High levels of the health-relevant antioxidant selenoneine identified in the edible mushroom Boletus edulis.

Background: Selenoneine, the selenium analogue of the sulfur antioxidant ergothioneine, has been ascribed a multitude of beneficial health effects. Natural nutritional sources for this selenium species are, hence, of high interest. So far marine fish is the only significant selenoneine source consumed by larger parts of the population worldwide.