L-ergothioneine (EGT) is a rare natural chiral amino acid. EGT mainly comes from plants such as mushrooms, broccoli, Brussels sprouts, and certain bacteria, but cannot be synthesized by the animal body itself. It can only be absorbed from food and accumulated in tissues and cells. Since the discovery of ergot in animal organs and tissues, scientists have conducted a lot of research work and found that ergot can effectively eliminate free radicals that cause skin aging, protect cell membranes and mitochondrial membranes from oxidative damage, protect cells, and resist UV radiation. Therefore, it has wide application prospects in industries such as food, cosmetics, functional foods, and biomedicine.