Natural Moisturizing Factor (NMF) is a mixture of small, water-binding molecules found inside corneocytes — amino acids, urea, lactate and pyrrolidone carboxylic acid (PCA). It is the skin's own natural moisturising system.
NMF is largely formed by the breakdown of a protein called filaggrin, which bundles keratin fibres in the epidermis and degrades into NMF components as cells mature. NMF production is thus directly linked to the skin's normal renewal cycle.
Because NMF is water-soluble, frequent washing, harsh cleansers and long hot showers can wash it away, contributing to dryness. Gentle cleansing and barrier-supported care help preserve both NMF and lipid structure.