Maitake-The Facts And The Controversy

During the 1990s Maitake was the first medicinal mushroom that became really popular in the West. It is one of the most promising medicinal mushrooms in terms of therapeutic potential.

Biology of Maitake

Maitake is the more common -Japanese- name for Grifola frondosa, a wood-degrading mushroom that grows on dead or dying trees in the temperate regions of many countries. In Anglo-Saxon countries it is also known as ‘Hen of the Woods’ (because it looks like a hen sitting on her nest – at least if you have a vivid imagination). In Japanese, ‘Mai’ means dance and ‘Take’ means mushroom, thus ‘Dancing Mushroom’.

It produces large fruiting bodies (usually ± 10 kgs, but in Japan specimens weighing up to 45 kgs (!) have been reported – hence its name ‘King of Mushrooms’) and is one of the most popular edible mushrooms collected in the fall in United States, with a taste that is similar to eggplant in flavor.

In feudal times in Japan the local lords offered Maitake mushrooms to the Shogun, and locals were paid the mushrooms weight in silver. Not bad if you found a 40 kgs specimen (a very rare find, though…)! Even in recent times Maitake hunters have been known to guard the location of their Maitake grounds carefully, sometimes revealing secret spots (where it may fruit for many years in a row) only in a will.

The basic nutritional composition of Maitake. On the right the properties of a 10:1 ‘extract’ (only water has been extracted – not an actual extract)

Like many mushrooms, Maitake’s optimal growing conditions exist within a small bandwidth when it comes to temperature, moisture, humidity, and other environmental factors. It was first discovered and reported from Europe (England, Norway, Denmark and Finland) but is also commonly found in Eastern Canada and the Eastern, Midwestern, and South-Eastern United States, but rarely in the Pacific Northwest. Some parts of Northeastern Japan and the temperate hardwood regions of China have optimal conditions, but the combination of extensive foraging and development have limited its availability in the wild. 

Cultivation

Until about 1980 Maitake was only available from the wild. The first cultivation techniques for Maitake were developed in 1979-1981, so it can be considered a relatively new cultivated mushroom when compared with the 1400-year cultivation history for Auricularia auricula (Jew’s Ear), the 1000-year history for Lentinula edodes (Shiitake) and the 400-year history for Agaricus bisporus (the common white button mushroom).

Typically its mycelium (the ‘roots’ of the mushroom) is inoculated into plastic bags filled with supplemented sterilized sawdust or other wood-containing wastes. The mycelium is allowed to grow through the bag, a process that can take up to a couple of months or more. At that time the sawdust has become annealed together to produce an artificial log.

Cultivating Maitake on wood-containing substrate is important – grains and rice (very cheap, and common in the US, usually) will not produce a high quality product.

When the mycelium begins to run out of food, an opening is made in the bag (in this case the top), and fresh air is allowed to enter. This fresh air, with its increased concentration of oxygen and decreased concentration of carbon dioxide, is a signal to the mycelium that it should form its fruiting body. It is a pretty efficient process, once the grower learns the right conditions for growth and fruiting.

Commercial production of Maitake began in 1981 in Japan. Until the late 90s, Japan was the major producer of Maitake accounting for 98% of worldwide production. Only 325 tons were produced in 1981. By 1997, world production of Maitake reached 331,000 tons. Currently China is the worlds biggest producer of cultivated Maitake.

Professor Hiroaki Nanba, Ph.D.

This article would not be complete without mentioning the Japanese professor Hiroaki Nanba. He is a professor in the Department of Microbial Chemistry at Kobe Pharmaceutical University in Kobe, Japan. He has a Ph.D. in Biochemistry and Immunology from Kyoto University, and is an award-winning researcher on the benefits and activities of medicinal mushrooms, his main focus during the last 3 decades being the study of Maitake constituents and their therapeutic effects.

In the early 1980s he was studying various medicinal mushrooms, especially Shiitake. During these years of research he found that some of the beta-glucans in Maitake have a unique structure (not only the common (1>3)(1>6) beta-glucans but also (1>6)(1>3) beta-glucans are found in Maitake) and he came to the conclusion that these were most likely the most powerful to have been studied to date, much more promising than Lentinan, a beta-glucan complex isolated from Shiitake.

The isolated Maitake beta-glucan fractions demonstrated more pronounced anti-tumor activity in lab and animal tests than other mushroom extracts that had been studied to date (being the early 80s that meant PSK, Lentinan and Schizophyllan). Maitake also demonstrated the most promise as an orally effective immuno-modulator. This made it potentially much easier to use compared to, for example, the well-known Lentinan which only showed good results when injected.

The core of most of his research was isolating/purifying the bioactive beta-glucans by optimizing the existing extraction processes and then testing the resulting extracts in both test tubes and animal models.

It was already known that the beta-glucans found in medicinal mushrooms were most likely responsible for the majority of their therapeutic effects. The problem was always how to efficiently isolate as pure as possible beta-glucan fractions in order to study them. Crude hot water extracts and non-extracted mushroom powders are until today still dominating the market of mushroom-based supplements. Without exception these products have limited to zero therapeutic potential.

In 1984 Nanba purified 6 beta-glucan fractions (A – F) from the fruiting body of Maitake, each one more pure than the previous one. One of these fractions clearly stood out, therapeutically speaking; being the fourth stage it was labeled ‘D-fraction’. The E-fraction (a further purified version of the D-fraction) also showed very strong anti-tumor activity, but only when injected. The D-fraction extraction / purification protocol was patented in Japan (1984 – JP5921-000901). The D-fraction is a proteoglycan complex (beta-glucans bonded with proteins) with a high molecular weight (± 1000 kD) and a glucan / protein ratio of ± 7 : 3. (2.33).

In 1997 Nanba found a way to optimize the D-fraction extraction protocol even more without losing the important oral administration factor (which was a problem with his E- and F-fraction) and his funding party (Yukiguni, Japan) patented the new procedure; this more pure variation of the D-fraction is known as the MD-fraction.

The MD-fraction is a major improvement over