<img src="https://example.com/hero-ergothioneine.jpg&quot; alt="Hero image of a bright green mushroom field bathed in morning light – a natural source of ergothioneine” /> Alt text: Sun‑lit mushroom field illustrating the primary dietary source of ergothioneine. What Is Ergothioneine? Ergothioneine (EGT) is a naturally occurring thiol‑containing amino acid first isolated from the mushroom Claviceps purpurea in 1909. Unlike…