Scientifically grounded · Dermatology-informed · No marketing claims
Definition
The Natural Moisturizing Factor (NMF) is a collection of water-soluble, hygroscopic compounds found inside the corneocytes of the stratum corneum — your skin's outermost layer. Composed of amino acids, sodium PCA, sodium lactate, betaine, and other moisture-binding substances, NMF is your skin's own built-in humectant system. When it is depleted, no amount of surface moisturiser fully compensates — because the hydration deficit is happening from the inside out.
Quick Answer — What Is the Natural Moisturizing Factor?
Most people think of skin hydration as something that happens to the skin from the outside — applied through serums and creams. The reality is more interesting. Your skin produces its own moisturising system called the Natural Moisturizing Factor, or NMF — a complex of amino acids, sodium PCA, sodium lactate, betaine, and organic acids naturally present within the cells of your outermost skin layer. These compounds are highly water-attracting. Together they keep the stratum corneum supple, flexible, and capable of performing its barrier function.
NMF is not a product ingredient. It is a biological system. And like most biological systems, it can be depleted — by washing, ageing, UV exposure, and harsh skincare — faster than the skin can replenish it.
If your skin feels perpetually tight, dry, or dull despite consistent moisturiser use, NMF depletion is considered one of the contributing factors worth addressing.At a Glance
| What it is | The skin's own built-in humectant system — a complex of moisture-binding compounds within stratum corneum cells |
| Location | Inside corneocytes — the cells of the stratum corneum (outermost skin layer) |
| Key components | Amino acids (~40%), sodium PCA (~12%), sodium lactate (~12%), PCA, betaine, urea, urocanic acid, inorganic salts |
| Primary function | Maintains stratum corneum water content; supports skin flexibility and normal desquamation |
| Depleted by | Washing, harsh cleansers, UV exposure, low humidity, ageing, alcohol-based products |
| Replenished by | Topical NMF-mimicking ingredients: sodium PCA, amino acids, sodium lactate, betaine, PCA |
| Relationship to HA | Complementary — NMF hydrates from within the stratum corneum; HA hydrates the skin surface |
| Evidence base | Strong — NMF is well-characterised in dermatological literature since the 1950s |
The Bottom Line
- NMF is not a cosmetic concept — it is a biological reality. It has been characterised in dermatological science since the 1950s and is one of the most well-understood aspects of stratum corneum physiology.
- It is composed primarily of amino acids (~40%), sodium PCA (~12%), sodium lactate (~12%), PCA, betaine, urea, and urocanic acid — each of which is a potent hygroscopic compound that attracts and retains moisture within skin cells.
- NMF is water-soluble and is lost during every wash. A single cleanse with a harsh surfactant can deplete the NMF significantly — and skin needs time to replenish it through the natural filaggrin breakdown process.
- As skin ages, NMF production declines. UV exposure accelerates this decline by damaging filaggrin — the precursor protein from which most NMF components are derived.
- Topically applied NMF components — sodium PCA, amino acids, sodium lactate, betaine — are well-evidenced humectants that supplement depleted NMF at the stratum corneum level, where they are most directly relevant to surface hydration support.
- Surface moisturisers (occlusives, emollients) address TEWL from outside. NMF addresses hydration from inside the corneocyte. Both are needed — but most routines only address one.
In This Article
- What is the Natural Moisturizing Factor?
- The NMF components — what skin makes and why
- How NMF keeps skin hydrated — the mechanism
- The filaggrin connection — where NMF comes from
- What depletes NMF — and how quickly
- NMF and skin ageing — the overlooked factor
- NMF vs hyaluronic acid — different hydration systems
- Can you replenish NMF topically? What the evidence says
- How to support NMF — a practical protocol
- Who needs NMF support most?
- Frequently asked questions
- Conclusion
Walk into any pharmacy and you will find dozens of moisturisers. Most of them work by sitting on the surface of the skin — forming a film that slows water evaporation. They are useful. But they address only one part of how skin stays hydrated.
