and breast cancer patients who used a formula combining Coriolus and Salvia had higher CD4+ counts, a higher CD4+/CD8+ ratio and higher B-lymphocyte counts. The healthy-volunteer work was a randomized, double-blind, placebo-controlled, crossover study. The same page reports that TNF-alpha and IL-8 gene expression rose after PSK in healthy volunteers and gastric cancer patients, though individual responses varied (Memorial Sloan Kettering coriolus page).
Liver cancer
Memorial Sloan Kettering says the data on turkey tail in liver cancer are mixed. It cites a 2017 study of Coriolus versicolor in people with advanced liver cancer who had poor liver function or were unfit for standard therapy. There is no established liver benefit from turkey tail in these sources.
Other cancers
Memorial Sloan Kettering says PSK appears to improve survival in gastric and colorectal cancers and may benefit esophageal cancer. It describes leukemia data as mixed, and reports a meta-analysis that found reduced mortality with adjuvant use across several cancers, while noting that confirmatory studies are needed.
Cervical lesions: a vaginal gel, not a supplement
Memorial Sloan Kettering says a coriolus-based vaginal gel had clinical benefits in women with HPV-related low-grade cervical lesions. It cites the PALOMA study (2021), the Papilobs real-life prospective study (2023) and a 2026 scoping review. The Papilobs title describes a multi-ingredient gel. These studies test a gel used in the cervix area, so they do not describe what a capsule does. If you are considering a gel for cervical changes, talk with the clinician who manages your care.
Lab and animal studies (not human evidence)
A 2020 rat study gave an extract of fermented turkey tail polysaccharopeptides by mouth to male rats with type 2 diabetes for four weeks (rat study of fermented turkey tail extract). At 0.1, 0.5 and 1.0 g/kg per day, rises in blood glucose, fructosamine and triglycerides were blunted in a dose-dependent way, and markers of oxidative stress improved. The authors suggested this may help prevent diabetic complications in people with type 2 diabetes.
A 2019 lab study tested mycelium and fermented substrate on human immune cells in culture (mycelium immune study). In that study, both the water and solid fractions of the mycelium activated lymphocytes and monocytes, with the water fraction stronger than the solid fraction. The fermented substrate produced large cytokine increases. The study was in cultured cells, not people.
A 2020 analysis of a wild turkey tail mushroom measured amino acids, phenolic compounds and antioxidant activity. The authors said it supports potential use as a source of bioactive products (composition and antioxidant study).
What doses were used in studies?
| Use studied | Form | Dose used |
|---|---|---|
| Stomach cancer after surgery, Japanese trials (NCI) | PSK with chemotherapy | 3 g per day |
| Lung cancer, six randomized trials (NCI) | PSK with concurrent chemotherapy | 3 g per day |
| Colorectal cancer meta-analysis (NCI) | PSK with chemotherapy | Various doses across trials |
| Rats with type 2 diabetes (PubMed) | Fermented extract given by mouth | 0.1, 0.5 or 1.0 g/kg per day for 4 weeks |
These are the amounts researchers used. They are not a recommendation, and a supplement label may list a different form and amount. Memorial Sloan Kettering notes that herbal supplements are stronger than the herbs used in cooking, which is one reason it advises talking with a provider before taking capsules.
Is turkey tail safe, and what are the side effects?
The NCI says the safety record for PSK is well established in Japan, with few adverse events reported in patients treated with it. Memorial Sloan Kettering says coriolus extracts are generally well tolerated but minor adverse effects have been reported. The 2022 Cochrane review was uncertain about side effects overall.
| Effect | What the source says |
|---|---|
| Dark-colored stools | Listed as a side effect of coriolus, and described as rare when not caused by blood in the stool (Memorial Sloan Kettering). |
| Darkened fingernails | Listed as a side effect and as a rare adverse reaction (Memorial Sloan Kettering). |
| Low blood-count and digestive effects | Described as rare when used with chemotherapy. Memorial Sloan Kettering says these may be caused by the chemotherapy agents themselves. |
| Nausea, diarrhea, fatigue, mouth dryness or sores | The Cochrane review found no clear difference for these with the extract, but the authors were uncertain and rated the evidence very low certainty. |
| Low neutrophil counts (neutropenia) | One analysis of 133 people in three trials found a lower rate with the extract (RR 0.41, 95% CI 0.24 to 0.71), rated very low certainty. |
| Stopping treatment because of side effects | RR 1.03 (95% CI 0.45 to 2.34) across 703 people in three studies, rated very low certainty, with little to no difference reported. |
Memorial Sloan Kettering also reports a mouse study in which high doses of a hot-water extract of Coriolus increased intestinal tumors. It says this is not clinically relevant, because the dose was 10 to 13 times higher than in human studies and the mice were given known potent carcinogens.
