Nutritional Supplement


Parts Used & Where Grown

Wild shiitake mushrooms are native to Japan, China, and other Asian countries and typically grow on fallen broadleaf trees. Shiitake is now widely cultivated throughout the world, including the United States. The fruiting body is used medicinally.

How It Works

Shiitake contains proteins, fats, carbohydrates, soluble fiber, vitamins, and minerals. In addition, shiitake’s key ingredient—found in the fruiting body—is a polysaccharide called lentinan. Commercial preparations employ the powdered mycelium of the mushroom before the cap and stem grow. This preparation is called lentinus edodes mycelium extract (LEM). LEM is rich in polysaccharides and lignans.

One preliminary trial suggested that oral shiitake may be useful for people with hepatitis B.1 A highly purified, intravenous form of lentinan is used in Japan and has been reported to increase survival in people with recurrent stomach cancer, particularly when used in combination with chemotherapy.2 Similar findings have been found in one small clinical trial with people suffering from pancreatic cancer.3 Case reports from Japan suggest that intravenous lentinan may be helpful in treating people with HIV infection.4 However, large-scale clinical trials to confirm this action have not yet been performed.

Oral supplementation of lentinan from shiitake has been shown to significantly reduce the recurrence rate of genital warts (condyloma acuminata). A preliminary trial involving a group of men and women with genital warts found that those who took 12.5 mg of lentinan twice a day for two months after laser surgery had significantly fewer recurrences (10.53% recurrence rate) compared to those who only had the laser surgery (47.06% recurrence rate).5


1. Jones K. Shiitake: A major medicinal mushroom. Alt Compl Ther 1998;4:53-9 [review].

2. Taguchi I. Clinical efficacy of lentinan on patients with stomach cancer: End point results of a four-year follow-up survey. Cancer Detect Prevent Suppl 1987;1:333-49.

3. Matsuoka H, Seo Y, Wakasugi H, et al. Lentinan potentiates immunity and prolongs the survival time of some patients. Anticancer Res 1997;17:2751-6.

4. Hobbs C. Medicinal Mushrooms. Santa Cruz, CA: Botanica Press, 1995, 125-8.

5. Guangwen Y, Jianbin Y, Dongqin L, et al. Immunomodulatory and therapeutic effects of lentinan in treating condyloma acuminata. CJIM 1999;5:190-2.

6. Cho YK, Kim Y, Choi M, et al. The effect of red ginseng and zidovudine on HIV patients. Int Conf AIDS 1994;10:215 [abstract no. PB0289].

7. Jones K. Shiitake: The Healing Mushroom. Rochester, VT: Healing Arts Press, 1995.

8. Hobbs C. Medicinal Mushrooms. Santa Cruz, CA: Botanica Press, 1995, 125-8.

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The information presented by Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2020.