Lentinan is a purified beta-glucan taken from the shiitake mushroom (Lentinula edodes). It is not the same thing as eating shiitake or taking a shiitake supplement. Lentinan is a specific, lab-purified compound that has been studied and used in Japan as an add-on to chemotherapy, mainly for stomach cancer. It is not approved as a cancer treatment in the United States.
Read This Before Anything Else
Lentinan has only ever been studied as an add-on to standard cancer treatment, never as a replacement for it. No one should stop, delay, or change chemotherapy, radiation, or any prescribed cancer treatment based on shiitake, beta-glucan supplements, or anything in this article. Decisions about cancer treatment belong to the patient and their oncology team.
Two other things matter before you read further:
- The lentinan used in research is typically given by injection, not swallowed as a capsule or powder. This is a critical difference from shiitake supplements sold in stores, covered below.
- Lentinan may interact with certain medications. One documented interaction involves zidovudine (AZT), an HIV medication, according to Memorial Sloan Kettering Cancer Center’s integrative medicine database. Anyone taking prescription medication should talk with a doctor or pharmacist before adding any mushroom-derived supplement.
How Lentinan Differs From Ordinary Shiitake Beta-Glucans
Shiitake mushrooms naturally contain beta-glucans, a type of polysaccharide (complex carbohydrate) found in the cell walls of many mushroom species. Our guide to mushroom beta-glucans covers this compound family across species. Lentinan is a specific, highly purified form of shiitake beta-glucan, isolated and standardized for research and clinical use in Japan.
This purification matters because of how the body absorbs it. According to research summarized on this site’s own beta-glucans page, lentinan “is thought to be inactive in humans when given orally and is therefore administered intravenously.” In plain terms: the lentinan studied in cancer research is delivered by IV infusion in a clinical setting. Eating shiitake mushrooms or swallowing a shiitake supplement capsule is a completely different exposure, and researchers have not shown that oral shiitake products deliver the same effect.
Our existing shiitake mushroom research and safety guide makes the same point directly: research on lentinan as a clinical adjunct “cannot be transferred to retail powders or gummies.”
What Human Clinical Research Actually Shows
Lentinan has a real body of human clinical research behind it, almost entirely from Japan and China, mostly in people with gastric (stomach) cancer receiving chemotherapy. Here is what that research shows, separated from mechanism and animal data.
- Gastric cancer, survival: A meta-analysis cited in a peer-reviewed review found that adding lentinan to chemotherapy extended survival in patients with advanced gastric cancer, with a reported difference of 139 days versus 114 days (a modest but statistically noted difference).
- Gastric cancer, retrospective cohort: A retrospective study of 78 patients receiving S-1-based chemotherapy reported longer median overall survival with lentinan added (689 days) compared to chemotherapy alone (565 days), and a higher five-year survival rate (10.0% versus 0%). This is one retrospective study, not a large randomized trial, so it should be read as suggestive rather than definitive.
- Broader cancer types: According to Memorial Sloan Kettering Cancer Center, clinical trials have combined lentinan with chemotherapy in stomach, prostate, colorectal, and liver cancers, and separately studied it in esophageal and non-small cell lung cancer. Survival extension has been reported in the stomach, prostate, colorectal, and liver cancer trials; quality-of-life improvements have been reported in the esophageal and lung cancer studies.
- Federal government summary: The National Cancer Institute’s overview of mushroom polysaccharides notes that “medicinal mushrooms have been approved adjuncts to standard cancer treatments in Japan and China for more than 30 years,” while also stating plainly that “the FDA has not approved the use of medicinal mushrooms as a treatment for cancer or any other medical condition” in the United States.
Every one of these findings describes lentinan used alongside chemotherapy, not instead of it, and the strongest data is limited to a small number of cancer types studied mainly in one country.
Mechanism: What Preclinical Research Suggests (Not Proof of Effect in People)
Laboratory and animal research offers a possible explanation for why lentinan might help, but this is mechanistic evidence, not proof that it treats cancer on its own. According to a review published on PubMed Central, lentinan is believed to work by:
- Binding to immune cell receptors (including Dectin-1 and complement receptor 3) on macrophages, dendritic cells, and natural killer cells
- Triggering production of immune signaling molecules such as IL-12 and TNF-alpha
- Boosting the immune system’s ability to target and clear abnormal cells (a process called antibody-dependent cellular cytotoxicity)
This is described as immune stimulation, not direct tumor killing. Lentinan is classified as a “biological response modifier,” meaning it is thought to support the body’s own immune response rather than act as a chemotherapy drug itself.
Why Japan Approved Lentinan and Western Regulators Have Not
Japan and China have allowed medicinal mushroom-derived compounds, including lentinan, as adjunct cancer therapies for over three decades, according to the National Cancer Institute. Several factors explain why that has not carried over to the United States:
- Different evidentiary bar. Japan’s regulatory pathway for this category of biological response modifiers has historically accepted a different standard of trial evidence than the FDA requires for cancer drug approval.
