Maitake Extracts and Their Therapeutic Potential — A Review

Alternative Medicine Review, Feb, 2001 by Mark Mayell

Abstract

Maitake (Grifola frondosa) is the Japanese name for an edible fungus with a large fruiting body characterized by overlapping caps. It is a premier culinary as well as medicinal mushroom. Maitake is increasingly being recognized as a potent source of polysaccharide compounds with dramatic health-promoting potential. The most recent development is the MD-fraction, a proprietary maitake extract its Japanese inventors consider to be a notable advance upon the preceding D-fraction. The D-fraction, the MD-fraction, and other extracts, often in combination with whole maitake powder, have shown particular promise as immunomodulating agents, and as an adjunct to cancer and HIV therapy. They may also provide some benefit in the treatment of hyperlipidemia, hypertension, and hepatitis.

(Altern Med Rev 2001;6(1):48-60)

Maitake: A Premier Mushroom

The scientific name Grifola frondosa is derived from the griffin, the beast from Greek mythology with the head and wings of an eagle and the body of a lion, and frondosa, meaning leaflike. In Japanese, mai means dance and take means mushroom, thus "dancing mushroom." It is not known whether the name came about because the fruiting bodies of adjacent fungi overlap each other, looking like nymphs or butterflies in a wild dance, or because mushroom seekers who were lucky enough to come upon maitake in the wild would dance for joy. In feudal times maitake apparently was so valued it was worth its weight in silver. Even in recent times maitake hunters have been known to jealously guard the location of their maitake grounds, sometimes revealing secret spots (where it may fruit for many years) only in a will. Maitake remains highly sought after by chefs and gourmands for its excellent taste and texture (somewhat like chicken or game hen)[1] and for non-culinary reasons by others for its beneficial health effects.

Maitake often occurs as a heavy mass (clumps may weigh many pounds) at the base of stumps and on the roots of oaks, elms, persimmons, and other trees. Like many other fungi, maitake's optimal growing conditions exist within a limited range for temperature, moisture, humidity, and other environmental factors. Parts of northeastern Japan are especially hospitable for maitake, although foraging and development have combined to limit its availability in the wild. Maitake can also be found in the northern temperate forests of Asia, Europe, and eastern North America. While relatively rare in the wild in Japan, maitake is not an uncommon forest mushroom in the United States and Canada, where it is known as hen of the woods (because the shape and color of its clusters bear a likeness to the tail feathers of a hen) and sheep's head. Only rarely is it found in the western United States.

Closely related species include Grifola umbellata, which the Chinese call zhu ling or chuling, G. albicans, and G. gigantea. The Chinese sometimes include zhu ling (they use the sclerotium rather than the fruiting body) as an ingredient in herbal tonic formulas. Although zhu ling and the other Grifolas are not as thoroughly studied as maitake, they are thought to have similar compounds and health effects.

Maitake cultivation is a recent development. Only within the past two decades have producers been able to switch from a reliance on foraged maitake to offering cultivated maitake. Current bottle- or bag-culture often makes use of a bed of sawdust/bran/soybean cake (in an 80:10:10 ratio) as the base.[2] Japanese commercial cultivation, mainly for food, started in 1981 with 325 tons.[3] It grew to 1,500 tons in 1985, 8,000 tons in 1991, and almost 10,000 tons in 1993. Commercial maitake production worldwide may now be in excess of 40,000 tons.

Within the past two decades maitake has also begun to be cultivated for use as a dietary supplement. It may be the most versatile and promising medicinal mushroom supplement, though currently less well-known than shiitake (Lentinus edodes) and reishi (Ganoderma lucidum).

Mushrooms' Unique and Active Compounds

Some 50 of the 38,000 species of mushrooms have been found to have medicinal properties, according to mushroom researcher Cun Zhuang, PhD. Three have been used as the source for extracts now employed clinically as anticancer drugs in Japan:

* Kawaratake (Coriolus versicolor) is the source for PSK (Krestin). Developed in the late 1970s, PSK was the first mushroom-based anticancer drug and is now one of the most popular anticancer drugs in Japan. It is taken orally for gastric and other cancers.

* Shiitake is the source for Lentinan, which has been approved since the mid-1980s to treat gastric cancer. Because of poor absorption when taken orally, this compound is best administered by injection.

* Suehirotake (Schizophyllum commune) is used to derive Shizophyllan, which is used to treat cervical cancer (it also is injected).

These anticancer medications, as well as many additional medicinal mushrooms such as reishi, hiratake or oyster (Pleurotus ostreatus), and enokitake (Flammulina velutipes), contain various compounds with diverse biological and therapeutic effects. The content and bioactivity of these compounds depend on how the mushroom is prepared and consumed.[4] Among the most important constituents are certain polysaccharides, known as beta-glucans, which are bound to proteins. PSK, Lentinan, and Shizophyllan are all forms of beta-glucan. Maitake's prominent immuneboosting effects are thought to be due predominantly to these polysaccharides.