Reishi mushrooms (Ganoderma lucidum) have been a part of some traditional medicine practices for more than 2,000 years.
According to one review article, reishi mushrooms contain polysaccharides, peptides, and triterpenoids, which may provide some of their health benefits. They also contain dietary fiber and various minerals, vitamins, and amino acids.
People grind them into powder or use extracts to make supplements and other products. While their use is widespread, the evidence supporting any benefits is still lacking.
Reishi mushroom is a fungus. Some people describe it as "tough" and "woody" with a bitter taste. The above-ground part and portions of the below-ground parts are used as medicine.
Reishi mushroom is used for cancer, boosting the immune system to prevent or treat infections, and for many other reasons, but there is no good scientific evidence to support these uses.
How does it work?
Reishi mushroom contains chemicals that seem to have activity against tumors (cancer) and beneficial effects on the immune system.