The other part — the part most skincare conversations almost entirely ignore — is happening inside the cells of your outermost skin layer. It is called the Natural Moisturizing Factor, or NMF. Understanding what NMF is in skincare, how it drives NMF skin hydration, and how to restore NMF when it depletes changes how you approach every step of your routine. It has been known to dermatologists for over seventy years. And yet it rarely appears in consumer skincare education — except in the INCI lists of well-formulated serums, where its components quietly do their work.
The natural moisturizing factor benefits for skin are not about a single ingredient. They are about a biological system your skin already runs — one that requires protection, not replacement.
01 — The Concept
What Is the Natural Moisturizing Factor?
The term "Natural Moisturizing Factor" was introduced in dermatological literature in the 1950s to describe the collection of water-soluble, hygroscopic substances found within the corneocytes — the flattened, protein-rich cells that make up the stratum corneum, the skin's outermost layer.
NMF is not a single molecule. It is a complex mixture — a biological humectant system — whose components are derived primarily from the breakdown of a structural protein called filaggrin. As corneocytes mature and move toward the skin surface, filaggrin is progressively broken down into the individual amino acids and related compounds that collectively constitute NMF.
These compounds are highly hygroscopic — meaning they have a strong affinity for water. Concentrated within the corneocytes, they attract and hold water from the environment and from the deeper layers of the epidermis, maintaining the moisture content of the stratum corneum from the inside. This is the defining function of NMF: it hydrates the skin cell itself, not just the surface around it.
02 — The Components
The NMF Components — What Skin Makes and Why
NMF is composed of approximately a dozen distinct compound classes, each contributing to the overall hygroscopic capacity of the stratum corneum. The relative proportions have been extensively characterised in the dermatological literature.
| Component | Approx. % of NMF | Role |
|---|---|---|
|
Free amino acids Serine, alanine, glycine, proline, glutamic acid, threonine, arginine, lysine and others |
~40% | The largest fraction of NMF by weight. Each amino acid is a highly effective humectant that attracts and holds water within the corneocyte. Serine and alanine are among the most abundant. |
|
Sodium PCA (sodium pyrrolidone carboxylic acid) |
~12% | One of the most potent humectants in the skin's own arsenal — associated with binding large amounts of moisture. Derived from glutamic acid via the same filaggrin breakdown process. |
| Sodium lactate | ~12% | A salt of lactic acid with significant hygroscopic capacity. Also contributes to maintaining the slightly acidic pH of the acid mantle — supporting the skin's microbiome and barrier enzyme activity. |
|
PCA (pyrrolidone carboxylic acid) |
~2% | The free acid form of sodium PCA. Contributes to the overall humectant capacity of NMF and to stratum corneum pH regulation. |
| Betaine | Trace–moderate | An osmolyte — a compound that helps cells regulate water balance under environmental stress. Protects corneocytes from osmotic pressure changes caused by fluctuating humidity. |
| Urea | ~7% | A keratolytic humectant that also supports normal desquamation. Helps maintain the flexibility of the stratum corneum. Depleted significantly in dry skin conditions. |
| Urocanic acid | ~2% | A UV-absorbing compound derived from histidine breakdown. Contributes to both hydration and the skin's natural photoprotective capacity within the stratum corneum. |
| Inorganic salts, sugars, organic acids | Remainder | Contribute to ionic balance, osmotic regulation, and the overall hygroscopic environment within the corneocyte. |
03 — The Mechanism
How NMF Keeps Skin Hydrated — The Mechanism
The mechanism by which NMF maintains stratum corneum hydration is fundamentally different from how topical moisturisers work — and understanding this difference explains why NMF depletion produces a type of dryness that moisturisers alone cannot resolve.
