What Is NMF (Natural Moisturizing Factor)? The Stratum Corneum's Internal System
Key Facts
- 🔬 NMF makes up roughly 10-15% of a healthy stratum corneum's dry weight; it's derived from filaggrin proteolysis
- 🧬 Pyrrolidone carboxylic acid (PCA) makes up 12% of NMF and holds moisture through its strong humectant property
- 📊 NMF loss raises TEWL by 30-50%; aggressive cleansing measurably lowers NMF levels within 30 minutes
- 🛡️ Urea (7% of NMF) preserves corneocyte integrity, delivers an antimicrobial effect, and prevents hyperkeratosis
- ⚡ Aging, atopic dermatitis, frequent face washing, and low-humidity environments are the factors that lower NMF the most
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What Is NMF? Its Components and Origin
Natural Moisturizing Factor (NMF) is a collection of water-soluble, low-molecular-weight components found within the corneocytes of the stratum corneum. These components are released when the filaggrin protein is broken down by proteases. NMF's approximate composition is: amino acids 40%, pyrrolidone carboxylic acid (PCA) 12%, lactate 12%, urea 7%, ammonia and creatine 1.5%, ions like Ca, Mg, Na, K, and phosphate 18.5%, and organic acids from citrate and formate 8.5%.
The Filaggrin Connection
Filaggrin (filament aggregating protein) is synthesized as profilaggrin in the granular layer and undergoes proteolysis during the transition into the stratum corneum. Its breakdown products form NMF's components. In individuals with atopic dermatitis carrying an FLG gene mutation, NMF production is seriously disrupted, and this is the molecular basis of that barrier dysfunction.
NMF Loss: Causes and Consequences
Factors that lower NMF: (1) Sodium lauryl sulfate (SLS)-containing soaps and aggressive detergents measurably lower NMF within 30 minutes. (2) Low-humidity environments (<30% RH) speed up the evaporation of NMF components. (3) UV damage disrupts filaggrin breakdown, reducing NMF production. (4) Atopic dermatitis and an FLG mutation.van Smeden et al., 2014 (5) Aging — past age 70, NMF level drops to 50-60% of a young adult's.
Its Effect on TEWL
NMF's primary function is binding water; this bound water regulates the stratum corneum's flexibility and desquamation rate. With NMF loss, free water evaporates, TEWL rises, corneocytes become stiff and brittle, and a visibly dry, flaky appearance results.
Supporting NMF: Topical Strategies
Topical NMF support works through three approaches: (1) Formulations directly containing NMF components — moisturizers containing urea, lactate, PCA, and amino acids. (2) Actives that support filaggrin synthesis — niacinamide and ceramide upregulate filaggrin expression. (3) Preventing NMF loss — occlusive ingredients (petrolatum, shea butter) slow water loss and prevent NMF from evaporating.
Urea: NMF's Most Valuable Component
"Creams containing 5-10% urea both directly replenish NMF and regulate keratinocyte desquamation. With its mild keratinolytic property, it delivers dramatic benefit in dry, hyperkeratotic skin. 5% urea has been shown to reduce TEWL by 22% over 4 weeks."
The CIRÈLL Perspective: Moisturizing from Within
In CIRÈLL's view, ceramide repairs the stratum corneum's outer lipid wall while NMF components fill the internal water reserve. Supporting these two layers together delivers ideal barrier moisture balance. Layering a ceramide cream with a urea/PCA-containing serum or toner is built on this principle. In atopic and older skin with active NMF disruption, urea-containing formulations become the first-line ingredient.Draelos, 2018
What Do These Signs Mean for You?
Science explains how the skin works — but you likely came to this page with a specific question. We've matched the most common signs and the reason behind them here:
NMF components (amino acids, PCA) form the moisture reserve; their deficiency leads to rapid moisture loss.
Damage to tight junctions increases permeability, leaving the barrier more exposed to the irritating effect of AHA/BHA.
Filaggrin mutations directly affect barrier integrity; ceramide support partially closes this gap.
