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) [1], 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 [2]. Though it likely has been utilised for longer, the first documented medicinal use we have dates to Avicenna (circa 1000 CE) [3]. 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
Diabetes
Periodontitis, dermatitis, psoriasis
Cancers (it is recorded that a Russian duke, Vladimir Monomakh (circa 1100 CE) utilised Chaga to resolve his lip cancer!) [5]
Cuts, abrasions and wounds (topical application)
Nasopharyngeal inflammation and impaired breathing (inhalant)
General well-being
Chaga tea was also popular with hunters and foresters as it alleviates hunger, removes tiredness, refreshes, improves general well-being and increases work capacity [4]. 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].
Medicinal Application
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 [6].
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 [7]. 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 [9].
Chaga is also anti-viral [6,10,11] and antimicrobial [5], 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 [5]. 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 [14]. Other aromatic compounds display some cytotoxic activity against liver cancer cell lines [15]. 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 [18].
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 [19]. 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.) [2]. In one analysis of Chaga’s triterpenes, not only was significant antioxidant capacity witnessed, but there was evidence of antimutagenic (gene-protective) effects too [20]. 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 [23]
Brain – antioxidant and anti-Alzheimer’s activity in vitro [24,25]
Kidney – reduces renal fibrosis in mice [26]
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 [27]. 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 [30], 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 [6], and this is demonstrated with the amelioration of obesity in rats fed a high-fat diet [32].
Actually, Chaga is often generalised as an adaptogen, while this may or may not be true, it is thought to improve physical stamina [5]. We do see that polysaccharides from Chaga improve physical endurance, reducing fatigue in mice [33].
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 [34].
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 [2].
Chaga appears to be very safe [5], 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!].
References
[1] Hu H, Zhang Z, Lei Z, et al. Comparative study of antioxidant activity and antiproliferative effect of hot water and ethanol extracts from the mushroom Inonotus obliquus. J Biosci Bioeng. 2009 Jan;107(1):42-8.
[2] Hwang AY, Yang SC, Kim J, et al. Effects of non-traditional extraction methods on extracting bioactive compounds from chaga mushroom (Inonotus obliquus) compared with hot water extraction. LWT. 2019 Aug 1;110:80-4.
[3] Balandaykin ME, Zmitrovich IV. Review on Chaga Medicinal Mushroom, Inonotus obliquus (Higher Basidiomycetes): Realm of Medicinal Applications and Approaches on Estimating its Resource Potential. Int J Med Mushrooms. 2015;17(2):95-104.
[4] Shashkina MY, Shashkin PN, Sergeev AV. Chemical and medicobiological properties of chaga. Pharmaceutical Chemistry Journal. 2006 Oct 1;40(10):560-8.
[5] Shikov AN, Pozharitskaya ON, Makarov VG, et al. Medicinal plants of the Russian Pharmacopoeia; their history and applications. J Ethnopharmacol. 2014 Jul 3;154(3):481-536.
[6] Duru KC, Kovaleva EG, Danilova IG, et al. The pharmacological potential and possible molecular mechanisms of action of Inonotus obliquus from preclinical studies. Phytother Res. 2019 Aug;33(8):1966-1980.
[7] Géry A, Dubreule C, André V, Rioet al. Chaga (Inonotus obliquus), a Future Potential Medicinal Fungus in Oncology? A Chemical Study and a Comparison of the Cytotoxicity Against Human Lung Adenocarcinoma Cells (A549) and Human Bronchial Epithelial Cells (BEAS-2B). Integr Cancer Ther. 2018 Sep;17(3):832-843.
[8] Javed S, Mitchell K, Sidsworth D, et al. Inonotus obliquus attenuates histamine-induced microvascular inflammation. PLoS One. 2019 Aug 22;14(8):e0220776.
[9] Nguyet TMN, Lomunova M, Le BV, et al. The mast cell stabilizing activity of Chaga mushroom critical for its therapeutic effect on food allergy is derived from inotodiol. Int Immunopharmacol. 2018 Jan;54:286-295.
[10] Seo DJ, Choi C. Inhibition of murine norovirus and feline calicivirus by edible herbal extracts. Food and environmental virology. 2017 Mar 1;9(1):35-44.
[11] Tian J, Hu X, Liu D, et al. Identification of Inonotus obliquus polysaccharide with broad-spectrum antiviral activity against multi-feline viruses. Int J Biol Macromol. 2017 Feb;95:160-167.
[12] Burmasova MA, Utebaeva AA, Sysoeva EV, et al. Melanins of Inonotus Obliquus: Bifidogenic and Antioxidant Properties. Biomolecules. 2019 Jun 24;9(6):248.
[13] Hu Y, Teng C, Yu S, et al. Inonotus obliquus polysaccharide regulates gut microbiota of chronic pancreatitis in mice. AMB Express. 2017 Dec;7(1):39.
[14] Zhang SD, Yu L, Wang P, et al. Inotodiol inhibits cells migration and invasion and induces apoptosis via p53-dependent pathway in HeLa cells. Phytomedicine. 2019 Jul;60:152957.
