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.
Usually, Chaga is prepared as a tincture or brewed to make a tea. To make a tea, use 10 grams of powder to 1 liter of water and brew this for 2 to 4 hours. Do not bring the water to a full boil, as this will destroy important chemicals. The problem with boiling is that medicinal components of Chaga include not only polysaccharides but proteins, sterols, enzymes including catalase, peroxidase, all of which are damaged or destroyed by temperatures above 180ºF. Instead, use ground Chaga and either steep or simmer it in a crock pot using low to medium heat. The tea is complete whenever the liquid becomes as dark as coffee. Unused tea can be stored frozen in ice cube trays and then added to other beverages. Brew the tea longer for a more concentrated product. For convenience, Chaga powder may also be added to smoothies.
Chaga is recognized as a safe natural mushroom used for centuries with no known complications. The World Health Organization has accorded it G.R.A.S. (Generally Recognized as Safe) status.
Rzymowska J (1998) The effect of aqueous extracts from Inonotus obliquus on the mitotic index and enzyme activities. Boll Chim Farm 137:l3–15.
Kukulyanskaya TA, Kurchenko NV, Kurchenko VP, Babitskaya VG. Physicochemical properties, of melanins produced by the sterile form of Inonotus obliquus (“Chagi”) in natural and cultivated fungus. Appl Biochem Microbiol. 2002;38:58–61.
He J, Feng XZ, Lu Y, Zhao B. Three new triterpenoids from Fuscoporia obliqua. J Asian Nat Prod Res. 2001;3(1):55–61.
Mizuno, Takashi, Cun Zhuang, Kuniaki Abe, Hidehumi Okamoto, Tadashi Kiho, Shigeo Ukai, Sophie Leclerc, and Laurent Meijer. Antitumor and hypoglycemic activities of polysaccharides from the sclerotia and mycelia of Inonotus obliquus (Pers.: Fr.) Pil.(Aphyllophoromycetideae). International Journal of Medicinal Mushrooms 1, no. 4 (1999).
Kim, Yong Ook, Hae Woong Park, Jong Hoon Kim, Jae Young Lee, Seong Hoon Moon, and Chul Soo Shin. Anti-cancer effect and structural characterization of endo-polysaccharide from cultivated mycelia of Inonotus obliquus. Life Sciences 79, no. 1 (2006): 72-80.
Kim, Yong Ook, Sang Bae Han, Hong Woen Lee, Hyo Jung Ahn, Yeo Dae Yoon, Joon Ki Jung, Hwan Mook Kim, and Chul Soo Shin. Immuno-stimulating effect of the endo-polysaccharide produced by submerged culture of Inonotus obliquus. Life Sciences 77, no. 19 (2005): 2438-2456.
Song, Yana, Jing Hui, Wei Kou, Ru Xin, Fei Jia, Ning Wang, Fengqing Hu, Huili Zhang, and Hongsheng Liu. Identification of Inonotus obliquus and analysis of antioxidation and antitumor activities of polysaccharides. Current microbiology57, no. 5 (2008): 454.
Mizuno T, Zhuang C, Abe K, Okamoto H, Kiho T, Ukai S, Leclerc S, Meijer L. Antitumor and hypoglycemic activities of polysaccharides from the Sclerotia and Mycelia of Inonotus obliquus (Pers:Fe.) Pll. (Aphyllophoromycetideae). International Journal of Medicinal Mushrooms 1999;1:301–316.
Kim YO, Park HW, Kim JH, Lee JY, Moon SH, Shin CS: Anticancer effect and structural characterization of endo-polysaccharide from cultivated mycelia of Inonotus obliquus. Life Sci 79 : 72-80, 2006.
Ham SS, Kim SH, Moon SY, Chung MJ, Cui CB, Han EK, Chung CK, Choe M. Antimutagenic effects of subfractions of Chaga mushroom (Inonotus obliquus) extract. Mutat Res 2009;672:55–59.
Ham SS, Oh SW, Kim YK, Shin KS, Chang HY, Chung GH. Antimutagenic and cytotoxic effects of ethanol extract from the Inonotus obliquus. J Korean Soc Food Sci Nutr 2003;32:1088–1094.
Fan, Liuping, Shaodong Ding, Lianzhong Ai, and Kequan Deng. Antitumor and immunomodulatory activity of water-soluble polysaccharide from Inonotus obliquus. Carbohydrate polymers 90, no. 2 (2012): 870-874.
Nomura M, Takahashi T, Uesugi A, Tanaka R, Kobayashi S. Inotodiol, a lanostane triterpenoid, from Inonotus obliquus inhibits cell proliferation through caspase-3-dependent apoptosis. Anticancer Res 2008;28:2691–2696.