The stratum corneum is a two-phase system: the protein-rich corneocytes (the cells) and the lipid-rich intercellular matrix (the space between cells). Hydration of this structure depends on both phases performing their functions correctly.
NMF operates within the corneocytes themselves. The hygroscopic NMF compounds attract water from the environment — even at relatively low ambient humidity — and hold it within the cell. This internal water reservoir keeps each corneocyte flexible, maintains the mechanical properties of the stratum corneum as a whole, and supports the enzymatic activity that drives normal desquamation (skin shedding).
When NMF is depleted, the corneocytes lose this internal hydration. They become rigid and fragile. The stratum corneum loses its flexibility — leading to the characteristic tightness, flaking, and roughness of dehydrated skin. Applying an occlusive moisturiser to the surface can slow further water loss, but it cannot restore the internal hydration of the corneocytes. Only replenishment of the NMF components themselves — either through biological synthesis or topical supplementation — achieves this.
Two hydration systems, two locations, one skin
Think of skin hydration as having two distinct addresses. Inside the corneocyte: NMF compounds hold water within the cell, maintaining corneocyte flexibility and enzymatic function. Outside the corneocyte: the intercellular lipid matrix and topical humectants (including hyaluronic acid) manage water at the cell surface and at the skin surface above. A well-hydrated stratum corneum requires both addresses to be functioning — which is why NMF-mimicking ingredients and surface humectants are complementary, not interchangeable.
04 — The Source
The Filaggrin Connection — Where NMF Actually Comes From
Most of the NMF within the stratum corneum — particularly the amino acid fraction and sodium PCA — is derived from the breakdown of a single structural protein: filaggrin (filament aggregating protein).
Filaggrin is produced during the final stages of keratinocyte differentiation as cells move from the granular layer of the epidermis toward the stratum corneum. As the cell flattens into a corneocyte, filaggrin aggregates the keratin filaments that give the corneocyte its structure. Once this structural function is complete, filaggrin itself is progressively broken down — through a cascade of enzymatic reactions — into its constituent amino acids and their metabolites. These become the NMF.
This process means that NMF production is entirely dependent on filaggrin availability. And filaggrin availability is influenced by genetics, age, UV exposure, and skin condition.
05 — Depletion
What Depletes NMF — And How Quickly
Because NMF is water-soluble and located within the superficial cells of the stratum corneum, it is surprisingly vulnerable. Understanding its depletion pathways is essential for understanding why certain common skincare habits — even well-intentioned ones — can undermine skin hydration.
| Depletion Factor | Mechanism | Speed of Effect |
|---|---|---|
| Washing and cleansing | NMF compounds are water-soluble. Each wash extracts a proportion of surface NMF — even with water alone. Surfactants increase the rate of extraction significantly. | Immediate — measurable after a single wash |
| Harsh surfactants (SLS, SLES, alkaline soaps) | Disrupt the lipid barrier, increasing NMF accessibility to water; alkaline pH impairs the barrier enzyme activity needed to maintain NMF | Rapid — compounds effect of washing |
| Low-humidity environments | Hygroscopic NMF compounds are equilibrium-driven — in very low humidity, they may release moisture to the environment rather than retaining it | Hours — worse in air conditioning and heated spaces |
| UV exposure | UV radiation damages filaggrin directly and impairs the enzymatic cascade that produces NMF components; urocanic acid (an NMF component) is photolysed by UV | Cumulative — accelerates with repeated unprotected exposure |
| Ageing | Filaggrin expression declines with age; the enzymatic processes that generate NMF become less efficient; NMF content measurably lower in aged skin | Gradual — progressive from mid-twenties onward |
| High-concentration alcohol in products | Disrupts lipid barrier integrity; increases permeability to NMF loss; dries the stratum corneum directly | Rapid — after each application |
| Over-exfoliation | Removes superficial corneocytes faster than they are replaced; reduces the total NMF-containing cell mass in the stratum corneum | Cumulative with frequency of exfoliation |
06 — NMF and Ageing
NMF and Skin Ageing — The Overlooked Factor
Most conversations about skin ageing focus on collagen, elastin, and hyaluronic acid — the structural and hydrating components of the dermis. The stratum corneum's own hydration system is rarely discussed in the same breath. Yet the age-related decline in NMF is one of the most consistently documented changes in skin physiology with ageing.
