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Shiitake, Lentinan and Immune Research: Food vs Extract

Shiitake (Lentinula edodes) as food, as a supplement, and as lentinan, an injected cancer-care medicine in Japan and China. What trials found, shiitake rash, and what is not established.

Content last updated . This page has not been medically reviewed.

Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.

Three different things share one name

  • Shiitake as food: the fresh or dried mushroom, Lentinula edodes (GBIF lists it as an accepted species in the family Omphalotaceae). [7] The full profile is on the shiitake guide.
  • Shiitake supplements: powders and extracts of the mushroom, sold as dietary supplements.
  • Lentinan: a purified beta-glucan polysaccharide extracted from shiitake, used as an injected medicine alongside chemotherapy. Reviews say it is approved as an adjunct to chemotherapy in China and Japan. [8]

These are not interchangeable. The monograph states that most studies of lentinan involve intravenous or intramuscular injections and that it is uncertain whether eating shiitake provides similar effects. [9]

Traditional use

A review of lentinan notes that shiitake has been recorded in Chinese medicine to "nourish the blood and qi". [10] That is traditional use only. See PSK, PSP and lentinan.

What research shows

QuestionWhat the source foundStrength of evidenceForm, population and amount studied
Injected lentinan with chemotherapy, advanced gastric cancer (pooled patient data)Survival hazard ratio 0.80 (0.68 to 0.95) favoring lentinan. [11]Promising but limited (older trials)Injected lentinan; 650 patients from 5 randomized trials
Same, newer randomized trial (S-1 chemotherapy)The authors concluded the study showed no efficacy of lentinan added to S-1 in this group; median survival 13.8 months with S-1 alone vs 9.9 with lentinan added, P = 0.208. [12] [13]Mixed against the pooled result309 patients with unresectable or recurrent gastric cancer
Injectable lentinan with chemotherapy, gastric cancer (2024 meta-analysis)Better treatment efficacy and quality-of-life scores; no serious adverse effects observed; the authors say more trials are needed. [14]Promising but limited31 randomized trials, 2,729 patients; injection
Shiitake extract in prostate cancerOne clinical trial showed that a shiitake extract alone was not effective. [15]No good evidence of benefitExtract, one trial
Shiitake beta-glucan mixture, cholesterol and immunityNo significant differences in cholesterol-related parameters or inflammatory markers vs placebo after 8 weeks. [16] [17]No good evidence of benefit in this trial52 adults with mild high cholesterol; mixture from shiitake
Fungal beta-glucans, all sources, immune outcomesA review of 34 randomized trials found immune findings inconsistent at the cellular and molecular level. [18] [19]MixedShiitake was one of five sources; not specific to shiitake food

Two points matter for readers. First, the best-studied results are for injected lentinan given by clinicians with chemotherapy, and they should not be applied to eating shiitake or taking a capsule. Second, results across trials disagree, so treat the gastric cancer evidence as contested, not settled. The monograph also describes lentinan as a biological response modifier that, in laboratory tests, enhances immune function rather than killing cancer cells directly. [20] That is a laboratory finding, not a human outcome.

Shiitake and "immune support"

Proper evidence not found for a trial that tests shiitake food or capsules on infections or disease in people. We searched PubMed for Lentinula edodes randomized trials and read the monograph and the fungal beta-glucan review above, which mixes several fungal sources. For the wider picture see mushrooms and immune function.

Official statements

Reviews state lentinan is approved as an adjuvant cancer drug in China and Japan. [22] We did not read a statement from a regulator on shiitake supplements and so make no claim about one.

Frequently asked questions

Is shiitake good for the immune system?

Not established. Lab studies suggest immune effects, but human trials of fungal beta-glucans were inconsistent. [19] A shiitake extract trial found no immune or cholesterol changes. [17]

What is lentinan?

A purified polysaccharide from shiitake, approved as an adjunct to chemotherapy in China and Japan, mostly studied as an injection. [8] [9]

Can shiitake treat cancer?

No. Injected lentinan has been studied with chemotherapy and the trials disagree; [11] [12] a shiitake extract alone was not effective for prostate cancer. [15]

Why did I get a rash after eating shiitake?

Shiitake dermatitis is a recognized reaction, linked to raw or undercooked shiitake. [1] It resolved completely in the cases reviewed. [3] See a clinician if it is severe.

Is shiitake safe to eat?

