Given the recent marketing hype around ceramide skincare products, you might think “ceramides” are cutting-edge — a new, trendy, must-try beauty ingredient. But that’s only partially true. The substance is pretty popular right now, but in reality, ceramides couldn’t be any older or more ordinary. They’re built right into your skin.

“Ceramides are a type of fat in the skin which hold the skin cells together and prevent the loss of water from the skin’s surface,” Dr. Lily Talakoub, M.D., F.A.A.D, a board-certified dermatologist with McClean Dermatology, tells The Zoe Report. “They are our skin’s natural moisturizers.”