- Trial design and age. Much of the supporting research is older, conducted in the 1980s and 1990s using chemotherapy regimens that are no longer standard of care, which limits how well the findings apply to modern cancer treatment.
- Limited modern data. There is little published research on lentinan combined with newer targeted cancer therapies, such as trastuzumab, that are now standard in many gastric cancer treatment plans.
- Delivery route. Because lentinan appears inactive when taken orally, any US approval pathway would require an injectable pharmaceutical product tested to FDA standards, not a dietary supplement, which is a much longer and more expensive process.
- No FDA-approved use exists. The National Cancer Institute states directly that the FDA has not approved medicinal mushrooms, including shiitake-derived compounds, as a cancer treatment.
Pharmaceutical-Grade Lentinan vs. Dietary Shiitake Supplements: A Decision Path
Because these two things are easy to confuse, use this checklist to sort out what you may be looking at:
- Is it given by injection in a clinical or hospital setting, as part of a Japanese cancer treatment protocol? That is pharmaceutical-grade lentinan, the form studied in the clinical trials above.
- Is it a capsule, powder, tincture, or gummy sold as a dietary supplement in the US? That is not the same product. It has not been shown to deliver the same dose or the same effect, since lentinan appears to be inactive when taken by mouth.
- Is it whole shiitake mushrooms eaten as food? Shiitake is a nutritious food with its own general immune-function research, but eating shiitake has not been studied as a cancer therapy and should not be treated as one.
- Is a supplement label claiming it “fights cancer” or “boosts your immune system” using the word lentinan? Treat that claim with skepticism. No dietary supplement sold in the US has been FDA-approved to treat, prevent, or cure cancer, and label language cannot substitute for a conversation with an oncologist.
Who Should Use Extra Caution
- Anyone currently in active cancer treatment should discuss any mushroom-derived supplement with their oncology team first, since even food-form supplements can interact with treatment or complicate side-effect tracking.
- People taking zidovudine (AZT) or other antiretroviral medications should ask a doctor or pharmacist before using lentinan or shiitake-derived supplements, given the documented interaction noted by Memorial Sloan Kettering Cancer Center.
- People with known mushroom allergies or a history of shiitake dermatitis (a skin rash linked to eating shiitake) should be cautious with any shiitake-derived product.
- Anyone considering an infusion-based lentinan product from outside the United States should understand it is not FDA-regulated and should only be pursued, if at all, under the guidance of a licensed oncologist.
See our full mushroom safety and interactions guide for broader precautions across mushroom species and compounds.
Evidence Limits
Readers should understand what this research does and does not show:
- Most human trials come from Japan and China, using patient populations, healthcare systems, and chemotherapy regimens that may differ from current US standard of care.
- Several key studies are decades old and have not been repeated with modern treatment combinations.
- No study has shown lentinan cures cancer, shrinks tumors on its own, or replaces chemotherapy, radiation, or surgery.
- No research supports oral shiitake supplements producing the same effects seen with injectable lentinan in these trials.
- Sample sizes in several of the most specific studies (such as the 78-patient retrospective cohort) are small, which limits how confidently the results can be generalized.
Frequently Asked Questions
Is eating shiitake mushrooms the same as taking lentinan?
No. Lentinan is a purified, injectable compound studied in clinical settings. Eating shiitake mushrooms provides beta-glucans and other nutrients as part of a normal diet, but has not been studied as a cancer treatment and delivers a very different exposure than clinical-grade lentinan.
Is lentinan approved as a cancer treatment in the United States?
No. The FDA has not approved lentinan or any medicinal mushroom compound as a cancer treatment. Lentinan’s adjunct-therapy approval exists in Japan, primarily for gastric cancer, alongside standard chemotherapy.
Can lentinan replace chemotherapy or other cancer treatment?
No. Every clinical trial reviewed here studied lentinan as an addition to chemotherapy, not as a stand-alone treatment. No qualified source supports using it, or any mushroom supplement, in place of prescribed cancer treatment.
Do shiitake supplements sold online contain the same lentinan used in research?
Not in a form shown to work the same way. Research-grade lentinan is typically given by IV infusion, and available evidence suggests it is inactive when taken orally. Oral shiitake supplements have not been shown to reproduce the effects seen in the injectable clinical studies described above.
Educational Disclaimer
This article is for general education about mushroom-derived compounds and published research. It is not medical advice and does not diagnose, treat, cure, or prevent any disease. It is not a recommendation to use, start, stop, or change any supplement or cancer treatment. Anyone with a cancer diagnosis, or considering any supplement alongside cancer treatment, should talk with a qualified oncologist or physician first.