Chaga is the common name applied to the medicinal fungus Inonotus obliquus. This species is saprotrophic, meaning it feeds on tree wood, having various possible hosts but tending to preference birch trees. Notably, Chaga is not a mushroom and looks vastly different to fun
gal fruiting bodies. It has the appearance of burnt charcoal protruding from the trunk of its host. This represents one of the rare cases where the mycelium grows out of its substrate as a solid mass, producing a sclerotia. The fruiting body of this species is rarely witnessed and only the sclerotia has a tradition of use.
Chaga dwells primarily in birch forests of the far Northern latitudes (45°N-50°N) , so much of its tradition of use comes from Russia, as well as Northern Europe and Asia. The complex biochemistry in Chaga is a response to the environmental stressors it is adapted to, including cold, pathogens and competition for nutrients with other microbial species . Though it likely has been utilised for longer, the first documented medicinal use we have dates to Avicenna (circa 1000 CE) . Traditionally Chaga, harvested only from living trees, is utilised for a wide range of health concerns including [4,5]:
Gastritis, stomach upset, gastrointestinal ulceration
Cardiovascular diseases, hypertension
Periodontitis, dermatitis, psoriasis
Cancers (it is recorded that a Russian duke, Vladimir Monomakh (circa 1100 CE) utilised Chaga to resolve his lip cancer!) 
Cuts, abrasions and wounds (topical application)
Nasopharyngeal inflammation and impaired breathing (inhalant)
Chaga tea was also popular with hunters and foresters as it alleviates hunger, removes tiredness, refreshes, improves general well-being and increases work capacity . This is likely the origins of Chaga being considered an adaptogen since known adaptogens like Rhodiola and Schisandra are used for this same purpose. As we will see below, modern evidence supports much of the traditional use! Chaga is not texturally edible, so traditional Russian folk practices accessed Chaga’s health qualities via hot water extraction of crushed sclerotia, taken internally as a tea or syrup, or applied externally via bath [2,6].
Of course, like all fungi, Chaga has special beta-glucan polysaccharides that give it a special capacity to interact with our immune system. However, there are more than 200 distinct bioactive compounds that have been identified in Chaga! The most obvious of these is its melanin content, which is visible as the black colour on the surface of the sclerotia. Fungal melanin has antioxidant, probiotic, and hypoglycemic qualities at least .
Chaga also contains many bioactive terpenes: lanostane-type triterpenoids (approximately 40 of these, e.g. inotodiol, chagabusone) are mostly from the softer interior of the sclerota, while becholine-derived triterpenes are drawn from the bark of birch trees (Becholina spp.) and stored in the melanin-rich dark surface of Chaga. Interestingly, and this is not true of all medicinal fungi, the chemical content of Chaga is greatly influenced by the species of tree it grows on, and its location. As an example, French Chaga contains higher betulin and betulinic acid compared to Canadian Chaga, which is higher in inotodiol content . Birch trees (leaf and stem bark) are a traditional medicine which gives the chemistry of Chaga added interest.
Currently there are no human studies using Chaga that I have been able to find. Much of the older research is not in English. I imagine this will change soon as popularity surges and experimental data continues to flow!
Like all edible mushrooms, the fungal polysaccharides (and other components) promote immunological harmony via complex mechanisms that trickle down and affect many aspects of our health [3,6].
Part of the immune supporting effect is a substantial anti-inflammatory activity, with evidence of antiallergic and antiasthmatic qualities (meaning Chaga helps dampen down hyper-reactive immune responses). Significant inhibition of histamine-induced macrophage activity [6,8] occurs with Chaga in mice. Both Th2 and Th17 immune responses are modulated by lipophilic and lipophobic extracts, so this likely relies on the polysaccharide components. However only lipophilic compounds (i.e. inotodiol) are able to inhibit mast cells so we can assume that water-extracts are insufficient for supporting allergic responses .
Chaga is also anti-viral [6,10,11] and antimicrobial , with probiotic qualities that encourage a healthy microbiota [12,13].
