What Are Ceramides?
Ceramides are a family of waxy lipid molecules that make up approximately 50% of the skin's stratum corneum lipid matrix. They are sphingolipids composed of a sphingosine backbone linked to a fatty acid chain, and they are the primary structural component of the "mortar" that holds corneocyte "bricks" together in the skin barrier. Without adequate ceramide levels, the barrier becomes permeable — allowing water loss and pathogen entry.
Types and Functions
There are at least 12 distinct ceramide subclasses (Cer[EOS], Cer[NS], Cer[NP] among the most studied). Each has slightly different chain lengths and positions but collectively they work to: create an impermeable lipid lamellae, prevent transepidermal water loss (TEWL), maintain skin hydration, and resist environmental insult.
Why Ceramides Decline
Ceramide synthesis naturally decreases with age — mature skin has measurably lower ceramide concentrations than younger skin, correlating with increased dryness and fine lines. Conditions like eczema (atopic dermatitis) are characterised by ceramide deficiency, particularly Cer[NP]. External factors — over-washing, harsh surfactants, low humidity — further strip existing ceramides.
Topical Replenishment
Topical ceramide formulations can partially restore barrier function. Best results come from products containing a physiological ratio of ceramides, cholesterol, and fatty acids (roughly 1:1:1 to 3:1:1 ratio), mimicking the natural lamellar structure. Apply after cleansing while skin is still slightly damp for optimal integration.
Evidence base: Ceramide-dominant moisturisers are classified as first-line therapy for atopic dermatitis in paediatric and adult dermatology guidelines.
See Barrier Repair & Ceramides and Lipid Barrier.