Irregularity on the stratum corneum's surface negatively affects how makeup holds and looks.
Topical Strategies for Rebuilding NMF
The Limits of Topically Supporting NMF Components
Natural moisturizing factor (NMF) forms within the stratum corneum through the proteolytic breakdown of filaggrin, which is why it can't be fully replaced topically. But NMF's main components — free amino acids, PCA (pyroglutamic acid), urea, lactate, and inorganic salts — can be delivered to the stratum corneum through topical formulations. These components reduce the practical effects of NMF deficiency by increasing the stratum corneum's hydration capacity; but this approach doesn't revive the existing NMF production mechanism.
The most evidence-backed active for topically applying NMF components is urea: at 5-10% concentration, it shows a keratolytic and humectant effect, both softening corneocyte cohesion and providing intercorneocyte hydration. PCA-containing formulations, meanwhile, are valuable for amino-acid-based NMF support. When these actives are used together with ceramide-containing formulations, they support the stratum corneum's hydration capacity from two directions.
Approaching Low NMF in Cases of Filaggrin Loss
In individuals carrying a filaggrin gene mutation (at high risk of atopic dermatitis), NMF production is permanently low; this group's topical NMF-support strategy needs to be more systematic. Long-term use of urea- and amino-acid-containing formulations, combined with a ceramide-forward moisturizer, most effectively compensates for the barrier gap in this group. Probiotic/postbiotic support can also help preserve microbiome balance, which may indirectly affect filaggrin expression.
CIRÈLL barrier formulations offer a stratum corneum hydration support system that contains NMF components alongside ceramide. This integrated approach builds a comprehensive barrier care framework that supports both of NMF's core functions — moisture retention and its antimicrobial pH contribution.
Conclusion
NMF (Natural Moisturizing Factor) is the collective term for the water-binding components found in the stratum corneum; made up of PCA, urea, amino acids, and organic acids, it forms the skin's internal moisture reserve.
Understanding the stratum corneum's molecular structure is the foundation for choosing the right barrier support. The CIRÈLL Biomimetic TriBarrier system supports NMF components and ceramide lipids together, delivering comprehensive barrier repair.
Frequently Asked Questions
What should I do to increase NMF?
Avoid aggressive cleansers, use a moisturizer containing urea + PCA, and increase moisturizer use in low-humidity environments.
Does urea burn the skin?
At concentrations under 10%, it causes almost no irritation; concentrations of 40%+ require caution in sensitive areas due to their keratinolytic effect.
What's the biggest habit that lowers NMF?
Frequent, aggressive face washing; SLS-containing soaps reduce NMF at a dramatic rate.
Does hyaluronic acid replace NMF?
HA works through a different mechanism — it holds moisture at the surface; it doesn't fully replace NMF's intracellular water-binding function. Using them together is more effective.
Is NMF different in babies compared to adults?
Yes; baby skin starts out in a transitional period with low NMF and ceramide levels — this is why baby skin's barrier is especially fragile.
What should you look for when choosing a ceramide-containing product?
Formulations that combine Ceramide NP, AP, or EOP types with cholesterol and free fatty acids at physiological ratios should be preferred. Ceramide alone is less effective.
Can oily skin use ceramide?
Yes. Oily skin produces sebum, but this doesn't make up for a stratum corneum lipid deficiency. Light, gel-based ceramide formulations are suitable for oily and barrier-compromised skin.
How often should ceramide products be applied?
Regular use morning and evening after cleansing is recommended. Clinical studies report TEWL reduction and barrier improvement within 4-6 weeks with twice-daily application.
Mine Ekber
CIRÈLL Formulation & Content Team
A content editor who works with the CIRÈLL R&D team on skin barrier physiology. The scientific claims on this page are based on peer-reviewed sources verified through PubMed/NCBI; the source list is below.
Scientific Sources
- van Smeden J, et al. The importance of free fatty acid chain length for the skin barrier function in atopic eczema patients. Exp Dermatol. 2014.
- Draelos ZD. The science behind skin care: Moisturizers. J Cosmet Dermatol. 2018.