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Other common
name(s): Japanese mushroom, Black Forest mushroom, golden
oak mushroom, oakwood mushroom
Scientific/medical
name(s): Lentinus
edodes, Lentinula
edodes
Description
A shiitake mushroom is an edible fungus native to Asia and
grown in forests. Shiitake mushrooms are the second most commonly
cultivated edible mushrooms in the world. Extracts from the mushroom,
and sometimes the whole dried mushroom, are used in herbal remedies.
Overview
Studies in animals have found antitumor, cholesterol-lowering,
and virus-inhibiting effects in compounds in shiitake mushrooms.
However, clinical studies are needed to determine whether these
properties can help people with cancer and other diseases. It is
reasonable to include shiitake mushrooms as part of a balanced diet.
How is it promoted for use?
Shiitake mushrooms are promoted to fight the development and
progression of cancer and AIDS by boosting the body's immune system.
These mushrooms are also said to help prevent heart disease by lowering
cholesterol levels and to help treat infections such as hepatitis by
producing interferon, a group of natural proteins that stops viruses
from multiplying. Promoters claim that eating both the cap and stem of
the mushroom may be helpful, but they do not say how much must be eaten
to have an effect. They say the strength and effects of the mushroom
depend on how it is prepared and consumed.
Promoters claim that shiitake mushrooms contain several
compounds with health benefits. A compound called lentinan is believed
to stop or slow tumor growth. Another component, activated
hexose-containing compound (also known as 1,3-beta glucan), is also
said to reduce tumor activity and lessen the side effects of cancer
treatment. The mushrooms also contain the compound eritadenine, which
is thought to lower cholesterol by blocking the way cholesterol is
absorbed into the bloodstream. These claims are currently being
studied.
What does it involve?
The fresh or dried whole mushroom is widely available in
grocery stores, while extracts of the mushroom are sold in capsule form
in health food stores and on the Internet. Kits for growing shiitake
mushrooms indoors at home are available from some Internet sellers.
For medicinal purposes, the extracts of compounds in shiitake
mushrooms would usually be recommended, rather than the mushroom
itself. For example, some Japanese researchers give lentinan along with
chemotherapy to treat patients with lung, nose, throat, and stomach
cancer. Extracts of the active compounds, such as lentinan and
eritadenine, are mainly sold in Japan. Activated hexose-containing
compound is sold as a nutritional supplement in the United States,
Europe, and Japan.
What is the history behind it?
Medicinal use of shiitake mushrooms dates at least to 100 AD
in China (see Chinese Herbal Medicine). The mushrooms have been widely
consumed as a food for thousands of years in the East and more recently
in the West. Today, shiitake mushrooms are very popular in the United
States as well. Research into the anticancer properties of shiitake
mushrooms has been going on since at least the 1960s.
What is the evidence?
Animal studies have shown some positive results regarding the
antitumor, cholesterol-lowering, and virus-inhibiting effects of
several active compounds in shiitake mushrooms.
There have been some studies in humans. At least one
randomized clinical trial of lentinan has shown it to prolong life of
patients with advanced and recurrent stomach and colorectal cancer who
were also given chemotherapy. Lentinan is a beta glucan (sometimes
called beta glycan) that is found in several mushrooms, yeasts, and
other foods. Beta glucan is a polysaccharide, a large and complex
molecule made up of smaller sugar molecules. The beta glucan
polysaccharide is believed to stimulate the immune system and activate
certain cells and proteins that attack cancer, including macrophages,
T-cells, and natural killer cells. In laboratory studies, beta glucan
appears to slow the growth of cancer in some cell cultures.
Several potential cancer-fighting substances have been found
in shiitake mushrooms, and purified forms of these compounds are being
studied as treatment for stomach and colorectal cancer. It is not known
whether any of these results will apply to the mushrooms bought in
supermarkets or the extracts that are sold as supplements. One
nonrandomized study published in 2002 looked at use of shiitake
mushroom extract by men with prostate cancer but did not find any
positive effect. Sixty-two men took the extract 3 times a day. After 6
months, they did not have any significant decrease in their level of
prostate-specific antigen (PSA), a protein in the body that typically
increases as prostate cancer grows, and nearly a quarter of them had
increases in their PSA level. More human clinical trials are under way
to understand which, if any, compounds in shiitake mushrooms may be
effective for which types of cancers.
To reduce cancer risk, the American Cancer Society's nutrition
guidelines recommend eating a balanced diet that includes five or more
servings a day of vegetables and fruit, choosing whole grains over
processed and refined foods, and limiting red meats and animal fats.
Choosing foods from a variety of fruits, vegetables and other plant
sources such as nuts, seeds, whole grain cereals, and beans is
healthier than consuming large amounts of one particular food. (For
more information, see American Cancer Society
Guidelines on Nutrition and Physical Activity for Cancer Prevention.)
Are there any possible problems or
complications?
This product is sold as a
dietary supplement in the United States. Unlike companies that produce
drugs (which must provide the FDA with results of detailed testing
showing their product is safe and effective before the drug is approved
for sale), the companies that make supplements do not have to show
evidence of safety or health benefits to the FDA before selling their
products. Supplement products without any reliable scientific evidence
of health benefits may still be sold as long as the companies selling
them do not claim the supplements can prevent, treat, or cure any
specific disease. Some such products may not contain the amount of the
herb or substance that is written on the label, and some may include
other substances (contaminants). Though the FDA has written new rules
to improve the quality of manufacturing processes for dietary
supplements and the accurate listing of supplement ingredients, these
rules do not take full effect until 2010. And, the new rules do not
address the safety of supplement ingredients or their effects on health
when proper manufacturing techniques are used.