Most of the scientific exploration of Chaga has been motivated by its apparent anticancer qualities. Older clinical data indicates that Chaga is beneficial in stage III & IV cancer, regardless of location, and that in these patients 3-4 weeks administration allowed reduction or termination of narcotic medications . This data has not been verified but has encouraged more mechanistic research recently! The most recent reviews declare significant and promising effects from Chaga, with direct antitumor activity in a variety of cancer cell types [3,6]. Inotodiol, for instance, exhibits anti-migration and anti-invasion activity, inducing apoptosis in human cervical cancer cells . Other aromatic compounds display some cytotoxic activity against liver cancer cell lines . The polysaccharides also induce apoptosis in a variety cancer cells and alter energy metabolism via AMPK signalling in vitro [16, 17] and demonstrating anti-metastatic effects in rodent melanoma cells .
In an animal study utilising two rat models of lung carcinoma, we witness significant tumor suppressive effects with 3 weeks of daily intake at 6 mg/kg . In mice with tumors, there was a 60% reduction in size, in those with metastasis, a 25% decrease in the number of nodules was observed. Other observations included increased tumour agglomeration and inhibition of vascularization, as well as reduced body weight and changes to body temperature.
With so many aspects to Chaga’s potential anticancer mechanisms, it is a key area of research, however Chaga appears to offer much more besides! The antioxidant support proffered by Chaga is substantial, thanks mainly to its phenolic compounds, which give it a strong hand to play in diseases linked to high oxidative stress (hence cancers, but also think cardiovascular disease, diabetes and other metabolic disorders, Alzheimer’s disease, etc.) . In one analysis of Chaga’s triterpenes, not only was significant antioxidant capacity witnessed, but there was evidence of antimutagenic (gene-protective) effects too . We also have initial data supporting organ-specific protection, for example:
Liver – protects against hepatotoxic effects of some drugs and pathogens [21,22]
Gastrointestinal tract – anti-gastric ulcer activity in rats 
Brain – antioxidant and anti-Alzheimer’s activity in vitro [24,25]
Kidney – reduces renal fibrosis in mice 
Pancreas – (see below)
A key finding is Chaga’s potential in diabetes and states of hyperglycemia. Certain specialised pentacyclic triterpenoids from Chaga exhibit potent α-glucosidase inhibition in vitro . This enzyme is found in our intestines and releases glucose from more complex sugars and starches, blocking it reduces the amount and/or rate of sugar we absorb from a meal. The antidiabetic support continues with experimental studies showing modulation of plasma glucose, insulin, leptin and many other related markers toward improved blood-sugar management [28, 29]. The organoprotective effects outlined above further protect against the complications resulting from chronic hyperglycemia, with repaired damage to kidney tissue evident in mouse models of diabetes [Wang 17], as well as pancreatic protection. Chaga alleviated chronic pancreatitis in mice , and offers protection to damaged pancreatic β-cells [3,31].
Also related to diabetes, is obesity, and it appears that Chaga helps regulate adipose tissue metabolism and differentiation , and this is demonstrated with the amelioration of obesity in rats fed a high-fat diet .
Actually, Chaga is often generalised as an adaptogen, while this may or may not be true, it is thought to improve physical stamina . We do see that polysaccharides from Chaga improve physical endurance, reducing fatigue in mice .
Chaga’s triterpenes even seem to protect against hair-loss, as traditional use in Mongolia indicates, with pro-proliferative effects on hair growth via human follicle dermal papilla cells (HFDPCs) in vitro .
Safety, Quality and Dosing
Chaga is wildcrafted, and as mentioned earlier, the chemical contents can vary dramatically with growing conditions, host species and whether or not the host tree is alive. Living trees likely provide a complex array of phytochemicals from sap which are digested and transformed by the Chaga. I recommend using Chaga Birch trees and must be harvested while the tree is still living.
While the traditional method of extraction was hot water only, to get adequate constituents this requires long extraction times due to the complexity of the Chaga matrix, which can lead to degradation of the extracted compounds. Therefore, while a water infusion is certainly medicinal, the best results come from an ethanol/water extract that results in a more comprehensive range of medicinal compounds .
Chaga appears to be very safe , however I recommend not taking high doses over long periods as it is high in oxalates which can accumulate and cause damage. I recommend the equivalent of 3-6 g of dry Chaga, daily.
I recommend Chaga as a daily well-being tonic, and in combination with other herbs and mushrooms to people with high oxidative damage driving their disease states, particularly for diabetes, cardiovascular disease, and to those at risk of dementia, organ damage, and cancer development. It is likely to also be helpful for asthma and allergy, psoriasis and to improve immune function generally.
If you would like a more in-depth and clinically focussed take on this excellent medicinal fungus, see my Chaga Monograph [COMING SOON!].
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