Natural Moisturizing Factor (NMF), Explained: What Skin Makes From Filaggrin, Why Humidity Moves It, and Which Moisturizer Ingredients Copy It

What NMF actually is: small molecules inside the cells

NMF is not a single ingredient. It is a collection of free amino acids and their derivatives, plus salts, sugars, lactic acid and urea, packed inside the flattened corneocytes of the stratum corneum. One review puts it at roughly 20 to 30 percent of the dry weight of the stratum corneum. Because the molecules are small and attract water, they keep the cells hydrated without any help from the lipid layers between them.

Where it comes from: a protein called filaggrin

Skin does not absorb NMF from outside; it manufactures it. A large precursor protein, profilaggrin, is broken down into filaggrin as cells mature, and filaggrin is then degraded step by step into amino acids and derivatives such as PCA (pyrrolidone carboxylic acid) and urocanic acid. The review states this breakdown supplies 70 to 100 percent of the free amino acids in the stratum corneum. So NMF is the end product of a process, which is why it responds to what is happening in the skin.

Humidity changes where the breakdown happens

The enzymes that break down filaggrin need water to work, but not too much. In humid air the breakdown occurs almost at the outermost surface, while in low humidity it moves to deeper layers. Water activity inside the cells has to stay in a narrow range: too much stabilizes filaggrin, too little stops the enzymes. That is one explanation for why skin can feel tight in winter heating even when you drink plenty of water.

When the gene is different: fewer NMF at every depth

Loss-of-function mutations in the filaggrin gene affect roughly 9 percent of people of European descent. Carriers show significantly lower NMF levels at all depths of the stratum corneum and higher transepidermal water loss than non-carriers, and the mutations predispose people to atopic dermatitis. This is a medical finding, not a skincare problem to solve with a cream. If you have persistent dry, inflamed or itchy patches, see a dermatologist rather than treating it as a routine issue.

Which moisturizer ingredients copy NMF

Several NMF components are sold directly. Urea has been used in skin products since 1943, and its role at different strengths is covered in our urea guide. Lactate was first reported as a therapy in 1946 and is described as stimulating ceramide synthesis. PCA, usually listed as sodium PCA, is the most abundant single NMF component, and amino acids appear in many formulas. Glycerin is not part of NMF, but it plays a similar water-binding role, as in the glycerin study summary.

What an NMF label does not tell you

A product labeled "with NMF" may contain one or two of these molecules, not the full natural mix, and the label rarely shows the percentage. Composition tables vary between studies; one commonly cited table lists amino acids as the largest share, followed by urea, PCA and lactate, but the exact split depends on how the skin was sampled. So treat any single number as an illustration. What matters more is whether the product combines a humectant with an occlusive layer, as explained in humectants, occlusives and emollients.

How to use this in a routine

Water-binding molecules work best on slightly damp skin and need a lipid layer on top to slow evaporation. If your barrier is stressed, a barrier-focused routine matters more than adding another humectant; see skin barrier repair explained. Cosmetics cannot treat or prevent medical conditions. Do a patch test on the inner forearm before using a new product, and talk to a dermatologist about persistent dryness, eczema-like rashes or any suspected filaggrin-related condition. Sources: a Practical Dermatology review of NMF and filaggrin and published composition tables, checked October 2026.