Two mushrooms, turkey tail and reishi, have real human clinical trial data behind them as adjunctive support alongside standard cancer treatment, not as cures. No mushroom, mushroom extract, or mushroom supplement is approved by the FDA to treat, cure, or prevent any cancer. The clinical trials that exist studied specific isolated compounds given alongside chemotherapy in supervised settings, not the over-the-counter capsules and powders sold as general supplements.
This page separates what human trials found from what only lab and animal studies found, and explains why that difference matters before anyone with cancer adds a mushroom product to their care.
Read This Before Anything Else
If you or someone you love has cancer, do not start, stop, replace, or adjust any treatment based on a mushroom supplement. Tell the full oncology care team about any mushroom product before taking it, including the brand, dose, and how often. Some products can interact with chemotherapy, radiation, or immunotherapy, and those interactions have not been well studied for most over-the-counter products.
The National Cancer Institute is direct about this: “there are no studies that prove that any special diet, food, vitamin, mineral, dietary supplement, herb, or combination of these can slow cancer, cure it, or keep it from coming back.” That statement covers mushroom supplements too.
Adjunctive Research vs. Cancer Treatment
“Adjunctive” means used alongside standard treatment, not instead of it. The clinical trials behind turkey tail and reishi tested mushroom-derived compounds given in addition to chemotherapy or surgery, in patients who were already receiving standard care. None of the trials tested mushrooms as a replacement for chemotherapy, radiation, surgery, or approved drugs.
This distinction matters because a compound that shows a benefit when added to chemotherapy is not the same as a compound that treats cancer on its own. The research doesn’t support the second claim, only the first, and only for specific isolated compounds studied in specific cancer types.
Species With the Most Human Clinical Evidence
Most mushroom and cancer research is still preclinical: cell studies in a lab, or trials in mice. Only a small number of species have been tested in human clinical trials for cancer-related outcomes, and turkey tail has by far the strongest track record.
Turkey Tail (PSK)
PSK, a polysaccharide compound from turkey tail, has been given alongside chemotherapy in randomized human trials for gastric, colorectal, and lung cancer. Reviews of these trials found that patients receiving PSK plus chemotherapy tended to live longer than those on chemotherapy alone, and in colorectal cancer, PSK recipients were less likely to have the cancer come back. The key limit: these trials used a standardized, isolated PSK extract, not the turkey tail powders or capsules sold as general supplements.
Reishi (Ganoderma lucidum)
Evidence is more limited and mixed than turkey tail. Studies in lung cancer patients looked at immune markers, with some showing changes in immune cell activity and others showing none. One study of 225 people found fewer and smaller colorectal polyps in the group taking reishi. Most reishi trials did not measure survival, and a 2025 systematic review of reishi research overall rated the certainty of the evidence as very low.
Shiitake, Maitake, and Other Species
These are mostly supported by lab and animal studies of immune cell activity and tumor growth in mice. There is no substantial human clinical trial data specific to cancer outcomes for these species.
For a closer look at each species individually, see the turkey tail research profile and the reishi research profile.
Human Evidence vs. Preclinical Evidence: Know the Difference
Headlines about “mushrooms and cancer” often blend together very different kinds of evidence. Here’s how to tell them apart before trusting a claim.
- Human clinical trials: Studies in actual cancer patients, ideally randomized and compared to a control group. This is the only evidence type that can support a claim about what happens in people.
- Animal studies: Research in mice or rats. These can point toward ideas worth testing in humans, but effects in animals often don’t repeat in people.
- In-vitro (lab dish) studies: Mushroom compounds applied directly to cancer cells in a petri dish. This is early-stage science, several steps removed from how a supplement behaves in a human body.
- Mechanistic studies: Research explaining how a compound might work at the cellular level, without proving it works in a whole person.
- Traditional or historical use: Mushrooms used in traditional medicine for centuries. This shows a long history of use, not proof of a cancer benefit.
Most of what circulates online about “mushrooms curing cancer” comes from the last three categories, not human clinical trials. Our full breakdown of how these evidence types rank against each other is in the evidence hierarchy guide.
Why an Over-the-Counter Supplement Is Not the Same as the Study
Even where human trials exist, the product on a store shelf is usually not the same as what was tested. The clinical trials behind PSK used a standardized, pharmaceutical-grade extract manufactured under strict quality control. Dietary supplements are regulated differently.
The FDA does not approve dietary supplements before they go on sale, and it does not routinely test batches for potency or purity. That means one brand’s turkey tail capsule may contain a very different amount of active compound than another brand, or than the extract used in a clinical trial. The FDA has also stated plainly that it has not approved turkey tail, PSK, reishi, or any mushroom product as a treatment for cancer or any other medical condition.
Who Needs Extra Caution
- Anyone currently in cancer treatment: chemotherapy, radiation, immunotherapy, and surgery can all interact with supplements in ways that haven’t been studied for most over-the-counter mushroom products. Disclose everything to the oncology team first.
- People with a mushroom or mold allergy: mushroom supplements can trigger allergic reactions.
- People taking immune-suppressing medication: some mushroom compounds may affect immune activity, so this should be discussed with the prescribing doctor.
- Anyone scheduled for surgery: tell the surgical team about any supplement in advance.
- Pregnant or breastfeeding people: cancer-related mushroom research has not studied safety in pregnancy or breastfeeding.
General interaction and safety information for mushroom supplements overall is covered in the mushroom safety and interactions guide.
A Decision Path Before Trying Any Mushroom Product During Cancer Care
- Ask: is the goal to support well-being during standard treatment, or to replace a treatment? If it’s to replace treatment, stop and talk to the oncology team first — no mushroom product is a proven substitute for standard cancer care.
- Bring the exact product name, brand, and label to the oncology team before starting it.
- Ask the care team directly whether it could interact with the specific chemotherapy, radiation, or other drugs being used.
- Check whether the product lists a standardized extract (like PSK) or is a general mushroom powder — these are not equivalent, and only the former has clinical trial data behind it.
- Keep the care team updated if the product is continued, changed, or stopped.
Frequently Asked Questions
Can turkey tail or reishi mushrooms cure cancer?
No. No mushroom or mushroom supplement is proven to cure cancer, and none is FDA-approved as a cancer treatment. The clinical trials that exist looked at specific compounds used alongside standard treatment, not as a replacement for it.
Is PSK from turkey tail an approved cancer drug?
PSK has been studied in multiple human clinical trials alongside chemotherapy, with a long history of use in Japan. It is not FDA-approved as a cancer treatment in the United States.
Is it safe to take mushroom supplements during chemotherapy?
This depends on the specific product, the specific treatment, and the individual’s health situation, and it has not been well studied for most over-the-counter products. Anyone in cancer treatment should talk to their oncology team before starting a mushroom supplement.
Why do some mushroom products claim strong cancer benefits if the research is limited?
Marketing claims often draw on lab or animal studies, or historical use, and present them as if they were confirmed in human trials. Checking whether a claim is backed by a human clinical trial, and whether that trial used the same product being sold, is the best way to evaluate these claims.
Educational Disclaimer
This article is for general education only. It is not medical advice and does not diagnose, treat, or replace guidance from a qualified oncologist or healthcare provider. Anyone with cancer, or anyone considering a mushroom supplement during cancer treatment, should talk with their care team before starting, stopping, or changing anything.