Research has shown that NMF content in the stratum corneum declines measurably with chronological age — particularly the amino acid and sodium PCA fractions. This decline is associated with the characteristic features of aged skin: increased surface dryness and roughness, impaired barrier function, slowed desquamation, and a visibly duller surface appearance.
UV exposure accelerates this process. Filaggrin is among the proteins damaged by both UVA and UVB radiation. Chronically sun-exposed skin shows significantly lower NMF content than age-matched unexposed skin — which is one of the dermatological mechanisms underlying the faster visible ageing observed in sun-damaged skin.
The dullness–NMF connection
One of the least-discussed but most consistent consequences of NMF depletion is a loss of surface radiance. Properly hydrated corneocytes are translucent and light-reflective — they create the appearance of brightness and even tone. Dehydrated corneocytes scatter light irregularly, producing the flat, dull appearance associated with chronically dry and dehydrated skin. Supporting NMF replenishment — through a combination of NMF-mimicking topicals, barrier support, and SPF — addresses this at its source rather than temporarily masking it with surface luminising ingredients.
07 — NMF vs Hyaluronic Acid
NMF vs Hyaluronic Acid — Different Hydration Systems
Hyaluronic acid — or more precisely, sodium hyaluronate in its cosmetic salt form — is often positioned as the gold standard of skin hydration. It is a highly effective humectant, well-evidenced, and widely used. But it is not the same as NMF, and understanding the difference clarifies why using both together is more effective than either alone.
| Factor | Natural Moisturizing Factor | Sodium Hyaluronate (HA) |
|---|---|---|
| Origin | Produced biologically within the skin from filaggrin breakdown | Applied topically; produced by biofermentation |
| Location | Inside corneocytes — within stratum corneum cells | Skin surface and upper epidermis (MW-dependent) |
| Mechanism | Intracellular hygroscopic system — hydrates from within the cell | Surface and epidermal humectant — attracts water to the skin surface |
| Molecular size | Small water-soluble molecules — amino acids, PCA, lactate | Large polysaccharide — MW determines depth of action |
| Lost by washing? | Yes — highly water-soluble; lost with each cleanse | Yes — washed off with each cleanse; must be reapplied |
| Best used together? | Yes — they hydrate at different depths and through different mechanisms. NMF supports intracellular hydration; HA supports surface and epidermal hydration. Together they provide comprehensive multi-depth hydration coverage. | |
08 — Topical Evidence
Can You Replenish NMF Topically? What the Evidence Says
Yes — and this is one of the more elegantly simple concepts in cosmetic science. The individual components of NMF are well-characterised, water-soluble, skin-compatible, and available as cosmetic ingredients. Applied topically, they can supplement depleted NMF at precisely the skin layer where NMF operates — the stratum corneum.
Sodium PCA — the most studied NMF humectant
Sodium PCA is the NMF component with the most extensive topical evidence base. Studies have consistently associated topical sodium PCA application with improved stratum corneum hydration, reduced TEWL, and improved skin feel in both normal and dry skin models. It is well tolerated, non-sensitising, and effective at low concentrations. Its presence in a formulation alongside other NMF components represents a biomimetic approach to stratum corneum hydration support.
Amino acid complexes — the largest NMF fraction
Free amino acids — including serine, glycine, alanine, proline, threonine, arginine, glutamic acid, and lysine — constitute approximately 40% of NMF by weight. Individually, each is a modest humectant. Together, in a blend that mirrors the natural NMF amino acid profile, they have been associated with meaningful improvements in stratum corneum hydration in research settings. The hygroscopic action of the amino acid complex is additive — the blend outperforms any single amino acid applied at equivalent concentration.
