What Is Ergothioneine? Ergothioneine (ERGO) is a unique naturally occurring amino acid produced by mushrooms, yeast, and some types of bacteria. It is unique because it behaves much like a vitamin in humans. Vitamins are essential for humans to ingest because we cannot make them in the body, and they are required in critical chemical reactions. While not considered a vitamin (yet), the importance of ERGO to human cellular metabolism is evident because our bodies have a cell membrane protein that is specific to transporting ERGO into cells. The presence of this transport protein signifies that ERGO is a critical component of cellular function. What Does Ergothioneine Do? Once incorporated into cells, ERGO exerts several biological actions that protect and enhance cellular function, including acting as an antioxidant, inflammation regulator, and detoxification aid. Emerging evidence shows that diets rich in ERGO exert these protective effects and promote longevity. For these reasons, ERGO has been referred to as the "longevity vitamin." What Makes Ergothioneine Important? ERGO is a thiol, meaning it is a sulfur-containing compound. Some of its antioxidant and potential antiaging effects are similar to other thiol-containing compounds, such as glutathione and coenzyme Q10. ERGO is different because it is a much smaller molecule distributed throughout the body and all the compartments of the cells, including the internal cellular environment (cytoplasm) and within mitochondria (the energy-producing compartment of cells). A clinical study in humans has shown that taking ERGO as a dietary supplement raises blood levels of ERGO, improves thiol status, and may increase antioxidant status to produce various health benefits.