The barrier function of skin depends on the stratum corneum extracellular lipid matrix, which includes ceramides, cholesterol, and free fatty acids. Smaller amounts of cholesterol sulfate and cholesteryl oleate may be present. Applied topically, cholesterol in cosmetics can help maintain the skin’s normal function. It is also a stabilizer, emollient, and water-binding agent. 
- Norlén L, Gil I, Simonsen A, Descouts P. Human stratum corneum lipid organization as observed by atomic force microscopy on Langmuir-Blodgett films. J Struct Biol. 2007;158(3):386-400.
natural moisturizing factor (NMF)