Natural Moisturizing Factors (NMF's) and Surface Lipids

The most important substance for the suppleness of the skin is water. In young skin, water content of the upper horny layer accounts for between 10 and 20 percent of the water in the entire body. The skin receives its moisture from water from the deeper layers (transepidermal water) and from normal sweat secretions. Various factors, such as a lack of moisture-binding substances or extremely low humidity, can lead to an increased loss of moisture to the environment. More exposed areas of the body, such as the face and hands, are more prone to this. Natural Moisturizing Factors (NMF's), body's own substances derived from sweat and sebaceous oils (e.g. urea), as well as the cornification process (e.g. pyrrolidine carboxylic acid), help skin retain water in the horny layer. Without natural moisturizing factors, water would evaporate leaving the skin dry and cracked.