Ergothioneine is an antioxidant amino acid that occurs naturally in the body, however, we can’t synthesize it, so we need to obtain it from our diet. Foods such as mushrooms (the darker, the better), kidney, liver, red and black beans and oat bran are highest contributors of this nutrient. Its claim to fame is that it is an effective antioxidant and anti-inflammatory. In skin care products, ergothioneine has a registered derivative called thioneine. Very few products are available in market containing this ingredient, but stay tuned.