Sodium lactate
Sodium lactate is both a humectant and a mild exfoliant — it supports normal desquamation while simultaneously improving moisture retention. At the concentrations typical of NMF-supportive formulations, its contribution to hydration is significant. It also supports acid mantle pH, complementing the microbiome-protective properties of a well-formulated skincare routine.
Betaine — the osmolyte
Betaine functions as a cellular osmolyte — protecting corneocytes from osmotic stress caused by changes in environmental humidity. Its inclusion in a multi-component NMF formulation addresses one of the mechanisms by which the stratum corneum loses flexibility under low-humidity conditions.
09 — Protocol
How to Support NMF — A Practical Protocol
Supporting NMF requires both protecting what the skin produces naturally and replenishing what is lost through daily life. The two strategies are distinct and equally important.
NMF-Supportive Skincare Protocol
Every wash removes NMF. The goal is not to stop cleansing but to minimise unnecessary NMF loss by using the gentlest effective cleanser — SLS-free, pH 4.5–6.0 — and avoiding over-washing. Morning rinse with water alone is sufficient for most skin types and dramatically reduces daily NMF extraction.
The window immediately after cleansing — when the stratum corneum is slightly swollen with water — is the optimal moment to apply NMF-supportive ingredients. Sodium PCA, amino acid complexes, sodium lactate, and betaine applied at this point may supplement depleted NMF while the skin surface is most receptive. Apply before any occlusive layer.
After NMF-mimicking ingredients, apply a surface humectant — sodium hyaluronate — to address the complementary surface-level hydration that NMF alone does not cover. The two systems together provide hydration at both the intracellular and surface levels of the stratum corneum.
Apply ceramides, squalane, or an emollient moisturiser over the humectant layers to reduce TEWL — slowing the evaporation of the moisture that the NMF and surface humectants have attracted. Without this step, particularly in low-humidity environments, both NMF and surface humectants may not retain the moisture they draw in.
UV radiation directly damages filaggrin — the protein from which NMF is derived. Every day of unprotected UV exposure contributes to the structural impairment of the skin's NMF-generating system. SPF is not simply a cancer prevention measure in this context — it is a direct investment in the skin's ability to produce and maintain its own hydration system over time.
Over-exfoliation removes corneocytes — the cells that contain NMF — faster than the skin can replace them. If skin feels persistently tight or reactive, reducing exfoliation to once per week and focusing on barrier and NMF support for 4–6 weeks before reintroducing acids is the most physiologically coherent approach.
10 — Suitability
Who Needs NMF Support Most?
While NMF depletion affects everyone to some degree — because washing alone is sufficient to cause measurable loss — certain individuals and circumstances produce significantly greater NMF deficit:
| Profile | Why NMF is particularly relevant |
|---|---|
| Dry and chronically dehydrated skin | Often reflects persistent NMF depletion rather than simply a lack of surface moisturiser. Tightness, flaking, and discomfort that persist despite moisturiser use are characteristic NMF depletion signs. |
| Mature skin (40s and beyond) | Filaggrin expression and the NMF-generating enzyme cascade are measurably less active with age. NMF replenishment becomes progressively more important as biological production declines. |
| Eczema and atopic dermatitis-prone skin | Filaggrin loss-of-function mutations impair NMF production structurally. NMF-supportive topicals are a central component of managing the hydration deficit in atopic skin, alongside barrier lipid repair. |
| Frequent or over-cleansers | Multiple daily washes, foam cleansers, micellar waters — each cleansing step removes a portion of NMF. People who cleanse more than twice daily are at particular risk of cumulative depletion. |
| Retinoid users | Retinoids accelerate cell turnover, which can temporarily outpace the NMF-generating process. Supporting NMF topically during retinoid use helps maintain stratum corneum hydration during the adaptation period. |
| Post-procedure skin | After chemical peels, microneedling, or laser procedures, the stratum corneum is temporarily thinned and NMF content is reduced. NMF-supportive ingredients support the hydration environment during barrier recovery. |
| Low-humidity climates and environments | Air conditioning, central heating, high altitude, and arid climates all accelerate the equilibrium-driven loss of moisture from NMF compounds. NMF replenishment is more important in these environments than in temperate, humid conditions. |
11 — FAQ
Frequently Asked Questions
What is the Natural Moisturizing Factor?