Kim YO, Han SB, Lee HW, Ahn HJ, Yoon YD, Jung JK, Kim HM, Shin CS: Immuno-stimulating effect of the endo-polysaccharide produced by submerged culture of Inonotus obliquus. Life Sci 77 : 2438-2456, 2005.
Youn MJ, Kim JK, Park SY, Kim Y, Park C, Kim ES, Park Kl, So HS, Park R. Potential anticancer properties of the water extract of lnonotus obliquus by induction of apoptosis in melanoma B16-F10 cells. J Ethnopharmacol 2009;121:221–228.
Lee SH, Hwang HS, Yun JW. Antitumor activity of water extract of a mushroom, Inonotus obliquus, against HT-29 human colon cancer cells. Phytother Res. Apr 15 2009.
Park YM, Won JH, Kim YH, Choi JW, Park HJ, Lee KT: In vivo and in vitro anti-inflammatory and anti-nociceptive effects of the methanol extract of Inonotus obliquus. J Ethnopharmacol 101(1-3) : 120-128, 2005.
Won, Dong Pil, Jong Seok Lee, Duck Soo Kwon, Keun Eok Lee, Won Cheol Shin, and Eock Kee Hong. Immunostimulating activity by polysaccharides isolated from fruiting body of Inonotus obliquus. Molecules and cells 31, no. 2 (2011): 165-173.
Youn MJ, Kim JK, Park SY, et al. Chaga mushroom (Inonotus obliquus) induces G0/G1 arrest and apoptosis in human hepatoma HepG2 cells. World J Gastroenterol. Jan 28 2008;14(4):511-517.
Cui, Yong, Dong-Seok Kim, and Kyoung-Chan Park. Antioxidant effect of Inonotus obliquus. Journal of Ethnopharmacology 96, no. 1-2 (2005): 79-85.
Lee, In-Kyoung, Young-Sook Kim, Yoon-Woo Jang, Jin-Young Jung, and Bong-Sik Yun. New antioxidant polyphenols from the medicinal mushroom Inonotus obliquus. Bioorganic & Medicinal Chemistry Letters 17, no. 24 (2007): 6678-6681.
Nakajima, Yuki, Yuzo Sato, and Tetsuya Konishi. Antioxidant small phenolic ingredients in Inonotus obliquus (persoon) Pilat (Chaga). Chemical and Pharmaceutical Bulletin 55, no. 8 (2007): 1222-1226.
Zhao, L. W., X. H. Zhong, Y. M. Sun, S. Y. Yang, Nan Shen, Y. Z. Zhang, N. J. Yang, Kuang Ren, and S. J. Lu. Prevention of Inonotus obliquus polysaccharides for high power microwave radiation induced testicular injury in rats: an experimental research. Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi (Chinese journal of integrated traditional and Western medicine) 34, no. 7 (2014): 864-868.
Zheng, Weifa, Yanxia Zhao, Meimei Zhang, Zhiwen Wei, Kangjie Miao, and Weiguo Sun. Oxidative stress response of Inonotus obliquus induced by hydrogen peroxide. Medical mycology 47, no. 8 (2009): 814-823.
Ng, Tzi Bun, and Charlene Cheuk Wing Ng. Protective Effects of Mushrooms against Tissue Damage with Emphasis on Neuroprotective, Hepatoprotective and Radioprotective Activities. Cultivation, Antioxidant Properties and Health Benefits: 157.
SHIN, Yusoo, Yutaka TAMAI, and Minoru TERAZAWA. Chemical Constituents of Inonotus obliquus Ⅳ.: Triterpene and Steroids from Cultured Mycelia. Eurasian Journal of Forest Research 2 (2001): 27-30.
Nakata, Tomoko, Takeshi Yamada, Sayaka Taji, Hirofumi Ohishi, Shun-ichi Wada, Harukuni Tokuda, Kazuo Sakuma, and Reiko Tanaka. Structure determination of inonotsuoxides A and B and in vivo anti-tumor promoting activity of inotodiol from the sclerotia of Inonotus obliquus. Bioorganic & medicinal chemistry 15, no. 1 (2007): 257-264.
Nomura, Masaaki, Tatsuo Takahashi, Aimi Uesugi, Reiko Tanaka, and Shinjiro Kobayashi. Inotodiol, a lanostane triterpenoid, from Inonotus obliquus inhibits cell proliferation through caspase-3-dependent apoptosis. Anticancer research 28, no. 5A (2008): 2691-2696.
Zheng W, Miao K, Liu Y, Zhao Y, Zhang M, Pan S, et al. (2010). Chemical diversity of biologically active metabolites in the sclerotia of Inonotus obliquus and submerged culture strategies for up-regulating their production. Appl Microbiol Biotechnol. 87 (4): 1237–54. doi:10.1007/s00253-010-2682-4. PMID 20532760.