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Skincare Guide - Skin Protection Function

Skin protection function – structure, disruption & maintenance of the skin barrier

What is meant by the skin protection function?

The skin 's protective function describes its ability to protect the body from external influences. It prevents the penetration of pollutants, microorganisms, and allergens while simultaneously regulating the skin's moisture balance. This complex protective barrier is located primarily in the outermost layer of skin—the epidermis —especially in the stratum corneum . <sup>1</sup>

Building the skin barrier

The barrier is often described as a "brick-and-mortar structure" : corneocytes form the bricks, while lipids (ceramides, cholesterol, and fatty acids) provide the mortar. This arrangement ensures stability and protects against transepidermal water loss (TEWL). 2

  • Corneocytes: dead cells that lie on top of each other like scales and provide mechanical protection.
  • Lipid matrix: prevents dehydration and keeps the skin supple.
  • Acid mantle: slightly acidic pH (~5.5) that keeps microorganisms in check. 3

Function of the skin barrier

The skin fulfills a dual function: it protects against external influences (external barrier) and regulates fluid balance (internal barrier). 4

  • Protection against pollutants and microbes: Lipids and antimicrobial peptides prevent the penetration of pathogens.
  • Water retention: natural moisturizing factors (NMF) such as urea, lactic acid and amino acids store water in the stratum corneum.
  • pH regulation: the acid mantle stabilizes enzymes involved in lipid formation.

What weakens the skin's protective function?

  • Excessive cleaning: aggressive surfactants and hot water dissolve lipids from the stratum corneum. 5
  • Climatic influences: Cold, dry air and UV radiation lead to moisture loss.
  • Stress and lack of sleep increase cortisol levels, which can inhibit lipid production.
  • Incorrect skincare products: Alcohol, synthetic fragrances, or high acid levels can cause irritation.
  • Skin diseases, such as atopic dermatitis or psoriasis, are associated with a disrupted skin barrier. 6

Signs of a disrupted skin barrier

  • Redness, tightness or burning
  • Dry, rough, or flaky skin
  • Hypersensitivity to care products
  • Impurities and inflammation due to a weakened barrier

How can the skin's protective function be strengthened?

  • Ceramides and fatty acids: replace missing lipids and stabilize the intercellular spaces. 7
  • Moisturizers: Hyaluronic acid, glycerin or urea bind water and plump up the skin.
  • Panthenol & Niacinamide: promote regeneration and soothe irritated skin. 8
  • Gentle cleansing: mild, pH-neutral products without alcohol or aggressive sulfates.
  • UV protection: Daily sun care protects lipids and cell structures from oxidation. 9

The relationship between microbiome and barrier

Recent studies show that the skin flora – the microbiome – plays an important role in protecting against pathogenic germs. A balanced microbial diversity supports the barrier function, while excessive disinfection or irritating skincare disrupts this balance. 10

Skin protection function and aging

With increasing age, the levels of ceramides and natural moisturizing factors decrease. This increases transepidermal water loss (TEWL), and the skin loses elasticity. Anti-aging formulations with lipid replenishers, antioxidants, and peptides can mitigate this process. 11

Conclusion

An intact skin barrier is key to healthy, resilient skin. Modern skincare products – like those from NATURFACTOR – combine barrier protection, lipid care, and antioxidant protection to strengthen the skin structure in the long term and maintain its natural balance.

Sources

  1. Wikipedia (DE): Skin. https://de.wikipedia.org/wiki/Haut
  2. DocCheck Flexikon: Stratum corneum. https://flexikon.doccheck.com/de/Stratum_corneum
  3. Wikipedia (DE): Acid mantle. https://de.wikipedia.org/wiki/S%C3%A4ureschutzmantel
  4. Springer Medicine: Skin barrier and skin protection. https://link.springer.com/article/10.1007/s00105-019-04533-2
  5. NetDoktor (DE): Proper skin cleansing. https://www.netdoktor.de/koerperpflege/hautpflege/
  6. Charité Berlin – Skin Diseases & Barrier Function. https://derma.charite.de/forschung/hautbarriere/
  7. Springer Medicine: Ceramides in skincare. https://link.springer.com/article/10.1007/s00105-020-04697-3
  8. Wikipedia (DE): Niacinamide. https://de.wikipedia.org/wiki/Nicotinamide
  9. German Cancer Aid: Sun Protection & Skin Cancer Prevention (PDF). https://www.krebshilfe.de/fileadmin/Downloads/PDFs/Praeventionsratgeber/407_0076.pdf
  10. Springer Medicine: Skin microbiome and barrier function. https://link.springer.com/article/10.1007/s00105-020-04750-1
  11. DocCheck Flexikon: Skin aging. https://flexikon.doccheck.com/de/Hautalterung
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