Natural Moisturizing Factor (NMF)

Natural moisturizing factor, or NMF, is a collection of small water-soluble compounds found inside the cells of the stratum corneum that attract and hold water. It is what keeps the outer skin layer hydrated, supple and able to function as a barrier.

NMF is a mixture rather than a single ingredient. It includes amino acids, pyrrolidone carboxylic acid (as in sodium PCA), lactates, urea, sugars and various salts. Much of it is produced as the protein filaggrin is broken down during the natural maturation of skin cells. These components act as built-in humectants, drawing water from deeper layers and the environment and binding it within the corneocytes so the surface stays flexible.

When NMF levels drop, through aging, over-cleansing, low humidity or barrier damage, the stratum corneum holds less water and skin can feel tight, look dull and become prone to flaking. This is why many moisturizers include NMF-mimicking ingredients such as sodium PCA, urea, amino acids and lactates to top up the skin's own water-binding system. Supporting the barrier so that natural NMF production continues, rather than relying on humectants alone, is generally the more sustainable approach.