Most such
supplements have not been tested to find out if they interact with
medicines, foods, or other herbs and supplements. Even though some
reports of interactions and harmful effects may be published, full
studies of interactions and effects are not often available. Because of
these limitations, any information on ill effects and interactions
below should be considered incomplete.
Shiitake mushrooms and their extracts are generally considered
safe, although there are reports of diarrhea or bloating. In some
people, allergic reactions have developed affecting the skin, nose,
throat, or lungs. Relying on this type of treatment alone and avoiding
or delaying conventional medical care for cancer may have serious
health consequences.
Additional Resources
More information from your American Cancer
Society
The following information on complementary and alternative
therapies may also be helpful to you. These materials may be found on
our Web site (www.cancer.org)
or ordered from our toll-free number (1-800-ACS-2345).
References
Borchers AT, Stern JS, Hackman RM, Keen CL, Gershwin ME.
Mushrooms, tumors, and immunity. Proc
Soc Exp Biol Med. 1999;221:281-293.
Chihara G, Hamuro J, Maeda Y, Shiio T, Suga T, Takasuka N,
Sasaki T. Antitumor and metastasis-inhibitory activities of lentinan as
an immunomodulator: an overview. Cancer
Detect Prev Suppl. 1987;1:423-443.
Chung R. Functional properties of edible mushrooms. Nutr Rev.
1996;54:S91-S93.
Cunningham-Rundles S, Lin H, Cassileth B. Are botanical
glucans effective in enhancing tumoricidal cell activity? American
Society for Nutrition. J
Nutr. 2005;135: 2919S.
deVere White RW, Hackman RM, Soares SE, Beckett LA, Sun B.
Effects of a mushroom mycelium extract on the treatment of prostate
cancer. Urology.
2002;60:640-644.
Fang N, Li Q, Yu S, Zhang J, He L, Ronis MJ, Badger TM.
Inhibition of growth and induction of apoptosis in human cancer cell
lines by an ethyl acetate fraction from shiitake mushrooms. J Altern Complement Med.
2006;12:125-132.
Ikekawa T, Uehara N, Maeda Y, Nakanishi M, Fukuoka F.
Antitumor activity of aqueous extracts of edible mushrooms. Cancer Res.
1969;29:734-735.
Kawaoka T, Yoshino S, Kondo H, Yamamoto K, Hazama S, Oka M.
Clinical evaluation of intrapleural or peritoneal repetitive
administration of Lentinan and OK-432 for malignant effusion [in
Japanese]. Gan to
Kagaku Ryoho [Japanese Journal of Cancer &
Chemotherapy]. 2005;32:1565-1567.
Ko YT, Lin YL. 1,3-beta-glucan quantification by a
fluorescence microassay and analysis of its distribution in foods. J Agric Food Chem.
2004;52:3313-3318.
Kodoma N, Komuta K, Nanba H. Can maitake MD-fraction aid
cancer patients? Altern
Med Rev. 2002;7(3):236-239.
Comment in:
Altern Med Rev.
2002;7(6):236-451; author reply 452-454.
Konno S. Potential growth inhibitory effect of maitake
D-fraction on canine cancer cells. Vet
Ther. 2004;5:263-271.
Kushi LH, Byers T, Doyle C, Bandera EV, McCullough M,
McTiernan A, Gansler T, Andrews KS, Thun MJ; American Cancer Society
2006 Nutrition and Physical Activity Guidelines Advisory Committee.
American Cancer Society guidelines on Nutrition and Physical Activity
for cancer prevention: reducing the risk of cancer with healthy food
choices and physical activity. CA
Cancer J Clin. 2006;56:254-281.
Matsushita K, Kuramitsu Y, Ohiro Y, Obara M, Kobayashi M, Li
YQ, Hosokawa M. Combination therapy of active hexose correlated
compound plus UFT significantly reduces the metastasis of rat mammary
adenocarcinoma. Anticancer
Drugs. 1998;9:343-350.
Nagahashi S, Suzuki H, Nishiwaki M, Okuda K, Kurosawa Y,
Terada S, Sugihara T, Andou K, Hibi T. TS-1/CDDP/Lentinan combination
chemotherapy for inoperable advanced gastric cancer [in Japanese]. Gan to Kagaku Ryoho
[Japanese Journal of Cancer & Chemotherapy]. 2004;31:1999-2003.
Shiitake mushroom. Memorial Sloan-Kettering Cancer Center.
Accessed at: http://www.mskcc.org/mskcc/html/69377.cfm on June 10,
2008.
Taguchi T. Clinical efficacy of lentinan on patients with
stomach cancer: end-point results of a four-year follow-up survey. Cancer Detect Prev Suppl.
1987;1:333-349.
Note: This information may not cover
all possible claims, uses, actions, precautions, side effects or
interactions. It is not intended as medical advice, and should not be
relied upon as a substitute for consultation with your doctor, who is
familiar with your medical situation.
Last Medical Review: 11/01/2008
Last Revised: 11/01/2008
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