Intercellular Lipids

Intercellular lipids are the fatty molecules that fill the spaces between skin cells in the outermost layer, acting as the mortar that binds the barrier together. They are essential to the skin's ability to hold water and keep irritants out.

In the stratum corneum, flattened dead cells are surrounded by an organised lipid matrix arranged in layered sheets. This matrix is made up of roughly three families of lipids working in balance: ceramides, cholesterol and free fatty acids. Together they form a continuous, water-resistant seal that regulates how much moisture escapes from the skin and blocks the entry of allergens and microbes. The characteristic brick-and-mortar model describes cells as the bricks and these lipids as the mortar filling the gaps.

When intercellular lipids are depleted, the barrier becomes leaky, allowing water to evaporate more quickly and letting irritants penetrate. This shows up as dryness, tightness, sensitivity and rough texture. Depletion can be driven by harsh cleansers, over-exfoliation, low humidity, ageing or frequent hot water. Restoring lipids generally involves moisturisers that supply the same components the skin uses, particularly ceramides alongside cholesterol and fatty acids, ideally in complementary proportions.

• Products combining ceramides, cholesterol and fatty acids aim to replenish the natural matrix rather than merely coat the surface.
• Gentle, non-stripping cleansing helps preserve existing lipids.

Supporting the lipid matrix is a foundation of barrier care, and it underpins how well other actives are tolerated.