Chaga mushroom
The Chaga mushroom (Inonotus obliquus), also known as tinder mushroom, is a fungus in Hymenochaetaceae family. It is a parasitic fungus of the Birch and other trees. The sterile conk is irregularly formed and has the appearance of burnt charcoal. It causes the tree's death in 5-7 years, and is known as "birch cancer" in Russia, but like many medicinal mushrooms contains many of its own anti-tumor compounds.

# Medicinal use
The antimutagenic action of the molecules found in the white part of birch bark where chaga feeds inhibit free-radical oxidation; and, induce the production of interferons, which help induce DNA repair. The substances, contained in white part of birch bark contribute to the decrease of hypoxia and to increase of the stability of organism to the oxygen deficiency, being antihypoxant correcting the metabolism of cells. The anti-cancer properties of betulin or betulinic acid, a chemical isolated from birch trees, is now being studied for use as a chemotherapeutic agent.  Chaga contains large amounts of betulinic acid in a form that can be ingested orally, and it also contains the full spectrum of immune-stimulating phytochemicals found in other medicinal mushrooms such as maitake mushroom and shiitake mushroom. Since the 16th century, Chaga Mushroom has been used in folk medicine and the botanical medicine of the Eastern European countries as a remedy for cancer and gastritis, ulcers, tuberculosis (TB) of the bones. In 1958, scientific studies in Finland and Russia found this mushroom provided an epochal effect in breast cancer, liver cancer, uterine cancer, and gastric cancer, as well as in hypertension and diabetes. Herbalist David Winston maintains that it is the strongest anti-cancer medicinal mushroom.

# Research
In 1998 there was a study in Poland that demonstrated Chaga's inhibiting effects on tumor growth. Noda et. al found that betulin seems to work highly selectively on tumor cells because the interior pH of tumor tissues is generally lower than that of normal tissues, and betulinic acid is only active at those lower levels. Fulda et al. found in 1997 that once inside the cells, betulinic acid induces apoptosis (programmed cell death) in the tumors.  In 2005 there was a study done at Department of Medical Nutrition in South Korea. The Chaga Mushroom was evaluated for their potential for protecting against oxidative damage to DNA in human lymphocytes. The study found that the polyphenolic extract protected these cells against hydrogen peroxide-induced oxidative stress. Another study that year found the endo-polysaccharide of Chaga produced indirect anti-cancer effects via immuno-stimulation. The mycelial endo-polysaccharide of I. obliquus was identified as a candidate for use as an immune response modifier and indicate that the anti-cancer effect of endo-polysaccharide is not directly tumorcidal but rather is immuno-stimulating. It has also been demonstrated as anti-inflammatory. Saitoh Akiko published on the antimutagenic effects of Chaga in 1996, and Mizuno et al. published on the anti tumor and hypoglycemic activities of the polysaccharides from the sclerotia and mycelia of Chaga.
Chaga grows in birch forests of Russia, Korea, Eastern Europe, Northern areas of the United States and in the North Carolina mountains.