Identification
A black cracked sterile conk on live birch; inside — orange-brown corky flesh. Not a cap mushroom.
What's inside
Betulinic acid (metabolized from birch betulin), melanin, polysaccharides; ORAC antioxidant values are famously high in laboratory measures.
Evidence
Mostly preclinical: anticancer and immunomodulatory effects in vitro and in animal models. Human evidence is sparse — no established therapy.
In practice — cautions
- Contains oxalates — heavy chronic use is a documented kidney-stone risk.
- Harvest from living birch only; leave part of the conk for regrowth.