Shiitake mushroom (Lentinus edodes ) is a fungus native to Japan, China, and Korea. Although these mushrooms are cultivated worldwide as of 2004, Japan is still the largest producer of shiitake mushrooms, producing 80% of the total supply. Used in Asian cuisine for over 2,000 years, cultivation of shiitake began almost 700 years ago in Japan. The Japanese consider the shiitake not only a flavorful food but also "the elixir of life." During the Ming Dynasty (1368–1644), the shiitake was reserved only for the emperor and his family and it became known as the emperor's food. The word shiitake comes from shii (a type of chestnut tree) and take (mushroom). Shiitake is an excellent source for amino acids ; vegetable proteins; iron ; thiamine (vitamin B1); riboflavin (vitamin B2); niacin ; and vitamins B6, B12, and D2. Shiitake is known as hsaing ku (fragrant mushroom) in China.
Traditionally, shiitake was used medicinally for a number of conditions.
- colds and influenza
- sexual dysfunction
Presently, shiitake has been shown to boost the immune system, act as an antiviral and antibacterial agent, and possibly shrink tumors. Since shiitake has been part of the Asian diet, particularly in Japanese cuisine, for hundreds of years, its health benefits have been documented. Most of the formal studies conducted have been in Japan; however Western interest in the mushroom as a possible treatment for cancer and HIV infection has encouraged researchers in the United States and elsewhere to begin formalized studies of its medicinal properties. A 1998 study done in San Francisco of lentinan, a glucan (complex sugar) found in shiitake, found that patients with HIV infection who were given lentinan together with a standard drug for AIDS maintained higher CD4 cell counts for longer periods of time than those who were given the standard drug alone.
The possible health benefits of lentinan have also led to agricultural experiments intended to raise the level of the compound in commercially grown shiitake. Researchers found that mushrooms grown on logs had higher levels of lentinan than mushrooms grown on other types of organic material.
Shiitake contains over 50 different enzymes, including pepsin and trypsin that help digestion, and asparaginase,
which that has been used to treat childhood leukemia . The mushroom also contains chitin, eritadenine, and lentinacin, all of which have been shown to lower serum cholesterol . Further studies completed in 2002 have confirmed the beneficial effects of shiitake in lowering serum cholesterol levels.
Perhaps shiitake's most beneficial ingredient is an activated hexose-containing compound (also known as 1,3-beta glucan). Japanese studies of this compound have supported evidence that it has anticancer properties in humans as well as in animals. The compound is already produced by a private company as a nutritional supplement and is available in Europe, Japan, and the United States. It is also regularly used in hospitals in Asia and Japan in conjunction with allopathic treatments of several kinds of cancer. According to a Hokkaido University School of Medicine study of cancer patients taking the supplement on a daily basis, the compound may slow tumor growth and decrease the side effects caused by allopathic cancer treatments. The University of California Davis School of Medicine is conducting the first human trial outside of Japan to determine the antitumor effects that the activated hexose-containing compound may have on cancer patients. The focus of the study will be on patients with prostrate cancer because the characteristic symptom of the cancer—elevated PSA levels in the blood—are easily detected and monitored for change.
Activated hexose-containing compound is isolated from partially grown mushroom spores that have undergone a treatment that releases the compound. It is not abundant in the mushrooms that are readily available in grocery stores, but the overall health benefits from shiitake mushrooms have been corroborated by research.
Shiitake production in the United States has risen markedly since 1980. Since shiitake is now being marketed as a nutraceutical, or food that is thought to provide health benefits above and beyond its nutritional value, its production is expected to rise even further.
Shiitake mushrooms can be prepared and eaten in the same way the more common white mushrooms are, by grilling, sautéing, and stir-frying. Dried shiitake mushrooms are used in soups, stews, and sauces. Eat one to two fresh mushrooms or 1–2 tsp of dried shiitake daily.
Shiitake supplements are also available in gel-cap form, as well as powders, extracts, and tea at health food stores. Shiitake is also an ingredient in compound formulas to boost the immune system. The newest product of this type is a mixture of dried shiitake, reishi, and maitake mushrooms that have been grown on a base of therapeutic herbs. Consumers who use these products should follow the recommended daily dosage on the label.
Injections of shiitake should be prescribed and monitored by a healthcare provider.
Shiitake is nontoxic and safe to ingest.
Large daily doses over a prolonged period of time can cause diarrhea in some users.
Shiitake has been reported to interact supportively with didanosine (Videx), a drug given to treat HIV infection. Because shiitake can lower blood pressure, it should not be taken together with drugs given to control blood pressure (antihypertensives). For the same reason, it should be discontinued before any operation requiring general anesthesia.
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American Association of Oriental Medicine. 909 22nd Street, Sacramento, CA 95816, (916) 451-6950 <http://www.aaom.org>.
Jacqueline L. Longe
Rebecca J. Frey, PhD