Ergothioneine is a naturally occurring antioxidant amino acid that the human body cannot make on its own and instead absorbs from dietary sources like mushrooms, then actively concentrates in skin and other tissues through a dedicated transporter.
Because the body works specifically to hold onto it, researchers consider ergothioneine one of the more biologically important antioxidants naturally found in skin.
Laboratory research has found that ergothioneine protects skin cells against UV induced oxidative damage, in part by activating one of the body's own master antioxidant defense pathways. Human research on oral ergothioneine supplements has also measured improvements in several skin health markers
Ergothioneine References
Ergothioneine Protects Against UV Induced Oxidative Stress Through the PI3K/AKT/Nrf2 Signaling Pathway, Clinical, Cosmetic and Investigational Dermatology, 2024
L-Ergothioneine Protects Skin Cells against UV Induced Damage, A Preliminary Study
Our team reviews ingredient research and uses up-to-date evidence to rate ingredients based on the categories below.
Best
Ingredients with the most rigorous and convincing evidence. These are the standouts backed by consistent findings across independent, peer reviewed clinical research.. When we call an ingredient Best, it has earned that distinction through genuine, reproducible proof that it improves skin.
Good
Reliable, well tolerated ingredients that do their job without complaint. They may not carry the headline benefits of a Best rated active, but they hydrate, stabilize a formula, or support the ingredients around them in ways that make a real difference in how a product performs and feels.
Average
Ingredients that are perfectly safe and serve a clear function, typically as an emollient, thickener, or filler, but do not offer any meaningful skin benefit beyond that basic job. Not a red flag, just not a reason to choose one product over another.
Bad/Worst
Ingredients with documented potential to irritate skin, disrupt the barrier, or trigger sensitization in some users, often synthetic fragrance, drying forms of alcohol, or certain essential oils. Not automatically a dealbreaker for every skin type, but worth knowing about before you commit to a product.
