The health benefits of shiitake mushrooms lies in the fact that they contain high levels of vitamins and minerals, proteins, fiber and some anti-tumor substances, according to SFGate. These benefits are more potent when individuals eat the mushrooms raw.
Four raw shiitake mushrooms have 26 calories and are very low in fat; however, they have 2 grams each of protein and dietary fiber. The same number of dried and cooked shiitakes have 40 calories but are lower in protein and fiber.
Shiitake mushrooms are also a good source of the B vitamins, including riboflavin, niacin and vitamin B6. In this case, dried shiitake mushrooms have a bit more riboflavin than raw shiitakes. Shiitake mushrooms also contain a good amount of folate, pantothenic acid and choline and a small amount of vitamin C, notes Self.com.
Shiitake mushrooms, raw and dried, also have an impressive quantity of phosphorus, potassium and magnesium. They are rich in selenium, says Self.com.
One study indicated that shiitake mushrooms stop the growth of tumors in mice. The mice had melanoma, a type of skin cancer, and powdered shiitake extract stimulated the production of T-cells that attacked melanoma. The lentinan in shiitake mushrooms also protected the mice from colon cancer, according to About.com. Lentinan is substance that supports the immune system.