What not to mix with turkey tail
Memorial Sloan Kettering says coriolus can interact with some medications and affect how they work, and it asks people to tell their providers about every supplement, herb or home remedy they take. In the trials, the extract was added to chemotherapy or radiation rather than used in place of it. The Cochrane authors noted it was unclear whether side effects came from the chemotherapy or from the extract. Bring your full medicine list to your clinician before you start.
Is turkey tail hard on the liver?
The side effects Memorial Sloan Kettering lists are dark stools, darkened fingernails and, with chemotherapy, blood-count and digestive effects. Liver injury is not on that list. The liver cancer research it cites involved people with poor liver function, and it calls that data mixed. If you have liver disease or take medicines that affect the liver, ask your clinician before using it.
Who should talk to a clinician first?
- Anyone who is pregnant or breastfeeding. Memorial Sloan Kettering says pregnant or breastfeeding women should avoid coriolus until safety data become available.
- Anyone in cancer treatment or preparing for it. The studies gave the extract alongside chemotherapy or radiation, and the same page advises talking with providers before taking supplements.
- Anyone taking any prescribed or over-the-counter medicine, because coriolus can interact with some medications.
- Anyone considering it instead of standard cancer care. The FDA has not approved medicinal mushrooms for cancer treatment, and the studies used it alongside standard treatment.
- Anyone with cervical changes who is considering the vaginal gel.
Bring the product label to the appointment so your clinician can check the form and amount.
What is still unknown?
Most cancer studies used PSK, a proprietary research extract, and not whole mushroom powders or store supplements. Memorial Sloan Kettering says it is unclear whether PSK, PSP and other coriolus extracts have comparable effects. The certainty of the colorectal survival finding is low, and the side-effect findings are very low certainty. Many of the trials are older, and the Cochrane authors note that their chemotherapy regimens do not reflect current preferred practice. The immune studies measure immune markers, not health outcomes, and the rat and lab studies do not show what happens in people. Memorial Sloan Kettering says many over-the-counter products are not standardized, which makes potency hard to compare between brands. The NCI notes that supplement ingredients may vary from lot to lot and that labelled ingredients are not guaranteed to be present in the stated amounts. How turkey tail works in the body is not fully settled; Memorial Sloan Kettering describes it as thought to be a biological response modifier. Whether daily use over years is safe has not been established.
On skin: Memorial Sloan Kettering lists turkey tail’s uses as improving general health and boosting the immune system, and skin is not among them. For a skin goal, a dermatologist can tell you which options have evidence behind them. On men and women: five of the seven colorectal trials included both men and women. Women-specific research covers breast cancer studies as well as the cervical gel studies.
How do you read a label that lists turkey tail?
- Names: Trametes versicolor and Coriolus versicolor are the scientific names. PSK, PSP and VPS are the extract names Memorial Sloan Kettering lists.
- Amount: look for milligrams or grams per serving. The studies used PSK at 3 g per day, so a small listed amount is not the same thing as a study dose.
- Form: fruiting body, mycelium or fermented substrate. A 2019 lab study found the mycelium and fermented substrate had different immune-activating effects in cultured human cells, and no human study cited here compares these forms.
- Standardization: Memorial Sloan Kettering says many over-the-counter products are not standardized.
- Blends: if turkey tail is one of several mushrooms, look for the amount of each ingredient. A single total for a proprietary blend does not show how much turkey tail you get.
- Beta-glucan figures: a general polysaccharides number can overstate beta-glucans, so look for a test that measures beta-glucans specifically, as the Vita Globe article’s guidance advises.
- Lot variation: ingredients can vary between batches, as the NCI notes.
For the same questions about another extract, see turmeric and curcumin.
By ClinicalStudyConnect.com Research Desk
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.