Aside from being a delicious culinary species, Shiitake is also a extensively studied medicinal species relative to a variety of conditions.
Shiitake has excellent nutritional value: It contains proteins(25.9% dry weight), lipids(primarily linoleum acid), carbohydrates(67% dry weight), soluble and insoluble fiber, minerals(especially calcium), and vitamins B2 and C. Shiitake has high amounts of ergosterol, a provitamin that converts to vitaminD2 in the presence of sunlight.
There is an immense volume of data available on this mushroom.
Shiitake is an Adaptogen, and has been used to treat many cancers, Hepatitis B, HIV, high cholesterol, anxiety, allergies, and Candidiasis. In Chinese Medicine, it is said to tonify the Qi and the Blood.
The main bioactive constituents of shiitake are polysaccharides, but it also contains triterpenes and ergothioneine, a potent antioxidant. *