The Natural Moisturizing Factor (NMF) is a complex of water-soluble, hygroscopic compounds found naturally within the corneocytes of the stratum corneum — the skin's outermost layer. Composed primarily of amino acids, sodium PCA, sodium lactate, PCA, betaine, and urea, it is the skin's own built-in humectant system, responsible for maintaining the moisture content of the skin surface from within the cell.
What are the components of the Natural Moisturizing Factor?
NMF is composed of approximately: free amino acids including serine, alanine, glycine, proline, threonine, arginine, glutamic acid, and lysine (~40%); sodium PCA (~12%); sodium lactate (~12%); urea (~7%); PCA (~2%); urocanic acid (~2%); and various inorganic salts, sugars, and organic acids making up the remainder. Most components are derived from the enzymatic breakdown of the structural protein filaggrin within maturing corneocytes.
What depletes the Natural Moisturizing Factor?
NMF is depleted primarily by washing — because its components are water-soluble and extracted with each cleanse. Harsh surfactants, alkaline soaps, low humidity, UV exposure, ageing, high-concentration alcohol in products, and over-exfoliation all contribute to depletion. The speed of depletion (minutes to hours) is significantly faster than natural replenishment (days), creating a gap that topical NMF supplementation can address.
Can topical skincare replenish NMF?
Yes — topically applied NMF components including sodium PCA, free amino acids, sodium lactate, betaine, and PCA have been shown in research to supplement depleted NMF at the stratum corneum level. These ingredients are water-soluble, well-tolerated, and well-suited to stratum corneum hydration support — they operate at exactly the skin layer where NMF functions. Multi-component systems that approximate the natural NMF composition are more effective than single-humectant approaches for this purpose.
Is NMF the same as hyaluronic acid?
No — they are different systems. NMF is a complex of small water-soluble molecules found inside the corneocytes of the stratum corneum. Hyaluronic acid (sodium hyaluronate) is a large glycosaminoglycan found primarily in the dermis and applied topically to the skin surface and upper epidermis. NMF hydrates from within the skin cell; HA hydrates at the surface and epidermal level. Both are important — they address different depths of skin hydration and are most effective when used together.
Is NMF relevant for oily skin?
Yes — oil production (sebum) and skin hydration (water content) are independent systems. Oily skin can be simultaneously dehydrated — and often is, particularly if harsh cleansers or alcohol-based products have been used to manage oiliness. NMF-supportive ingredients are lightweight, water-soluble, and non-comedogenic, making them appropriate for oily and combination skin types as well as dry skin.
What does sodium PCA do in skincare?
Sodium PCA (sodium pyrrolidone carboxylic acid) is one of the most abundant and potent components of the Natural Moisturizing Factor, comprising approximately 12% of NMF by weight. As a topical ingredient, it is associated with binding large amounts of moisture within the stratum corneum, supporting skin hydration and suppleness. It is well-tolerated, non-irritating, and effective at low concentrations — making it one of the most physiologically coherent humectant ingredients in cosmetic formulation.
12 — Conclusion
Your Skin Already Knows How to Stay Hydrated. It Just Needs You to Stop Undermining It — and Start Supporting It.
The Natural Moisturizing Factor is not a new concept. It is not a marketing term. It is one of the most well-established mechanisms in stratum corneum physiology — documented in the dermatological literature for over seventy years — and it is the reason that two people can use the same moisturiser and have dramatically different results.
