From the brand:

L-ergothioneine is an amino acid and antioxidant primarily found throughout the body that we can only obtain through food, with mushrooms and fungi being the highest source. Shiitake and Oyster mushroom, apart from containing beneficial beta-glucans, contain some of the highest amounts of ergothioneine. Studies suggest that as we age, L-ergothioneine levels in the body decrease and supplementing with ergothioneine could help mitigate age related ailments.

• Includes Certified Organic mushrooms
• Gluten-Free, Non-GMO, Vegan
• No added starch, mycelium, or grain of any kind
• 300mg pills, 60 capsules, 60 servings
• Verified for quality at accredited 3rd party labs