The number of mushroom species on Earth is estimated at 140,000, but perhaps only 10% (approximately 14,000 named species) are known. Mushrooms comprise a vast and yet largely untapped source of powerful new pharmaceutical products. In particular, and most importantly for modern medicine, they represent an unlimited source of chemicals with antitumor and immune stimulating properties. The fungal mycelium Inonotus obliquus, also named Fuscoporia obliqua, has been widely used for more than five centuries in Russia and Eastern European countries to treat gastrointestinal, cardiovascular and liver diseases, as well as different types of cancer. It is commonly known as “Chaga” or “Pakuri,” and is a polypore mycelium in the Hymenochaetaceae family.
Chaga has the appearance of burnt charcoal, mostly black due to the presence of massive amounts of melanin. Once fully grown, Chaga can reach up to 50 cm (20”) in width and height and can have an overhang of about 30 cm. (12”) Chaga grows in colder climates in Russia, China, Canada, Northern Europe, and the Northern U.S. It is primarily found on living birch trees in the more northern parts of Europe, Asia, Canada and in the more northeastern areas of the United States. It is most commonly found on paper (Betula papyrifera) and yellow (Betula alleghaniensis) birch trees. In more northern higher elevation areas, Chaga is found on heart-leaved paper birch (Betula cordifolia) trees. It is also found on cherry birch (Betula lenta) trees in the more southern areas of the U.S. Less frequent host trees include maples, ash and oaks. Because it primarily grows on birch trees, those with allergies to Birch should not consume Chaga in any form. For these allergenic individuals, there are numerous other medicinal mushrooms that can be substituted for Chaga.
In recent years, more than 20 different kinds of bioactive components have been found in Chaga, some quite unique such as beta glucans, phytosterols, triterpenoids - lanostane-type triterpenoids, betulinic acids, polysaccharides, hispidin, inotodiol, trametenolic acid, and lanosterol.1, 2, 3 Generally, the immunological chemicals contained in Chaga do not attack cancer cells directly, but produce their antitumor effects by activating different immune responses in the host.4, 5, 6 Some of their activity is mediated through thymus-dependent immune mechanisms, whereas others are known to stimulate natural killer cells, and macrophage dependent immune system responses. This immunomodulating action is especially valuable as a means of prophylaxis, a mild and non-invasive form of treatment, prevention of metastatic tumors.7
Most research on the pharmacological activity of the fruiting bodies of this fungus has been carried out in research centers in Germany, Japan, Korea and the Republic of China. Chaga has been shown in vitro and in animal models to be both anti-tumorous and anti-carcinogenic.8, 9, 10, 11, 12, 13, 14, It demonstrates selective apoptosis in tumor cells with no harmful effects on healthy cells.15 In one study, Chaga extract was shown to have an inhibitory and proapoptotic effects against colon cancer.16 Chaga has also been shown to be anti-inflammatory, anti-nociceptive17, immunostimulating18, hepatoprotective (liver protective)19, and to possess potent antioxidant properties.20, 21, 22 Like Ganoderma lucidum and Cordyceps Sinensis, Chaga has been shown to reduce toxicity associated with radiation exposure.23, 24, 25 Antitumor experiments with n-hexane extracts of Chaga found that triterpenoids, especially inotodiol, have a significant repressive effect against both Walker 256 carcinosarcoma26, and MCF-7 human mammary adenocarcinoma in vitro27, and against leukemia P388 in vivo.28
Inonotus obliquus Dosage and Availability
A critical problem with Chaga today is that natural reserves of this unique fungus have nearly been exhausted. Widespread harvestings have threatened the delicate ecological balance. Commercial foragers are quickly exhausting the supply of wild Chaga found near roads and hiking trails, making this wild mushroom increasingly hard to find. At least one mushroom company has found a method to cultivate Chaga indoors via sterile tissue culture on a substrate of white sorghum.29
The optimum time for peak nutrients is in autumn after twenty straight nights of temperatures 5 C (41F) or below. This is when the birch trees are in dormancy. Some harvesters believe the optimum time is when the temperatures hit -20 C (-4F). Harvest through the fall and winter as long as possible until the sap starts running. Never remove all the Chaga - the Chaga will not be able to regrow and the tree may be harmed. Harvest only very large conks and leave at least 25% of it on the tree.
Although Chaga is an edible fungus, it is not commonly ingested due to its bitter nature. Chaga must be broken down into a powder form to be added into food, used as a tea, liquid extract or placed into capsules. Chaga is traditionally grated into a fine powder and used to brew a beverage resembling coffee. Currently, three extraction processes are used, each with a different outcome.
Hot water extraction is the most common and the cheapest method. The ß-D-glucans may have a content of ±35% in a pure extract.30
Ethanol extraction isolates the water-insoluble components, betulinic acid, betulin and the phytosterols. This extraction process is generally used as a second step after hot-water extraction, since ethanol alone will not break down chitin effectively - heat is essential.
Fermentation is the most time-consuming, so is the most expensive; this method is not used very often. Fermented Chaga is used in some skin care products to reduce irritation and redness.