If the skin's own NMF system is intact and supported, topical skincare works with it. If NMF is chronically depleted — by washing habits, harsh products, UV exposure, or ageing — topical skincare is working against a physiological deficit that surface-only approaches cannot resolve.
The practical implications are clear: protect NMF by cleansing gently and less aggressively. Replenish NMF with multi-component amino acid and sodium PCA-based formulations applied immediately after cleansing. Support the barrier with occlusives. Protect filaggrin with daily SPF. Layer with sodium hyaluronate for complementary surface hydration.
This is not a complex routine. It is a physiologically coherent one — built on what the skin's own hydration biology actually requires.
NMF-Mimicking Complex in CellMorph™ 500
CellMorph™ 500 is formulated with a comprehensive amino acid and NMF-component complex — including sodium PCA, betaine, sodium lactate, and free amino acids — alongside patent-pending submicronised spicule technology that supports enhanced ingredient interaction with upper skin layers. NMF replenishment as part of an advanced active serum system.
Explore CellMorph™ 500 — engineered to support NMF at the source →CellMorph™ 500
Combines a multi-component NMF amino acid and sodium PCA complex with submicronised spicule technology, apple stem cells, hydrolysed elastin, nanopeptide-1, tranexamic acid, and dragon blood extract. Advanced active serum for comprehensive skin renewal support.
Shop CellMorph™ 500 →Aquablur™
Formulated around a multi-molecular weight hyaluronic acid system — complementing NMF's intracellular hydration with layered surface and epidermal humectant coverage. Fragrance-free, skin-compatible pH.
Shop Aquablur™ →SkinReset™ PDRN Serum
PDRN-based barrier recovery serum — supports the structural skin environment in which NMF functions. Fragrance-free, formulated for reactive and compromised skin types. Barrier restoration as the foundation of NMF support.
Shop SkinReset™ →Why persistent dryness often does not respond to moisturiser alone
The most commonly observed pattern with significant NMF depletion is persistent skin dryness that does not resolve with standard moisturiser use. People often interpret this as a need for a richer or heavier moisturiser — and apply increasingly occlusive products without improvement. The issue is that the hydration deficit is inside the corneocyte, not at the surface. Occlusives can slow water loss but cannot rehydrate a corneocyte that lacks the internal hygroscopic compounds to hold water in the first place. Addressing NMF directly — with the right topical ingredients applied at the right time — is the most appropriate response to this pattern.
Scientific References
- Rawlings, A.V., & Harding, C.R. (2004). Moisturization and skin barrier function. Dermatologic Therapy, 17(Suppl 1), 43–48.
- Harding, C.R. (2004). The stratum corneum: structure and function in health and disease. Dermatologic Therapy, 17(Suppl 1), 6–15.
- Elias, P.M. (2005). Stratum corneum defensive functions: an integrated view. Journal of Investigative Dermatology, 125(2), 183–200.
- Proksch, E., Brandner, J.M., & Jensen, J.M. (2008). The skin: an indispensable barrier. Experimental Dermatology, 17(12), 1063–1072.
- Segger, D., & Schönlau, F. (2004). Supplementation with Evelle® improves skin smoothness and elasticity in a double-blind, placebo-controlled study with 62 women. Journal of Dermatological Treatment, 15(4), 222–226.
- Fluhr, J.W., Darlenski, R., & Surber, C. (2008). Glycerol and the skin: holistic approach to its origin and functions. British Journal of Dermatology, 159(1), 23–34.
- Smith, F.J.D., et al. (2006). Loss-of-function mutations in the gene encoding filaggrin cause ichthyosis vulgaris. Nature Genetics, 38(3), 337–342.
- Koyama, J., et al. (2009). Sodium PCA and the skin — a study of NMF component replenishment following topical application. Journal of Cosmetic Science, 60(1), 1–8.
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