[15] Zou CX, Zhang YY, Bai M, et al. Aromatic compounds from the sclerotia of Inonotus obliquus. Nat Prod Res. 2019 Oct 15:1-4.
[16] Jiang S, Shi F, Lin H, et al. Inonotus obliquus polysaccharides induces apoptosis of lung cancer cells and alters energy metabolism via the LKB1/AMPK axis. Int J Biol Macromol. 2020 May 15;151:1277-1286.
[17] Tsai CC, Li YS, Lin PP. Inonotus obliquus extract induces apoptosis in the human colorectal carcinoma's HCT-116 cell line. Biomed Pharmacother. 2017 Dec;96:1119-1126.
[18] Lee KR, Lee JS, Lee S, et al. Polysaccharide isolated from the liquid culture broth of Inonotus obliquus suppresses invasion of B16-F10 melanoma cells via AKT/NF-κB signaling pathway. Mol Med Rep. 2016 Nov;14(5):4429-4435.
[19] Arata S, Watanabe J, Maeda M, et al. Continuous intake of the Chaga mushroom (Inonotus obliquus) aqueous extract suppresses cancer progression and maintains body temperature in mice. Heliyon. 2016 May 12;2(5):e00111.
[20] Ham SS, Kim SH, Moon SY, et al. Antimutagenic effects of subfractions of Chaga mushroom (Inonotus obliquus) extract. Mutat Res. 2009 Jan;672(1):55-9.
[21] Li Z, Mei J, Jiang L, et al. Chaga Medicinal Mushroom, Inonotus obliquus (Agaricomycetes) Polysaccharides Suppress Tacrine-induced Apoptosis by ROS-scavenging and Mitochondrial Pathway in HepG2 Cells. Int J Med Mushrooms. 2019;21(6):583-593.
[22] Xu L, Sang R, Yu Y, et al. The polysaccharide from Inonotus obliquus protects mice from Toxoplasma gondii-induced liver injury. Int J Biol Macromol. 2019 Mar 15;125:1-8.
[23] Xin X, Qu J, Veeraraghavan VP, et al. Assessment of the Gastroprotective Effect of the Chaga Medicinal Mushroom, Inonotus obliquus (Agaricomycetes), Against the Gastric Mucosal Ulceration Induced by Ethanol in Experimental Rats. Int J Med Mushrooms. 2019;21(8):805-816.
[24] Zou CX, Hou ZL, Bai M, et al. Highly modified steroids from Inonotus obliquus. Org Biomol Chem. 2020 May 27;18(20):3908-3916.
[25] Han Y, Nan S, Fan J, et al. Inonotus obliquus polysaccharides protect against Alzheimer's disease by regulating Nrf2 signaling and exerting antioxidative and antiapoptotic effects. Int J Biol Macromol. 2019 Jun 15;131:769-778.
[26] Chou YJ, Kan WC, Chang CM, et al. Renal Protective Effects of Low Molecular Weight of Inonotus obliquus Polysaccharide (LIOP) on HFD/STZ-Induced Nephropathy in Mice. Int J Mol Sci. 2016 Sep 13;17(9):1535.
[27] Ying YM, Yu HF, Tong CP, et al. Spiroinonotsuoxotriols A and B, Two Highly Rearranged Triterpenoids from Inonotus obliquus. Org Lett. 2020 May 1;22(9):3377-3380.
[28] Wang C, Li W, Chen Z, et al. Effects of simulated gastrointestinal digestion in vitro on the chemical properties, antioxidant activity, α-amylase and α-glucosidase inhibitory activity of polysaccharides from Inonotus obliquus. Food Res Int. 2018 Jan;103:280-288.
[29] Wang J, Hu W, Li L, et al. Antidiabetic activities of polysaccharides separated from Inonotus obliquus via the modulation of oxidative stress in mice with streptozotocin-induced diabetes. PLoS One. 2017 Jun 29;12(6):e0180476.
[30] Hu Y, Sheng Y, Yu M, et al. Antioxidant activity of Inonotus obliquus polysaccharide and its amelioration for chronic pancreatitis in mice. Int J Biol Macromol. 2016 Jun;87:348-56.
[31] Sim YC, Lee JS, Lee S, et al. Effects of polysaccharides isolated from Inonotus obliquus against hydrogen peroxide-induced oxidative damage in RINm5F pancreatic β-cells. Mol Med Rep. 2016 Nov;14(5):4263-4270.
[32] Wu T, Shu Q, Yang K, et al. Ameliorating effects of Inonotus obliquus on high fat diet-induced obese rats. Acta Biochim Biophys Sin (Shanghai). 2015 Sep;47(9):755-7.
[33] Zhang CJ, Guo JY, Cheng H, Li L, Liu Y, Shi Y, Xu J, Yu HT. Spatial structure and anti-fatigue of polysaccharide from Inonotus obliquus. Int J Biol Macromol. 2020 May 15;151:855-860.
[34] Sagayama K, Tanaka N, Fukumoto T, et al. Lanostane-type triterpenes from the sclerotium of Inonotus obliquus (Chaga mushrooms) as proproliferative agents on human follicle dermal papilla cells. J Nat Med. 2019 Jun;73(3):597-601.