What ceramides do — and why they appear in almost every moisturiser.

Ceramides are lipids — fats — that occur naturally in the skin. They make up approximately 50% of the lipid content of the stratum corneum, the outermost layer of the epidermis. Together with fatty acids and cholesterol, they form the "mortar" in the skin's brick-and-mortar structure: the lipid matrix that holds the barrier together.

Understanding ceramides begins with the barrier. The barrier's primary functions are to prevent water from leaving the skin — limiting transepidermal water loss — and to prevent external irritants, allergens, and pathogens from entering. Ceramides are central to both.

What ceramides are

There are at least 12 distinct ceramide subclasses, each with slightly different molecular structures. They are found in every layer of the epidermis, with the highest concentrations in the stratum corneum. The skin biosynthesises ceramides and releases them into the extracellular space, where they form tightly packed lipid layers that constitute the barrier's matrix.

Ceramide production declines with age, cold weather, and overuse of disrupting cleansers or active ingredients. When ceramide levels fall, the lipid matrix becomes less dense, more permeable, and less effective at retaining moisture.

What they do in skincare

Topical ceramides reinforce the barrier. Applied in a moisturiser, ceramide molecules integrate into the existing lipid matrix, supplementing what the skin's own production cannot maintain. This reduces transepidermal water loss — measurably, in well-designed trials.

They are among the most evidence-backed moisturising ingredients. Ceramide-containing formulations have been studied extensively in the context of eczema, psoriasis, and general dry skin. The evidence for their role in barrier function and moisture retention is strong and consistent.

They are not actives. Ceramides do not resurface skin, reduce pigmentation, or regulate oil. They are structural — they perform the barrier function. They are not glamorous. They are the foundation.

Ceramides and niacinamide

Niacinamide increases ceramide synthesis from within the skin — it stimulates production of the same lipids that topical ceramides supply from outside. The combination is logical: one ingredient reinforcing the barrier from the outside, another stimulating the skin's own production from within.

The Lux & Glo moisturiser does not list ceramides directly — it uses squalane, shea butter, and avocado oil, which reinforce the barrier lipid matrix through their own mechanisms. The niacinamide serum addresses ceramide synthesis. The approach is the same in both directions: support the barrier, not just supplement it.

How to read ceramide claims on a label

Ceramides appear on ingredient lists under several names: Ceramide AP, Ceramide EOP, Ceramide NP, Ceramide NS — and most commonly as "ceramide" followed by a number (Ceramide 1, 3, 6-II). Multiple ceramide types in a single formulation more closely mirrors the skin's own composition. "Ceramide complex" usually indicates a blend.

Ceramides are stable in formulation. They do not require special activation, delivery mechanisms, or adjacent ingredients to function. A well-formulated product in opaque packaging is sufficient. The complexity should be in the research, not the claims.