Lipid Barrier
Definition
The lipid barrier (also called the lipid matrix or lipid bilayer) is the intercellular 'mortar' between the corneocytes (dead skin cells) in the stratum corneum. It is composed of approximately 50% ceramides, 25% cholesterol, and 15% free fatty acids, arranged in organized lipid layers. This structure is essential for the skin's barrier function — it prevents excessive transepidermal water loss (TEWL), protects against the penetration of irritants, allergens, and microorganisms, and maintains skin hydration and flexibility. When the lipid barrier is disrupted — through harsh cleansing, over-exfoliation, environmental damage, or skin conditions like eczema — the skin becomes dry, irritated, and vulnerable. Repairing the lipid barrier involves using products that contain physiological lipids (ceramides, cholesterol, and fatty acids) in ratios similar to those found naturally in healthy skin.
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