For most people shiitake is an ordinary food, but undercooked shiitake can cause the rash above, and eating a whole mushroom has been linked to small bowel obstruction. [6]

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

Safety first: shiitake rash and undercooked shiitake
Shiitake dermatitis is a documented reaction: an itchy rash of linear, whip-like streaks. A review of cases reported to French poison centers found 59 cases of dermatitis among 125 shiitake exposures, all after raw or undercooked shiitake, with the rash appearing a median of 48 hours later and lasting a median of 10 days. [1] [2] All patients recovered completely. [3] The mechanism is thought to involve lentinan, a heat-labile polysaccharide, and the authors point to inadequate cooking as a driver. [4] A cancer-center monograph also lists increased skin sensitivity to sunlight and upset stomach, [5] and small bowel obstruction from eating a whole shiitake mushroom. [6] See cooking edible mushrooms safely. If a rash is severe, or breathing or swelling is affected, get medical care; call 911 for severe symptoms.
Safety for specific groups
  • Cancer care: lentinan injection is given by a clinical team. Tell the oncology team about any shiitake extract or supplement. See mushrooms and cancer claims.
  • Medicines, pregnancy, breastfeeding, children, liver and kidney disease, surgery: not described in the sources we read for shiitake or lentinan. The monograph notes that chronic shiitake use may increase eosinophil count, a type of white blood cell. [21] Ask a pharmacist; see how interactions work.
  • Allergy and spores: the monograph lists pneumonia caused by hypersensitivity to spores. [6] See mushroom allergy and food intolerance.
References
  1. Shiitake dermatitis: experience of the Poison Control Centre Network in France from 2014 to 2019. Clinical Toxicology, 2022. Read 2026-10-23.
  2. Shiitake dermatitis: experience of the Poison Control Centre Network in France from 2014 to 2019. Clinical Toxicology, 2022. Read 2026-10-23.
  3. Shiitake dermatitis: experience of the Poison Control Centre Network in France from 2014 to 2019. Clinical Toxicology, 2022. Read 2026-10-23.
  4. Shiitake dermatitis: experience of the Poison Control Centre Network in France from 2014 to 2019. Clinical Toxicology, 2022. Read 2026-10-23.
  5. Memorial Sloan Kettering Cancer Center, Shiitake Mushroom (About Herbs). Read 2026-10-23.
  6. Memorial Sloan Kettering Cancer Center, Shiitake Mushroom (About Herbs). Read 2026-10-23.
  7. Global Biodiversity Information Facility (GBIF), species match for Lentinula edodes, usage key 2537743. GBIF species page. Read 2026-10-23 through the GBIF species-match service.
  8. Lentinan progress in inflammatory diseases and tumor diseases. European Journal of Medical Research, 2024 (review). Read 2026-10-23.
  9. Memorial Sloan Kettering Cancer Center, Shiitake Mushroom (About Herbs). Read 2026-10-23.
  10. Lentinan progress in inflammatory diseases and tumor diseases. European Journal of Medical Research, 2024 (review). Read 2026-10-23.
  11. Individual patient based meta-analysis of lentinan for unresectable/recurrent gastric cancer. Anticancer Research, 2009. Read 2026-10-23.
  12. Randomised phase III study of S-1 alone versus S-1 plus lentinan for unresectable or recurrent gastric cancer (JFMC36-0701). European Journal of Cancer, 2016. Read 2026-10-23.
  13. Randomised phase III study of S-1 alone versus S-1 plus lentinan for unresectable or recurrent gastric cancer (JFMC36-0701). European Journal of Cancer, 2016. Read 2026-10-23.
  14. Systematic review and meta-analysis on the efficacy and safety of injectable lentinan combined with chemotherapy in the treatment of gastric cancer. Phytomedicine, 2024. Read 2026-10-23.
  15. Memorial Sloan Kettering Cancer Center, Shiitake Mushroom (About Herbs). Read 2026-10-23.
  16. Modulation of human intestinal microbiota in a clinical trial by consumption of a beta-D-glucan-enriched extract obtained from Lentinula edodes. European Journal of Nutrition, 2021. Read 2026-10-23.
  17. Modulation of human intestinal microbiota in a clinical trial by consumption of a beta-D-glucan-enriched extract obtained from Lentinula edodes. European Journal of Nutrition, 2021. Read 2026-10-23.
  18. Effects of fungal beta-glucans on health: a systematic review of randomized controlled trials. Food & Function, 2021. Read 2026-10-23.
  19. Effects of fungal beta-glucans on health: a systematic review of randomized controlled trials. Food & Function, 2021. Read 2026-10-23.
  20. Memorial Sloan Kettering Cancer Center, Shiitake Mushroom (About Herbs). Read 2026-10-23.
  21. Memorial Sloan Kettering Cancer Center, Shiitake Mushroom (About Herbs). Read 2026-10-23.
  22. Mushroom polysaccharide lentinan for treating different types of cancers: a review of 12 years clinical studies in China. Progress in Molecular Biology and Translational Science, 2019. Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.