Retinol disassociates into retinoic acid, which is the biologically active form of vitamin A, by enzymes beneath the surface of the skin. Retinol stimulates the skin’s natural rebuilding process by supporting the expression of glycosaminoglycans, chemicals that bind to water molecules. This binding of water results in desirable, visible changes, such as firmer skin with a more even tone and texture, and fewer lines and wrinkles.