Mushrooms are amazing. Lions Mane, Turkey Tail, Reishi … all seem to have very powerful impact on human immune systems.
Chaga is a fungus, not necessarily a “mushroom”. Mushrooms are fungus, but not all fungus are mushrooms.
Chaga grows on birch trees. A country Soviet Doctor “discovered” it when he noticed people in certain local peasant villages never contracted any form of cancer. Turns out they all drank Chaga tea.
Here is a bit more on the link between Chaga and cancer treatment. From the article:
“He could not imagine any greater joy than to go away into the woods for months on end, to break off this chaga, crumble it, boil it up on a campfire, drink it and get well like an animal…. Just as a dog goes to search for some mysterious grass that will save him….” (from Cancer Ward, by Alexander Solzhenitsyn)