Shiitake, an edible mushroom indigenous to East Asia, is cultivated worldwide for its purported health benefits
ALSO KNOWN AS: Forest mushroom, lentinula, black mushroom, hua gu.
BACKGROUND: Shiitake, an edible mushroom indigenous to East Asia, is cultivated worldwide for its purported health benefits. The fresh and dried forms of the mushroom are commonly used in East Asian cooking. It is also valued as a medicinal mushroom. Shiitake is popular in many countries around the world and is commonly found in supermarkets and Asian grocery stores.
Lentinan ([1,3] beta-D-glucan), a polysaccharide isolated from shiitake, is thought to be responsible for many of the mushroom's beneficial effects. An injectable form of lentinan is used for cancer treatment in some countries, but it has not been evaluated in large studies.
RESEARCH: In vitro studies conducted with lentinan have indicated its anticancer effects in colon cancer cells; these effects may result from its ability to suppress cytochrome P450 1A enzymes that are known to metabolize pro-carcinogens to active forms.
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For additional information, visit the Memorial Sloan-Kettering Cancer Center Integrative Medicine Service website, "About Herbs," at
Lentin, the protein component of shiitake, exerts antifungal properties, inhibits proliferation of leukemic cells, and suppresses the activity of HIV-1 reverse transcriptase.
Studies of shiitake extracts suggest antiproliferative, immunostimulatory, hepatoprotective, antimutagenic, and anticaries effects in vitro and in mice. But a clinical trial failed to show any benefit of an oral shiitake extract in the treatment of prostate cancer.
More recently, however, improvements were reported in quality of life and survival with an oral formulation of superfine dispersed lentinan in patients with hepatocellular carcinoma, gastric cancer, colorectal cancer, and pancreatic cancer. Larger, well-designed studies are needed to determine whether oral lentinan is superior to the injectable form.
ADVERSE REACTIONS: None have been reported at normal doses. However, there have been a handful of case reports documenting adverse effects associated with shiitake in some way. Chronic hypersensitivity pneumonitis was observed in a lung cancer patient following exposure to shiitake spores. Prolonged consumption of shiitake powder has resulted in dermatitis, photosensitivity, eosinophilia, and gastrointestinal upset. Intermittent skin eruptions (dermatitis), over a period of 16 years, were linked to consumption of shiitake mushrooms in a 45-year-old male. Food allergy manifesting as esophageal symptoms was reported in a 37-year-old man following consumption of shiitake mushroom.
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13. Suzuki K, Tanaka H, Sugawara H, et al. Chronic hypersensitivity pneumonitis induced by Shiitake mushroom spores associated with lung cancer. Intern Med. 2001;40:1132-5.
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