Photo courtesy
By Pooja Sainarayan
Local Journalism Initiative
Chaga, Inonotus obliquus is a fungus that grows on tree trunks, mainly on yellow and white birch trees found in Quebec as well as other parts of Canada. Chaga flourishes in extreme cold environments making Canadian chaga highly valued. The fungi exists as an encrusted black growth on the trunks called a conk, which absorbs nutrients from the wood. Chaga mushrooms can be found on wounded trees where the conk grows out of the broken branches or trunks. The fungus shields the tree’s wounds and protects it from invasive microbes. Although loggers referred to this fungus as “tree cancer”, it has recently exploded in popularity in the west due to its many natural medicinal properties. The host tree and chaga can co-exist in symbiosis for several years, and the mushroom can be collected up to three times over the course of its lifetime. The chaga actually extends the life of the host tree so that the fungi can survive.
Trees that look similar to birch such as aspen may sometimes be infected with the chaga mushroom, however chaga taken from these species of trees is thought to contain less medicinal properties than the birch chaga does. To harvest the mushroom, it is important to leave enough behind so that the fungus is still touching the exterior of the tree. This ensures that the tree remains protected against any further environmental damage or future infections. Chaga usually grows high up on the tree, so in order to harvest the fungi, one would need to climb the tree. In addition, chaga that is found higher up is speculated to be more potent. Harvesting chaga from fallen or dead trees, or chaga that has fallen to the ground is not advised as it may be contaminated with mycotoxins. This is known as “dead chaga” and is black from the inside and out. Trees containing chaga growing on or close to contaminated lands, mills and industrial areas is also not recommended to harvest. When harvesting the fungi, it should be the size of a large soft ball at minimum and using the proper tools such as an axe, machete, or battery-operated saw is required as it is difficult to separate from the trunk. Proper harvesting and handling methods are key to reaping the most benefits.
Once the chaga has been harvested, it can be processed for consumption. The black outer crust should not be discarded. An air compressor can be used to blast away any dirt and bark. Chaga must be dried immediately following harvest in a well-ventilated area, or kept in a deep freezer if processed at a later time. Placing the chaga to dry quickly in a hot oven is speculated to remove most of its biologically active nutrients, however a commercial food dehydrator can be used. The fresh chaga must be cut into approximately 2-inch pieces to dry until the pieces are stiff and crumbly. The dried chaga can then be storied in an air-tight sealed container for several years.
The history of the chaga mushrooms dates back to centuries, where it was used in ayurvedic and traditional Chinese medicine. Chaga tea has also been used in Russia since the 16th century, as well as in Poland and other Baltic countries. The fungus is believed to have several health benefits such as antioxidant and anti-cancer properties. In addition, it was also used to treat gastric problems, tuberculosis, diabetes, arthritis, and cardiovascular disease. Chaga was also used for centuries by Canadian aboriginal First Nations people. So, let us look at any possible scientific evidence to support the medicinal properties of chaga.
According to a 2021 article published in the Polymers journal, the extract from chaga mushrooms, known as Inonotus obliquus polysaccharide (IOPS), which is a major bioactive component present in the mushrooms, exhibited significant hypoglycemic, hypolipidemic, antioxidant, anti-fatigue properties, as well as cytotoxicity towards several cancer cells such as hepatic carcinoma, lung cancer, ovarian and cervical cancers. In addition, the low toxicity of the chaga mushrooms makes it more attractive for further investigations. However, the polysaccharide composition and content variations between the natural habitat environment and extraction methods are not the same. Therefore, the standardization of planting and extraction is of high importance. Other studies have shown that the various bioactive compounds, including polysaccharides, triterpenoids, polyphenols, and lignin metabolites are responsible for the many health-benefiting properties of the fungus. Further investigations in the precise mechanisms of the compounds found in chaga and its interactions with enzymes or proteins of the relevant pathways are required to establish more concrete scientific evidence in its health benefits.