Health Benefits Of Shiitake Mushrooms

Health Benefits Of Shiitake Mushrooms
Other Common Names:: Hua gu, Lentinan edodes

The cultivation of L. edodes (shiitake) first began in China about
AD 1100. It is believed that shiitake cultivation techniques developed
in China were introduced to the Japanese by Chinese growers.

Various species of trees have been used for the cultivation of
shiitake. One of the primary species used in one area of Japan in past
years was the shii tree--thus the derivation of the name shii-take.
Most production today, however, is on various species of oak.

Medicinal properties have been attributed to mushrooms for thousands
of years. Mushroom extracts are widely sold as nutritional supplements
and touted as beneficial for health.

Shiitake is one of the best known and best characterized mushrooms
used for medicinal purposes. Several medicinal properties have been
attributed to shiitake in recent years. These properties include
antitumor polysaccharides activity and glycoproteins, antiviral nucleic
acids, platelet agglutination inhibitive substances, and
anti-cholesterol active substances.

Lentinan, which is the name given a highly purified polysaccharide
fraction extracted from Shiitake mushrooms, is an approved drug in
Japan. It is generally administered by injection and has been used as
an agent to prolong survival of patients in conventional cancer therapy
as well as in AIDS research. Lentinan is commercially available for
clinical use. Lentinan is not only useful for cancer treatment, but may
also prevent the increase of chromasomal damage induced by anti-cancer
drugs. Additionally, Shiitake contains all eight essential amino acids
in better proportions than soy beans, meat, milk, or eggs as well as a
good blend of vitamins and minerals including vitamins A, B, B12, C, D
and Niacin.

In the last three decades, numerous polysaccharides and
polysaccharide-protein complexes have been isolated from mushrooms and
used as a source of therapeutic agents. The most promising
biopharmacological activities of these biopolymers are their
immunomodulation and anti-cancer effects. Three antitumor mushroom
polysaccharides, have become large market items in Japan.

Although the mechansim of their antitumor action is still not
completely clear, these polysaccharides and polysaccharide-protein
complexes are suggested to enhance cell-mediated immune responses in
vivo and in vitro and act as biological response modifiers.
Potentiation of the host defense system may result in the activation of
many kinds of immune cells that are vitally important for the
maintenance of homeostasis. Polysaccharides or polysaccharide-protein
complexes are considered as multi-cytokine inducers that are able to
induce gene expression of vaious immunomodulatory cytokines and
cytokine receptors. Some interesting studies focus on investigation of
the relationship between their structure and antitumor activity,
elucidation of their antitumor mechanism at the molecular level, and
improvement of their various biological activities by chemical
modifications.

• Nakamura, N. 1983. An historical study in shiitake (mushroom) culture. Tosen Shuppon, Tokyo.
  
• Mizuno, T. 1995a. Shiitake, Lentinus edodes: functional properties
  for medicinal and food purposes. Food Rev. Int. 11(1):111-128.
  
• Ooi, VE. Liu, F. Immunomodulation and Anti-Cancer Activity of Polysaccharide-Protein Complexes.