Shiitake Mushrooms: Champion of the Immune System

Lentinula Edodes

is a mushroom native to East Asia, which is now cultivated worldwide for culinary and medicinal purposes. This mushroom is usually referred to as Shiitake, which is its Japanese common name, based upon the “Shii” tree that the mushroom grows on.

Shiitake has been cultivated for over 1000 years. During the Ming Dynasty (A.D. 1368-1644) Chinese physician Wu Jue wrote that the mushroom could be used medicinally as a remedy for upper respiratory tract infections, poor circulation, liver pathologies, exhaustion, premature aging, and as a Qi (life force) tonic.

Shiitake has a nutty and earthy taste, making it a common delicacy of the culinary world. Many chefs prefer to use sun-dried Shiitake since the drying process seems to enhance the flavour. Interestingly, the effect of UV light on the mushroom converts ergosterol into vitamin D, making the sun-dried variety a dietary source of this vitamin. Shiitake is often sautéed in Chinese cuisine, used to flavour soup in Japanese cuisine, and steamed, simmered, or fried in Thai cuisine.

From a naturopathic perspective, Shiitake is a fascinating mushroom due to its application in health care, easy incorporation into the diet, and excellent safety profile. Current research is discovering that extracts of this mushroom have immune system regulating properties, along with antibacterial, antiviral, and blood clot inhibiting properties. A study published by the Journal of Microbiology and Biotechnology in 2009 reported that polysaccharide extracts of Shiitake were shown to stimulate the function and activation of macrophages. Macrophages are white blood cells involved in the body’s initial response to infection (destroying pathogens and sending out chemical signals to the immune system to mount an attack on invading organisms).

In 2006, the Biological Pharmacology Bulletin published a study that examined the efficacy of a hot water extract of Shiitake on protecting hepatocytes (liver cells) from the toxic agent D-galactosamine. The result was that 0.5 mg/ml of the Shiitake extract completely suppressed the cytotoxic (liver cell death inducing) effects of D-galactosamine. The study continued to examine the effect of injecting the Shiitake extract into rats treated with D-galactosamine. The result was less leakage of AST and ALT (both chemical blood markers of liver cell injury).

Lentinan, a common extraction of Shiitake used for medicinal purposes, was researched with regard to its immune regulatory applications in individuals living with HIV. In 1998, the Journal of Medicine (AIDS Activities Division, San Francisco General Hospital) conducted a double-blind placebo control trial on 98 patients with HIV. Patients were administered either 2, 5, or 10 mg of Lentinan or placebo via intravenous (I.V.) once a week for eight weeks. Side effects of the I.V. administered Lentinan were generally mild when administered over a 30-minute period. The patients in the study receiving Lentinan demonstrated a trend toward increases in CD4 cells (the white blood cells targeted for destruction by HIV), and in some patients, increased neutrophil  (the primary white blood cell involved in the response to infection) activity.

Like all things we ingest, there is potential for allergic reaction to Shiitake. Be careful and observant when ingesting crude Shiitake or Shiitake extract for the first time. Shiitake is easy and inexpensive to grow at home and makes for a healthy and flavourful addition to one’s culinary palate.

SHIITAKE RECIPE

Shiitake mushrooms can be substituted for white or brown mushrooms. As a snack, try a simple Shiitake sauté with garlic, olive oil, soy sauce, and a bit of butter or olive oil, sea salt, and pepper.

It is easy to make traditional Shiitake dashi (Japanese mushroom soup stalk). Just add 18-20 dried Shiitake mushrooms and a strip of kombu (kelp) to 8 cups of water. Let the mixture sit until the water darkens and the mushrooms become completely soft. Now you can use the rehydrated Shiitake’s for other dishes and the stalk can be used for anything from soup stalk to risotto stalk.

To purchase a Shiitake mushroom log in Toronto, check out www.youngurbanfarmers.com.